Category Archives: Physiology News

Articles pulled from our magazine, Physiology News.

Friends in high places: Researchers go global for answers at high altitude (Part 2)

By Alexandra Williams, @AlexM_Williams

This blog is the second and final part of a series that began here.

Experience

1 July 2018, Day 2 at altitude

The viscometer is being set up in the bloods room and is a key weapon in our arsenal for primary outcome measures in multiple studies. Due to voltage differences (compared to Canada) the unit needs to be connected to a step-down. We connect the viscometer, water bath and the step-down, and at first all seems to be functioning well. A few minutes later, an odd scent emerges. Ah, the step-down is smoking, not good! This unfortunately is not the first fire hazard we’ve encountered. In Nepal, one of our technicians had to rewire most of the outlets to ensure they wouldn’t catch flame. A few days ago, an outlet connected to a locally-made space heater went alight. We are constantly having to double- and triple-check that our equipment doesn’t melt due to poor electrical wiring, or mismatched voltage inputs/ outputs. At the same time, though, we more often find ourselves very thankful that we have electricity to power the large volume of studies being conducted in these remote locations.

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Views from the valleys: descent through Lobuche Pass, Nepal 2016 (top) and Ticlio Pass, Peru 2018 (bottom), both ~4800-5000 m altitude.

These expeditions provide comprehensive research experience and encourage growth amongst the team and its individuals. Things are not always sunshine, rainbows and unicorns, though the many logistical hurdles provide an opportunity for learning and developing our problem-solving abilities.

We often must think outside of the box and utilise our creative capacities to circumvent roadblocks, technical difficulties and unexpected challenges.

Aside from common technical conundrums, there are often cultural barriers that are both interesting and of course region-dependent. One obvious challenge is language – in Nepal, this was less obvious because many of the porters and Sherpa required some English for their work in tourism. Surprisingly to us, Peru has proved much more difficult, as virtually no one in Cerro de Pasco speaks a language other than Spanish. In fact, the local residents have an accent that is ‘poquito’ difficult for our translators to understand, so trying to explain protocols can be tricky. For example, measurements of total blood volume using the carbon monoxide rebreathe technique require the participant to complete a few steps: fully empty the lungs; attach to the spirometer mouthpiece; turn the valve; rapidly fill the lungs and hold for ten seconds; breathe normally for two minutes into the spirometer; then empty the lungs and turn the valve to close the system… all without breaking the glass spirometer (Fig. 2). Simple, right? Not so much. Despite our efforts to perform practice runs and explain the protocol several times over with physical demonstrations and translators, this is notably challenging.

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Members of the Global REACH team, in 2016 at the Ev-K2-CNR Laboratory (5050m) in Khumjung region, Nepal (top) and recently in 2018 at the Institutio de Investigaciones de la Altura (4350m) in Cerro de Pasco, Peru (bottom).

While these international expeditions allow us to become immersed in a different geographical and cultural environment, certain local traditions or values unbeknownst to us can provide unexpected barriers. In Nepal, the Sherpa were incredibly kind, and almost always smiling. They would seldom show negativity or utter complaints. One of our prime focuses on these expeditions is to examine blood markers of inflammation, blood gases and hematocrit concentration. In Nepal we collected serial arterial and venous blood samples at every stop during our ascent, but in Pheriche, one stop before the Pyramid, the Sherpa began to show concern, some requesting to skip the blood draws. We would find out the Sherpa perceived blood as their lifeforce, and that once lost, blood could not be replaced. They believed the loss of blood would weaken them and impair their state of being.

One translator mentioned the word ‘vampire’ and explained the concern that their blood might be sold. Luckily, with the help of our lead Sherpa and a few of the elders, we were able to convey that the bloods were solely used for research purposes and that we would never take more than necessary for study.

1 July 2018, day 2 at altitude; 16:05 h

I look over after completing one great blood volume test on the fourth Andean participant today (we’re getting more effective at translating) and the viscometer is now working, with a step-down that isn’t smoking! Turns out the previous step-down was pulled off the shelves of the Cerro lab. We’ve found one of our own from Canada and it has worked like a charm. With a bit of flexibility and a sprinkle of luck, these things often happen to work out.

Despite the aforementioned challenges, these expeditions provide overwhelmingly positive experiences, opportunities for personal growth and adventure. As researchers, we gain incredible organisational skills: much like a game of Tetris, we learn to schedule participants amongst multiple studies, ensuring a fine balance between efficiency and crossover i.e. that no measures conflict with other studies. Our communication skills grow as we continually coordinate between our local contacts, the P.I.s and the rest of the team. Even when things go completely off-plan, we learn to utilise flexibility and make the best of challenging situations. This field-based research teaches us quick thinking, adaptability (no pun intended) and resourcefulness. The challenges themselves provide strong learning experiences to be applied moving forward.

Perhaps the most obvious and enticing draw of these expeditions is the element of adventure. Not surprisingly, team leader Phil Ainslie’s initial involvement in altitude research was borne from his job as a mountain guide before attending university. ‘The first (trip) was when I was 22 or 23… I was running a trip in northwest India to some peaks at 6,000 m or 7,000 m. Damian (Bailey) was my instructor and he asked, ‘would you collect some blood samples’? And I said, ‘sure’. I spun samples down with a hand-crank centrifuge at 5,000 m on 25 people and took (saturation) measures, just me. And brought it all back. I’ve gone back (to altitude) every few years since.’ Following Phil’s lead, these expeditions allow us to explore incredible regions and share awe-inspiring experiences with our international collaborators. Visiting Everest Base Camp or climbing a (slightly dangerous) hill to look out at the Andes creates a bond of friendship and provides the foundation for long-lasting international collaborations that define Global REACH.

Team

9 July 2018; 21:53 h

Phil Ainslie (University of British Columbia), Mike Stembridge (Cardiff Metropolitan University), Craig Steinback (University of Alberta) and Jonathan Moore (Bangor University) and I are sat in the lobby of our hotel, chatting over a few Cusqueña beers. While discussing the 2016 Nepal Expedition, I explained how impressed I was that a group of 37 individuals had worked so well together, with no obvious dramas despite living in a harsh environment.

‘It’s similar to the New Zealand All Blacks values… basically the ‘no dickheads’ rule’, one of us said. We all laughed, then nodded in agreement. ‘Well, much like in mountaineering leadership, a mantra of the All Blacks rugby team is that they ‘sweep the sheds’, meaning that it doesn’t matter if you’re the star player – everyone on the team cleans the dressing room. If you’re a dickhead, if you’re not a team player, you’re not part of the All Blacks.

Phil has explicitly provided permission to include this conversation in the article, because while blunt, this type of value characterises the core of our collaborations and ensures the success of the expeditions. When everyone works together, dismisses ego and shares positive energy, the team thrives. Sixteen-hour testing days become relatively easy when you’re having fun.

Our team is at the heart of our success. We embrace collaborators with infectious personalities that border on the sides of eclectic and hyperactive: those with a genuine passion for research and zest for life. Team members remind each other to look beyond the academic pressures of funding and publication for the sake of career progression and light a fire and excitement for discovery.

Our peers drive us to new heights, literally and figuratively, in our academic prowess. We find less pride in our individual successes than in those of our teammates.

Our leaders – Phil Ainslie, Mike Stembridge and the late Christopher Willie – continue to inspire us. Their energy brings the continents together to create impressively cohesive and brilliant multidisciplinary collaborations. Their teams will continue to go global and reach for answers to important health-related questions at Earth’s highest altitudes.

(You can read the full article in its original version in Physiology News magazine.)

Friends in high places: Researchers go global for answers at high altitude (Part 1)

By Alexandra Williams, @AlexM_Williams

Global Research Expedition on Altitude Related Chronic Health (or Global REACH) is an international collaboration of academics and physicians from 14 institutions across Canada, the UK, the US, Peru and Nepal. While the “Global REACH” title is relatively new, its leaders have conducted a multitude of expeditions over the last decade to Nepal’s Himalaya, California’s White Mountains and now Peru’s Andes. With a collective interest in heart, lung and vascular health and altitude medicine, Global REACH’s collaborations ultimately aim to understand how the human body adapts, or maladapts, chronically to the low oxygen environments of earth’s highest altitudes.

I am writing this from 4,300 m, at the Laboratorio de Cerro de Pasco and Institutio de Investigaciones de la Altura in Peru. Our team of over 40 researchers, trainees, principal investigators and physicians are currently conducting approximately 20 studies examining heart, lung and brain physiology in lowlanders (us) and Andean highlanders with and without chronic mountain sickness.

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Example of a centrifuged blood sample from an Andean participant with chronic mountain sickness. A normal, healthy lowlander’s hematocrit (i.e. fraction of red cells in the blood) is ~40%; several Andean participants including this one had hematocrit values of 75-80%.

This series of blogs, however, does not intend to outline our experiments or specific scientific findings (which was described in a recent issue of Physiology News). Instead, you will get a raw, behind-the-scenes look at what transpires on these expeditions: the challenges we face, the experiences we gain, and most importantly the team values that drive the success of these international collaborations.

30 June 2018: Day 1 at altitude

Yesterday, the last of three groups of the Global REACH team drove from sea level in Lima up to 4,300 m in Cerro de Pasco, Peru. Amongst the team, some individuals are feeling “okay” (say, a rating of 7/10), while others have been in bed with splitting headaches for more than 24 hours. We would later discover that one, in fact, had a bout of pneumonia. Nevertheless, one thing remains constant across the team – the excitement. It is palpable. Seven lab bays are set up, participants are being scheduled in, the equipment is (mostly) accounted for and working. Data collection has already begun today, and our first Andean participants are coming in tomorrow morning. This is what we came for, and we’re ready for the fun to begin.

For those who haven’t experienced the thin air of Earth’s highest mountain ranges, a 7-hour jump from sea level to over 4,300 m altitude is significant, one which often leaves individuals feeling much worse than “not great.” Yet, with advanced knowledge of the side effects of altitude and hypoxic exposure, Global REACH members have joined forces to answer a plethora of physiological questions. For many, this will mark more than four expeditions to high altitude, a select few even in the double digits. In the first few days, most – including our team leaders – will have headaches, nausea, sleep disturbances and apnoeas. The inter-individual variability of these symptoms is quite high, as a select few may feel fine, most will feel some magnitude and combination of the list, and others will be periodically out of commission.

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Performing a carbon monoxide rebeathe test to measure red cell volume and total blood volume with an Andean participant in Cerro de Pasco. This method is technically challenging, and is made more difficult with a significant language barrier.

So, why do we do it? Why do we involve ourselves with the potential suffering at altitude and any additional risks (i.e. transport, illness) kindred to these trips? From my experience, three fundamental elements outweigh the risks and define the success of expeditions and collaborations like Global REACH: the science, the experience, and the team.

Science

1 July 2018: Day 2 at altitude

“MAS FUERTE, MAS FUERTE, yeah Johnny!” Johnny, our first Andean participant is laying on the bed of testing Bay 1, currently practising a handgrip protocol for a vascular study. Johnny already has a venous catheter placed in his forearm and will be shuttled through a screening circuit: ultrasound imaging (cardiac, ocular and vascular), a maximal exercise test and assessment of total blood volume. Our Spanish skills are currently dismal, but we’re managing to compliment the amazing work of our translators to collect a large cardiovascular dataset on approximately 50 Andean participants.

3 July 2018: Day 4 at altitude

Four of us are working in the bloods room to measure total blood volume, hematocrit and viscosity. We knew from previous reports that Andeans would have augmented total blood volumes and hematocrit levels compared to us lowlanders but seeing those bloods ourselves was staggering. ‘A hematocrit of SEVENTY-EIGHT per cent!’ a colleague yelled, astounded. For reference, a lowlander’s normal hematocrit is ~40%. (Fig. 1) An undeniable passion for physiology underpins collaborations like Global REACH.

The energy amongst the group drives impressive productivity and allows us to complete multiple studies in relatively restricted time periods. During the 2016 Nepal Expedition our team conducted 18 major studies, including a total of 335 study sessions in just three weeks at 5,050 m (further to multiple sea level and ascent testing sessions). This high-density data collection is relatively uncommon outside of field work and is only made possible by the vast breadth of technical fluency, specific expertise and research experience amongst the team. The expeditions allow us to not only answer our current questions but further breed a multitude of ideas for future study.

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‘We could answer that one next, Ethiopia 2020? Another Nepal expedition?’ Of course, these expeditions allow us as trainees and investigators to be productive, and to present and publish high-quality data and exciting findings. They strongly contribute to our development and career progression in academia. But what is undoubtedly most important is the greater aim of Global REACH: to understand altitude health on a ‘global’ scale. This collaboration and research ultimately aims to understand why chronic mountain sickness occurs, how different high-altitude communities have adapted (or maladapted) to low oxygen, and what might ultimately be done to improve the health of individuals exposed to acute or chronic hypoxia.

Stay tuned for Part 2 next week, or read the full article in its original version in Physiology News magazine.

Collaboration: Friend or Foe

This article originally appeared in our magazine, Physiology News.

By Mike Tipton, @ProfMikeTiptonUniversity of Portsmouth

It can be argued that, in the broadest sense, we would not exist without collaboration. It is also easy to argue that our future health, prosperity, and indeed, survival will be dependent on collaboration. However, collaboration is something of a conundrum. Its meaning and usage are so broad as to be almost meaningless, and as a concept it covers a multitude of scenarios, not all of them good. So how do we foster enduring, productive collaboration in science? 

Many people love the idea of collaboration, they pursue it with vigour, offering their services and proclaiming their interest in a project.Others are not keen on collaboration. For most, their view of collaboration largely depends on past experience or worries about future recognition. The problem is that there is a contradiction that runs through “collaboration”, right down to its definitions: a. The action of working with someone to produce something b. Traitorous cooperation with an enemy. Hopefully academic collaboration falls under the former rather than latter definition, but perhaps not always.

Collaboration in nature: lessons for scientists

There is no doubt that collaboration can be a driver for advancement, and even optimal advancement. This is easy to demonstrate in biological terms; for example over a billion years ago one bacteria became host to another, obtaining shelter in return for the production of energy from food and oxygen. Eventually the bacteria merged into a single cell that became the ancestral powerhouses of all multicellular life and the precursors to mitochondria. Today, examples of successful collaboration abound, from the African Oxpecker, and their aquatic equivalent, cleaner fish, to bacteria such as Lactobacillus that inhabit human intestines and help to relieve Irritable Bowel Syndrome, Crohn’s disease and gut dysbiosis. As Darwin said, “in the long history of humankind (and animal kind, too) those who learned to collaborate and improvise most effectively have prevailed.”

What can we learn from the animal kingdom that might help our collaborations with other scientists? The obvious lesson is that those collaborations between organisms that endure are symbiotic rather than parasitic. That is, both collaborators bring something to the relationship and both gain. To coin a cliché, the sum is greater than its constituent parts. Collaborations fail when, in one way or another, they become parasitic. Perhaps we should focus on “symbiosis” rather than “collaboration”?

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Figure 1. Collaborators seeing eye to eye: a symbiotic collaboration between the African Oxpecker and the African Cape Buffalo. One feeds, the other has parasites removed.

Scientific collaboration: the benefits

At one level, of course, all science is the product of a collaboration between colleagues within an institution, be they the technicians, students, academics or administrators that enable and conduct research. But what about collaboration across institutions? This is not an insignificant issue; even more so now than previously, successful collaboration is important for the advancement of research areas as well as scientific careers. As science moves unerringly towards complex, multifaceted studies employing advanced and highly specialised techniques, the need to collaborate nationally and internationally increases. This truth is increasingly being reflected in the published literature, where there is a positive relationship between the presence of international collaborating authors on top flight papers and citation impact (Adams & Gurney, 2016).

People are getting the message; as measured by co-authorship on refereed papers, international collaboration grew linearly from 1990-2005, or exponentially if international presentations are assessed (Leydesdorff & Wagner, 2008). In 1981 about 90 % of UK published research output was domestic, by 2014 this figure had fallen to less than 50 %; almost all of the growth in output in the last 30 years was produced by international co-authored collaborations (Adams & Gurney, 2016). In just the last two issues of Experimental Physiology we have published papers from 15 countries, and of the 22 papers published, 13 were collaborations between a total of 34 institutions. Leydesdorff & Wagner (2008) used network analysis to conclude that the growth of international co-authorship can be, at least in part, explained by the organising principle of preferential attachment (“the rich get richer”). Broadening collaboration should therefore be advantageous.

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Figure 2. Relative increase in international collaborative publications (articles & review indexed in Thomson Reuters Web of Science) since 2000 (Adams & Gurney, 2016). 

The major driver for collaboration is the need to share, be that ideas, equipment, facilities, techniques, resources or data. Without successful collaboration between experts within different fields, some major problems will either not be solved or will take much longer. For example, it is generally agreed that the battle against cancer cannot be won without such collaboration (Savage, 2018). Looking back, without collaboration we would have been less likely to know of the existence of the Higgs Boson or have sequenced the human genome. It is difficult to imagine the big questions of our time, such as understanding the working of the brain, the origin of the universe or the production of clean sustainable energy, being solved without interdisciplinary collaboration. The need for collaboration to provide the diversity of skills and techniques to answer these questions is paramount.  

The UK government is actively encouraging such collaboration through initiatives like the UK Research and Innovation (UKRI) Fellowships Programme. The Industrial Strategy Challenge Fund looks to build collaborations between academics and business. One of the six key areas is “Health and Medicine”. Research England recently invested £67m in 14 collaborative projects to “drive forward world-class university commercialisation across the country”.

Promoting collaboration: opportunities and threats

So, how do we create the conditions that might promote successful symbiotic collaboration within, but even more importantly, across disciplines? We start with an advantage; game theory (e.g. The Prisoners’ Dilemma) research tells us that humans display a systematic bias towards cooperative behaviour in preference to otherwise rational self-interest (Fehr & Fischbacher, 2003). So, we need to foster this altruistic inclination and minimise the threats to collaboration.

Publishing has a role to play in promoting collaboration; since the first issue of the Philosophical Transactions of the Royal Society was disseminated in 1665, potential collaborations have been promoted by the publishing industry reporting what could be done by other people working in the same field. A relatively recent development is the publication of datasets that can be examined and used by others, a new and as yet not fully evolved form of “collaboration”. On the other hand, publication can also be a barrier to collaboration: concerns about recognition of effort, authorship and ownership of ideas or data can introduce anxiety and suspicion. These problems can be minimised by early, open discussion, by scientists, and by journals giving high value to ideas. Following established guidelines for authorship should also help (e.g. International Committee of Medical Journal Editors Guidelines (2017).

Other threats to collaboration come in the form of international politics: BREXIT and access to EU funding, the rise of nationalism, travel bans, language barriers and difficulties in getting work permits. This is a constantly changing canvas within which scientists and leading institutions must lobby and advocate the crucial societal benefits of international collaborative research. Hopefully continued access to international and pan-continental research funding that demands international collaboration will help.  

The role of publishing in prompting collaboration is reinforced by scientific meetings where you meet, learn from and socialise with those working in your field. Having determined from the literature and scientific presentations those who you might work with, it is during social exchanges at meetings that you discover people you want to work with. One potentially negative consequence of subject-specific meetings is that they constrain the technical and academic cross-fertilisation, and consequent collaboration, that might be promoted at more multi-disciplinary meetings.

If we continue to use co-authorship with an individual from another institution as the index of collaboration, I have collaborated with 71 people from 15 countries over three decades (e.g. International Drowning Researchers’ Alliance- idra.world). As far as I can recollect, all of these collaborations, and subsequent close friendships, were forged in the conducive atmosphere of a scientific meeting. It follows that any decline in funding to attend scientific meetings will stifle potentially critical collaborations. It also follows that although, as noted above, it is possible to encourage or require collaboration through targeted funding calls, in the absence of such funding it is very difficult to “administer” long-lasting productive collaborations into existence from nowhere. They have to evolve naturally, through interpersonal contact and understanding of the skill sets and capabilities of different people.

That is not to say that people who do not get on personally cannot collaborate; it is simply that the holistic experience and durability of the collaboration is likely to be diminished. Because, in the end, it is about spending time with those you respect, like, need and can communicate freely with. As in so many other things, Shakespeare had it about right,

Those friends thou hast, and their adoption tried,

Grapple them unto thy soul with hoops of steel

For a scientist, as well as society in general, the benefits of collaboration go far beyond science.

Acknowledgements

I would like to thank Alex Stewart, Sarah Duckering and Joe Costello for their contributions to this article.

 

Early to bed and early to rise… makes a teen healthy, wealthy and wise? (Part 2)

By Gaby Illingworth, Rachel Sharman & Russell Foster; @OxTeensleep, @gabyillingwort1, @DrRachelSharman, @OxSCNi

To the possible dismay of parents hoping to start the family day bright and early, teenagers hit the hay and wake up at increasingly later times during adolescence – a delay of between one and three hours compared to pre-pubertal children.

Teenagers struggle to fall asleep early but still need to wake up for lessons during the school week, which contributes to a reduction in time spent asleep. At the weekend, the morning hours may well be spent snoozing to “catch-up” on lost Zzz’s.

In 2015, the National Sleep Foundation recommended that teenagers, aged 14 to 17 years, should be getting eight to ten hours of sleep a night. However, across the globe, teenagers are routinely not getting enough sleep, with older adolescents more likely to have insufficient weekday sleep than early adolescents. One of the consequences of insufficient sleep is that sleepiness during the day is common in this age group.

Sleep researchers have suggested some mechanisms behind this change in teenagers’ sleep timing.

How teenagers become owls: slower clocks, increased light sensitivity, or decreased sleep pressure

Although we don’t know why adolescent sleep changes, we do know that changes occur in the two processes which govern sleep – the circadian rhythm and sleep/wake homeostat. (Catch up on these two concepts in our previous post.)

The teenage biological clock has been proposed to run more slowly at this age, driving their sleep timing later, meaning their chronotype becomes more owl-like.

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From DIVA007 on Flickr

Another suggestion is that their biological clock might be more sensitive to light in the evening (delaying sleep) and less sensitive in the morning (making them wake up later).

Adolescent sleep pressure is also thought to accumulate more slowly during the day, making them less tired when they reach the evening.

Jetlag without leaving the country

We know what jetlag feels like when we travel across time zones. Our internal time takes a while to adjust to the new external time.

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Teenagers experience something similar with ‘social jetlag’: when their internal time (chronotype) is misaligned with social time (school commitments). At the weekend, they are more likely to be able to sleep according to their chronotype than during the school week. This misalignment of sleep/wake timing has been shown to associate with poorer cognitive functioning.

To blame the bright screens or not?

Teenagers’ lack of sleep is not all down to physiology. They, just like adults, may be engaging in behaviour that isn’t conducive to sleeping well.

The effect of light exposure on sleep has received increasing attention with the proliferation of electronic device use in recent years. However, the results are mixed.

One study on young adults asked individuals to read an e-book at maximum intensity under dim room light for around 4 hours (18:00–22:00) before bedtime on five consecutive evenings, whilst the control group read a printed book.

While the study concluded that those that read the e-book took longer to fall asleep, had lower morning alertness, and a delay of the circadian clock compared to reading a printed book, the effects were relatively small. Those participants who read e-books took only 10 minutes longer to fall asleep (Chang et al., 2015).

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As a result, some caution needs to be exercised when the press reports that reading an e-book before bed has unintended biological consequences that may negatively affect performance, health, and safety.

Nevertheless, the impact of using electronic devices prior to sleep does seem to be important. In a large US survey, adolescents were shown to have increased the time spent using electronic media devices from 2009 to 2015.

This was correlated with a decline in sleep duration (Twenge et al., 2017), and light from such devices has been blamed. Such studies have encouraged the use of in-built or downloadable applications that can dim the brightness of screens and/or reduce the light emitted.

Light interventions are now being considered as a tool for adolescents experiencing difficulties with sleep, including reducing their exposure to evening light and increasing morning light to advance the clock to a time more suited for school.

Unfortunately, the evidence showing that such interventions can be helpful is lacking. Furthermore, it is important to stress that game use, social media, and watching TV are all likely to be cognitively arousing so teens may simply feel like staying up when they use electronic media devices.

As a result, disentangling the light effects versus the alerting effects of devices is complex and awaits good experimental studies.

Highly caffeinated

 

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From Austin Kirk on Flickr

Caffeine is a stimulant with a half-life of approximately six hours in healthy adults (meaning that half of it is broken down in our bodies in six hours). It works by preventing the molecule adenosine, which promotes sleep, from having its effect in the brain, thus promoting wakefulness.

Teenagers are advised to consume no more than 100mg of caffeine per day, yet highly-caffeinated energy drinks are popular among teens. Many energy drinks contain higher caffeine levels than 100mg in a single can. Consuming caffeine later in the evening, or consuming it excessively throughout the day may be another contributory factor to delayed sleep.

Correspondingly, the National Sleep Foundation 2006 ‘Sleep in America’ poll found that adolescents who drank two or more caffeinated beverages each day were more likely to have insufficient sleep on school nights, and think they have a sleep problem, than those who drank one beverage or fewer.

We don’t need no early morning classes

School-based interventions are now underway that aim to improve teenage sleep. Sleep education programmes inform teenagers about the lifestyle factors that may be affecting their sleep and how they can improve sleep hygiene.

There is also a movement to delay school start times to better suit the adolescent clock by giving teenagers the opportunity to sleep at hours more aligned with their chronotype and reduce their social jetlag.

Given all the research, one could suggest that “early to bed, later to rise, may help the teen be healthy, wealthy and wise” would be a better amendment to the age-old quote for our average teenager.


References

Chang, A.M., Aeschbach, D., Duffy, J.F. and Czeisler, C.A., 2015. Evening use of light-emitting eReaders negatively affects sleep, circadian timing, and next-morning alertness. Proceedings of the National Academy of Sciences112(4), pp.1232-1237.

Twenge, J.M., Krizan, Z. and Hisler, G., 2017. Decreases in self-reported sleep duration among US adolescents 2009–2015 and association with new media screen time. Sleep medicine39, pp.47-53.

Early to bed and early to rise… makes a teen healthy, wealthy and wise? (Part 1)

By Gaby Illingworth, Rachel Sharman & Russell Foster; @OxTeensleep, @gabyillingwort1, @DrRachelSharman, @OxSCNi

Teenagers are well-known for routinely staying up late and then having a long lie-in. Sometimes this is put down to laziness or their transition from childhood into ‘Kevin the Teenager’.

However, there are biological reasons which help explain why teenagers are late to bed and late to rise, and why they might not actually be getting enough sleep to make them healthy, wealthy, and wise.

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Created by Matteo Farinella

Sleep matters. A wealth of evidence supports the importance of sleep for our physical, mental, and emotional functioning. Insufficient sleep has been linked to problems with attention, creativity, memory and academic performance, as well as increased impulsivity, and difficulties with mood regulation.

Sleep: a double-act

Sleep is driven by two processes working in tandem: the circadian rhythm and the drive for sleep (sleep homeostat).

The circadian rhythm is a roughly 24-hour cycle of changes in physiology and behaviour, generated inside our bodies. These rhythms come from certain genes being turned on and off (called clock genes) in almost all cells throughout the body. The master clock, (the suprachiasmatic nucleus in the brain), coordinates the rhythms within these cellular clocks.

The second system involves a balancing (homeostatic) process. Put simply, the longer you have been awake, the greater the need for sleep will become. The drive for sleep is thought to stem from a build-up of various chemicals (in the brain) while we are awake. For example, adenosine is a building block of our body’s energy currency (ATP), so it builds up as a consequence of energy use in the brain. Adenosine inhibits wake-promoting neurons and stimulates sleep-promoting neurons. As we sleep, adenosine is cleared and sleep pressure reduces.

Sometimes the two systems oppose each other. For example, we would feel very sleepy mid-afternoon due to increasing sleep pressure if it were not for the circadian drive for wakefulness.

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Sleep occurs when the circadian drive for wakefulness ends and the drive for sleep kicks in. Then when the ‘sleep debt’ you have accumulated during the day has been re-paid (and so sleep pressure is reduced), and the circadian drive for wakefulness is sufficiently strong, we wake up.

Why some people don’t like mornings

Some of us love to burn the midnight oil, while others schedule in regular morning runs. The technical term for your preferred sleep/wake timing is chronotype, what we colloquially refer to as being an owl or a lark. You are owl if your biological clock runs slower and a lark if it runs faster.

We don’t run on 24 hours

While our day runs on 24 hours, for most of us, our internal clocks don’t. Therefore, our internal clock needs to be adjusted daily by external time cues such as light intensity. The master biological clock receives light signals direct from cells in the retina, which are most sensitive to blue light.

Dusk triggers the production of melatonin (the ‘vampire hormone’). Although not a sleep-inducing hormone, melatonin serves as a cue for rest in humans, with levels increasing as we approach sleep and remaining high during the course of the night.

In contrast, dawn light suppresses melatonin levels. The circadian clock responds differently to light depending on the timing of exposure, so that morning light advances the clock (making us get up earlier) and evening light delays the clock (making us get up later the next day).

As well as playing a role in sleep regulation via the circadian clock, light affects how alert you feel. You may have noticed that bright light increases your alertness, so relatively bright light before bedtime will increase the likelihood that you will feel sleepier later.

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Stay tuned for next week’s blog about how changes in these systems affect teenage sleep.

The female athlete: A balancing act between success and health

By Jessica Piasecki, Manchester Metropolitan University, UK, @JessCoulson90

A longer version of this article originally appeared in Physiology News.

There is a very fine line between training, competition, and recovery for the elite athletes (1). For female athletes, they have an extra balance to take into consideration: the menstrual cycle.

The monthly cycles

The menstrual cycle is a natural process and is essential to maintain bone health and fertility. It can start from the age of 12 and continues until the onset of menopause around the age of 49-52.

The cycle occurs over a period of 28 days. The first 14 days are known as the follicular phase. During this phase, around day 10, the hormones oestrogen, LH (luteinizing hormone) and FSH (follicular stimulating hormone) rise, reaching their peak around day 14.

LH reaches a level double than that of both oestrogen and FSH. After day 14 LH levels rapidly drop off while oestrogen and FSH fall off more slowly, over a 5 day period. The second 14 days are known as the luteal phase and there is a gradual increase in another hormone, progesterone, which reaches a peak around day 22 and returns to base levels at day 28.

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Bone stability and structure

Of these three hormones, oestrogen is a key regulator of bone resorption, without oestrogen there would be an excess of bone being broken down over new bone being formed. Bone is in a state of constant turnover, with the help of two types of bone cells (osteoblasts and osteoclasts). Osteoblasts are involved in bone formation, while osteoclasts are involved in bone resorption.

Bone resorption occurs at a much higher rate than formation; bone resorption takes just 30 days whereas the bone remodelling cycle takes 4 months. Therefore, a slight imbalance can lead to a bone fracture very quickly (2).

More is not always better

Elite female athletes, particularly those involved in sports that usually adopt a leaner physique with low body fat, are at a greater risk of disordered eating. The reasons for this disordered eating could be external pressures from teams, coaches and sponsors, or the athletes themselves having the belief that the leaner and lighter they are, the quicker they will be. These pressures may also cause the athlete to push their body to further extremes.

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Without the necessary energy intake, the menstrual cycle will most likely become irregular and eventually cease (which is known as amenorrhea). Amenorrhea causes the levels of oestrogen to become reduced, leaving a disproportionate ratio of osteoblasts and osteoclasts, and a higher rate of bone resorption.

This may ultimately lead to bone injuries, (the precursor to osteoporosis), or even osteoporosis at a very young age, making any further career achievements even more difficult.

These three symptoms (disordered eating, amenorrhea and osteoporosis) became more prevalent in the 1990s and were termed ‘The Female Athlete Triad’ in 1997 by the American College of Sports Medicine. It has been estimated that only 50% of trained physicians are knowledgeable about the female athlete triad (3). More recently the triad has been regrouped within a term known as RED-S (Relative energy deficient syndrome); deemed to result from continual disordered eating. Being in a state of energy deficiency for a long duration can disrupt many processes within the body, including the cardiovascular, digestive and hormonal . Redefining the RED-S also allows male athletes who present with similar issues to be included (4).

Current research has looked at the differing effects of the components of the triad on injuries, and bone and muscle health. At Manchester Metropolitan University, we have carried out our own research on some of the UK’s most renowned female endurance runners, investigating the effects of altered menstrual cycle on bone health. Athletes with amenorrhea presented with a greater endocortical circumference (the outer circumference of the inner cortical bone in the tibia (lower leg) and radius (forearm) than controls. Only the athletes with regular menstrual cycles (eumenorrheic) had a greater cortical area, in the tibia and radius, compared to controls. The athletes with amenorrhea had thinner bones (i.e. larger but not denser). We are working to better understand the issues, so accurate diagnosis will become more frequent.

What we really need is education at a young age, as most athletes become familiar with the triad only once they have been diagnosed with a bone injury. If athletes are made aware of the symptoms and issues around the triad before they occur, then nutrition and menstrual cycles can be more closely monitored as they progress through their athletic careers.


Read the full-length version of this article in our magazine, Physiology News.

References

  1. Barnett, A (2006). Using recovery modalities between training sessions in elite athletes does it help? Sports Med (36), 781-96
  2. Agerbaek, M. O., Eriksen, E. F., Kragstrup, J., Mosekilde, L. and Melsen, F. (1991) A reconstruction of the remodelling cycle in normal human cortical iliac bone. Bone Miner, 12 (2), pp. 101-12.
  3. Curry, E, Logan, C, Ackerman, K, McInnia K, Matzkin, E (2015) Female athlete triad awareness among multispecialty Physicians. Sports Med Open. 1:38.
  4. Tenforde, AS, Parziale, A, Popp, K, Ackerman, K. (2017) Low Bone mineral density in male athletes is associated with bone stress injuries at anatomic sites with greater trabecular composition. Am J Sports Med. DOI: 10.1177/0363546517730584

Exercise, stress and Star Wars: Best of 2017 roundup

Happy New Year! In 2018, we look forward to more physiology fun, and to giving you an insight into the exciting new developments in the Science of Life!

Physio-what, you ask? Take a look at our animation below introducing physiology! Scroll down to find out more about a centuries-old shark patrolling the deep Arctic Ocean, how being active gives children’s hearts a head start for life, and why it’s time scientists took back control from exercise gurus, in our best of 2017 roundup!

1. Exercise scientists should fight the exercise gurus

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Exercise gurus build strong rapports with their audience to encourage commitment, but they will often simplify a large body of scientific evidence to back up their advice.

In this post, Gladys Onambele-Pearson and Kostas Tsintzas discuss the risks of letting exercise gurus disseminate exercise science to the public, and why it may be time for scientists to become the actual celebrities.

2. The Myth of a Sport Scientist

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There is a mismatch between the perceptions and reality of what a sport scientist is and what skills this career entails: just because exercise scientists use models of sport performance, exercise bouts or physical activity sessions, doesn’t mean that there aren’t complex scientific skills, theories, analytics and techniques behind the work.

Read more from sport scientist Hannah Moir in this post.

3. Shark Diary, Episode I: On the trails of the Greenland shark

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How do you keep lab chemicals cool when there’s no fridge in your room? Well, if you’re in chilly Denmark, you could just hang them outside your window.

Holly Shiels did just that in Copenhagen, on her way to Greenland to join a team of physiologists on a shark research mission. Their aim was to gather data on the physiology of the Greenland shark. Clarifying how these animals reach hundreds of years of age without developing diseases associated with human ageing, like cancer and heart disease, could lead to new therapies down the line, and understanding shark physiology is also important for their conservation.

Read more about the mission in this post, and check out watch below to see the researchers braving the icy waters of the North Atlantic and releasing a tagged Greenland shark.

4. Breath of the Sith: a case study on respiratory failure in a galaxy far, far away

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Have you always wondered what actually is going on behind the mask? Darth Vader’s acute respiratory failure appears to be the consequence of a number of factors, including direct thermal injury to the airways, chemical damage to the lung parenchyma caused by inhalation of smoke and volcanic dust particles, carbon monoxide poisoning, as well as secondary effects to his severe third degree burns, which seems to cover ~100 % of his total body surface area.

Read on as Ronan Berg and Ronni Plovsing make a tongue-in-cheek diagnosis of the numerous respiratory ailments of everyone’s favourite Sith Lord.

5. Exercise now, thank yourself later

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Exercise is good for the heart, but the benefits fade soon after we stop training… or so we thought. Studies so far have focused on adults, but research published last November in The Journal of Physiology reveals that exercise in early life could have lifelong benefits for heart health.

This is because young hearts are able to create new heart muscle cells in response to exercise, an ability that is mostly lost in adulthood. Glenn Wadley, Associate Professor at Deakin University and author of the study, explains the findings in this post, and makes the case for children to get active!

As if that wasn’t enough reason to exercise, being active is one of three tips that can help relieve the stress we feel for instance at the approach of exams. Watch our animation below to find out more about what stress does to our bodies, and start making good on those New Year resolutions!