Sleep deprivation benefited our ancestors, yet harms us now — but staying fit may help us cope

Humans need less sleep than our closest evolutionary relatives. However, we frequently sleep lower than we want.

Needing less sleep is a consequence of our ancestors’ selections to stay awake longer — a behaviour that led to evolutionary advantages. Sleeping lower than we want is the results of our modern-day selections to stay awake longer, but on this case the behaviour is detrimental to our health and well-being. Our research, nonetheless, finds that fitness could also be a helpful tool for coping with sleep deprivation.

Less sleep needed: An ancestral gift

Our ancestors traded sleep for productive nightly activities like exchanging cultural information to realize social and individual learning, looking ahead to predators and strengthening bonds with peers. This learning had evolutionary advantages and led natural selection to favour shorter sleep durations. Humans are outliersnonetheless, needing sleep for less than seven hoursfar lower than the predicted 9.55 hours of sleep for a primate with similar traits to ours.

Our ability to thrive with longer waking hours is regarded as possibly as a result of our highest proportion of efficient, dreamy REM sleep amongst all studied primates and brain anatomy changes that facilitate essential housekeeping functions of sleep (like removal of poisons) in a shorter span. This ancestral selection to sleep less was worthwhile (although some speculate that it can also have had drawbacks).

Less sleep available: A contemporary misery

In an extreme example of sleep deprivation, in 1964 Randy Gardner broke the world record by staying awake for 11 days. His wake-a-thon bit him back years later in the shape of unbearable insomnia that modified his personality. He referred to it as a “karmic payback” in a 2018 interview with NPR’s podcast.

The yr 1964 was a time when the necessity of sleep may not have been preached enough because the role of sleep in processing emotions and memories, preserving the body’s immune and hormonal functions, and wringing out its toxins was less well understood.

Today, despite knowing its advantages, humans still willingly sacrifice sleep. We forgo sleep to tug an all-nighter in preparation for an exam or a gathering, binge-watch TV shows, conform to the sleeplessness trend of the fashionable culture or scroll through social media.

Sleep shouldn’t be a luxury for individuals who must face sleep disorders, socioeconomic sleep disparitylatest parenthood or work obligations of pilots, health-care staff and others with irregular hours. One-third of Americans and Canadians are wanting sleep.

Considerable research shows that sleep deprivation impairs communication between brain regions and brain blood flow, damages brain wiring and makes a young brain seem like an aged brain. For humans, compromising sleep to be productive is counterproductive. It compromises our greatest performance, attention, decision-making abilities and memory. We risk road and industrial accidents, psychiatric illnesses, dementia and cardiovascular diseases, costing governments billions of dollars annually.

For our evolutionary ancestors, sleep was costly since it risked being vulnerable to predators and limited the time to interact in productive activities. Today it’s the shortage of sleep that is dear because sleep is crucial.

Sleep research pioneer Allan Rechtschaffen noted: “If sleep doesn’t serve a fully vital function, it’s the largest mistake the evolutionary process has ever made.”

Countermeasures against sleep deprivation

An easy fix is to sleep more. But it’s a far-fetched goal. Today, getting even an hour or two of additional sleep is difficult.

Policies must intervene to handle sleep-related issues. For example: pushing the college start time later to match teens’ circadian rhythm (teens should not night owls by selection) or abolishing daylight savingsreducing work hours for essential professions, implementing evidence-based regulations for nightshift work, defining and normalizing sleep health.

But until policies change, how can we higher deal with sleep loss?

Protective power of fitness

A recent study by our team of researchers at McGill University’s MEMORY labled by master’s student Beatrice Ayotte, can have identified a protective factor. The research team — sarcastically while getting sleep-deprived — showed that individuals who were more physically fit performed higher at a memory task in comparison with individuals with lower fitness levels after an evening of sleep loss.

Fitness was measured as the flexibility of the participants’ heart and lungs to provide oxygen and their muscles’ ability to make use of it while exercising. This is known as cardiorespiratory fitness, versus muscular fitness. For this, within the gym-like laboratory, healthy 18-to-35-year-olds biked with increasing resistance until exhaustion. They wore masks with tubes hooked to a pc that measured VO₂peak — the amount of peak oxygen consumption. A better VO₂peak indicates higher fitness.

The fun part was when one group of participants spent one night within the lab staying awake, without caffeine, doing mild activities and a whole lot of talking with the researchers who supervised them. Participants were asked to not sleep for 30 hours, which is brutal but distressingly common amongst essential staff.

After their wakeful period, participants viewed some images. Four days later, they got a surprise memory test. Participants who remembered more images scored higher on this memory task.

Sleep deprivation, as expected, had significantly decimated participants’ memory, as reflected of their poorer memory scores in comparison with the well-rested group. But what’s interesting is that, within the sleep-deprived group, many of the high memory scorers were also highly fit. This indicates that fitter people had some leverage within the sleep-deprived situation.

One interesting finding is that the association between VO₂peak and memory scores was not explained by the participants’ levels of fatigue and a focus. So it was not that fitter people could endure more fatigue during sleep deprivation and subsequently performed well. Fitness was working of their favour another way.

Research has shown that individuals with higher cardiorespiratory fitness are inclined to have higher brain connectivity and cognition. These brain changes could possibly be certainly one of the numerous mediators of the association present in this study.

Exercise caution

We cannot conclude that higher fitness is a reason for memory protection during sleep deprivation. Other healthy habits of fitter participants similar to good sleep hygienehigher cognitive reserve and healthy weight loss plan can have contributed to their higher memory performance despite sleep loss.

However, animal research has shown that aerobic exercise training — which increases cardiorespiratory fitness — can protect against the detriments of sleep deprivation. These findings synergize with our own and suggest possible forward steps in coping with the epidemic.

Compromising sleep has not served our ancestors and us equally. Nature’s incessant drive to decide on sleep underscores its irreplaceability. But today, for those who resolve to run a wake-a-thon, it’s advisable to remain fit!