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

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Sleep Deprivation Benefited Our Ancestors, Yet Harms Us Now — But Staying Fit May Help Us Cope

Less Sleep Needed: An Ancestral Gift

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Humans need less sleep than our closest evolutionary relatives. However, we often sleep less than we need. Needing less sleep is a consequence of our ancestors’ choices to remain awake longer — a behaviour that led to evolutionary benefits. Sleeping less than we need is the result of our modern-day choices to remain awake longer, but in this case, the behaviour is detrimental to our health and well-being. Our research, however, finds that fitness may be a helpful tool for coping with sleep deprivation.

Less Sleep Available: A Modern 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 form of unbearable insomnia that changed his personality. He referred to it as a "karmic payback" in a 2018 interview with NPR’s Hidden Brain podcast.

The year 1964 was a time when the necessity of sleep may not have been preached enough as 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.

Countermeasures Against Sleep Deprivation

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

Policies must intervene to address sleep-related issues. For example, pushing the school start time later to match teens’ circadian rhythm (teens are not night owls by choice) or abolishing daylight savings, reducing work hours for essential professions, implementing evidence-based regulations for nightshift work, defining and normalizing sleep health.

Protective Power of Fitness

A recent study by our team of researchers at McGill University’s MEMORY lab may have identified a protective factor. The research team — ironically while getting sleep-deprived — showed that people who were more physically fit performed better at a memory task compared to people with lower fitness levels after a night of sleep loss.

The fun part was when one group of participants spent one night in the lab staying awake, without caffeine, doing mild activities and a lot of talking with the researchers who supervised them. Participants were asked to stay awake for 30 hours, which is brutal but distressingly common among essential workers.

Exercise Caution

We cannot conclude that higher fitness is a cause of memory protection during sleep deprivation. Other healthy habits of fitter participants such as good sleep hygiene, higher cognitive reserve, and healthy diet may have contributed to their better 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 dealing with the epidemic.

Conclusion

Compromising sleep has not served our ancestors and us equally. Nature’s incessant drive to choose sleep underscores its irreplaceability. But today, if you decide to run a wake-a-thon, it is advisable to stay fit!

FAQs

Q: Why do we need less sleep than our ancestors?
A: Our ancestors traded sleep for productive nightly activities like exchanging cultural information to gain social and individual learning, watching for predators, and strengthening bonds with peers.

Q: What are the consequences of sleep deprivation?
A: Sleep deprivation impairs communication between brain regions and brain blood flow, damages brain wiring, and makes a young brain look like an aged brain.

Q: How can we better cope with sleep loss?
A: Considerable research shows that sleep deprivation can be mitigated by implementing policies that address sleep-related issues, such as pushing school start times later, abolishing daylight savings, and reducing work hours for essential professions.

Q: Is fitness a helpful tool for coping with sleep deprivation?
A: A recent study found that people who were more physically fit performed better at a memory task compared to people with lower fitness levels after a night of sleep loss.

Q: What are the implications of this study?
A: The findings suggest that fitness may be a helpful tool for coping with sleep deprivation, and that aerobic exercise training can protect against the detriments of sleep deprivation.