How Has Sleep Evolved Over Time?

Though animal and human sleep habits vary widely, there is one commonality – all animals must rest for survival. When animals (including humans!) are sleep deprived, they have slower responses. In the wild, where life and death situations are the daily norm, this could cause serious problems.

Drowsiness poses dangers for humans, too, but we do have things a little easier. We can choose not to engage in high-risk activities like driving while we’re tired, but an animal like a rabbit or deer can’t choose whether or not it will need the energy to outrun a predator. This is why sleep is an essential evolutionary survival trait.

Everybody Sleeps

It sounds like the beginning of a children’s bedtime story, and it’s true! All animals, including humans, are dependent on high-quality sleep in order to survive and thrive. Here are a few fun facts about animal sleeping habits:

1. Fish snooze! Sleep varies by species of fish and some may rest deeper than others. In fact, while a fish like a Spanish Hogfish is asleep, you can lift it up to the surface without disturbing its slumber.
2. Average animal sleep times vary: horses may sleep 5-7 hours per day whereas koalas can rest in the cool shade of a tree for up to 20 hours.
3. Hedgehogs are nocturnal, meaning they are awake at night. During the day, these little balls of quills can sleep for up to 18 hours. In winter, they can lower their body temperature in order to hibernate through the cold months.
4. Migratory birds with long travel ahead of them may not be able to rest in a nest. Instead, they have evolved to let one half of the brain rest, while the other works. The working side of the brain maintains muscle movements

Why Do We Sleep?

Just as animal sleep has evolved, so too has sleep theory. Early sleep theory described our nightly rest as “energy conservation.” The theory presented the idea that animals (including humans) hiding in dark spaces and resting in a sleep-like state spares energy, giving them a higher chance to survive during active hours.

According to current research, sleep deprivation leads to impaired attention, decision-making, short-term memory dysfunction, long-term memory impairment, and poor mental health. Like all animals, without proper sleep we cannot thrive to survive. We need regular, high quality sleep so that our brains are ready to learn new information and overcome the daily challenges of life. Napping isn’t just a self-care hack – it’s a survival skill!

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History of Human Sleep Habits

Take it back to elementary school: think about the early civilizations you learned about. You may have skipped over the history of sleep in social studies class, but we are diving deep into it here! Those early humans most likely slept in ground-based nests or nooks, made of soft materials, like plants, grasses, and animal furs. These bed areas would have been built into caves, near trees, or other protected areas. In some areas, evidence suggests that early humans created sleep mats out of grass and ash, which had the added benefit of warding off insects during the night. With the evolution of sleep, our sleep environments and sleep hygiene have also evolved. Here are a few sleep technology innovations that occurred along the way:

1. It gets hot along the Nile river, sothe ancient Egyptians got creative to keep cool. By soaking their sheets or blankets in water, they would keep cool all night.
2. Rome wasn’t built in a day, but it may have been built thanks to the power of a good nap! The Romans adopted biphasic sleep practices, which involved a long overnight sleep period coupled with a shorter daytime nap.
3. During the Middle Ages in Europe, a new kind of biphasic sleep pattern emerged. Many people would sleep for 4-5 hours, then wake for another 1-2 hours of nightly prayers and work. After completing necessary chores like adding wood to the fire, there was time for socializing and leisure activities before returning to sleep.
4. The Industrial Revolution shaped our sleep into what it is today, introducing long working hours, electricity, and household lamps. This established our current pattern of sleeping in one long overnight stretch, with occasional naps when we can fit them in 

Our sleep hygiene is still evolving. With advances in sleep technology, humans are trying to create space for better, deeper, more restful sleep. On the other hand, with smart phones at our fingertips and artificial lighting everywhere we turn, technology can also make it harder to stay in touch with our bodies’ natural circadian rhythms.

Still, our sleep environments have gotten a lot comfier since ancient times. We can simulate the peace and quiet of nighttime at any time of day with room darkening curtains and white noise machines. And instead of relying on water-soaked blankets like the ancient Egyptians did, we can keep off the heat with breathable sheets, or even cooling weighted blankets like our Tree Napper. With these and many other helpful sleep aids, we are now intentionally finding ways to get the rest we know we need whenever we can – and that’s a cause for celebration!