Irregular Sleep Patterns Are Explained by Evolution

Are you wondering why you tend to go to sleep late, while others seem to have it more easily with maintaining a more organized sleeping schedule? Our ancestors are to blame for this, and this behavior originates back in hunting times, when humans needed to keep an eye on prey.

Humans stayed up late to monitor hunting

Having irregular sleep patterns would have constituted an advantage during ancient time, since it could be synchronized with a hunting schedule. Back then, humans lived and hunted in groups, and at least one person needed to be awake constantly to look for beasts.

To understand how ancient humans slept, researchers from the University of Toronto, Canada, analyzed a tribe from Tanzania, Hazda, which is still leading a hunter-gatherer way of life. For a period of 20 days, they saw how someone was awake almost all the time.

The entire study, published in the journal Proceedings of the Royal Society, monitored around 200 hours of sleep. All the members of the tribe managed to be asleep all at the same time only for 18 minutes, which makes up for only 0.001 percent of the entire monitored period. On average, eight adults were awake and active during any moment of the night.

Sleep patterns change as you get older

Other previous studies showed between 40 and 70 percent of a person’s body clock was influenced by genetics. The environment the person lives in is also important, but age is another vital factor in determining sleep patterns.

Therefore, all variations in a sleeping schedule are given mainly by age. When you’re young, you are more likely to be more productive during later hours in the day. As you get older, you become more active earlier in the morning.

Since humans change their sleeping behavior as they get older, it is important that tribes should have more elders who can take care of everything and keep an eye on things while youngsters are resting. Also, it seems that older people are more fit to survive from an evolutionary point of view, precisely because of these shifting sleep patterns.
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