If you fall asleep at 8pm and wake up at 4am with 8 hours of sleep why do you feel extremely tired by 10am, but if you go to sleep at 11pm and wake up at 7am you can stay up all day without feeling very sluggish? Does it have something to do with waking up while it’s still dark?
In: Biology
Depends on your circadian rhythm (sleep cycle is a circadian rhythm.) A circadian rhythm is essentially your body cycling in tandem with the sun, so every 24 hours.
Some people for example are “night owls,” their natural sleep cycle tends to be early hours of the morning (2-6 am) until 10am-2pm.
A theory behind why people are night owls is that in the hunter gatherer societies some people would have to stay awake to alert the tribe to any predators or other threats. Which of course increases the likelihood of the tribe as a whole to pass on their genes. It’s been argued that it’s a remnant of those times.
Most people however have a natural sleep cycle, which is the classic 10-11pm until 6/7 pm. That’s mostly due to us evolving to not be nocturnal.
In essence, having people with different sleep cycles, helped protect the tribe. One study showed that Europeans are far more likely to carry the gene. This could possibly be due to how far North Europe is. For example, London is further North than the vast majority of Canadian cities, yet it’s one of the most southern British cities. That means that in December day light is a little over 6 hours long. Which means there is far more time where the tribe would remain vulnerable.
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