SLEEPING PATTERN OF PRIMATES
Primates, these are the so-called supreme animals: humans, monkeys and half apes. In evolutionary terms, we're linked. But just as our brains and physique have evolved, our sleeping patterns have evolved.
Most monkeys are diurnal animals and therefore live according to a light-dark rhythm, just like us. Moreover, research has already indicated that monkeys - and actually most mammals - also go through REM sleep and non-REM sleep. Moreover, they also dream, even if they can't tell you about it. Did you know that they can even suffer from sleep disturbances like humans?
A big difference, however, is that monkeys sleep in shorter periods of time. They don't sleep 8 or 9 hours at a time like humans do. However, they are active for about twelve hours a day, with a sort of lunch break during the day and a period of inactivity at night.
EVOLUTION IN DAY AND NIGHT RHYTHM
So we can assume that our ancestors had a similar sleeping pattern to that of monkeys. There are several reasons for changing that rhythm. Just think of the invention of fire and electrical light. Because of this we prolong the days as it were and we can still be 'active' after sunset.
So we rest less than monkeys and a lot of other mammals, but we do so in longer periods of time. Why are we doing this? Well, we have fewer dangers to fear at night like predators lurking in wait and - ordinarily - we don't have to hunt to be able to eat.
DAYTIME AND NOCTURNAL ANIMALS
How is it that not all animals on earth have the same sleeping pattern? The fact that there are day and night animals is actually a clever trick of nature: the pressure of natural selection. The animals that are most active at night are physically equipped for this.
After all, they have to find their food or prey at night. They therefore have good night vision, better hearing, long whiskers or even a sonar system (e.g. bats). It is not without reason that many insectivores are nocturnal animals. Their food consists of beetles, worms, spiders, etc. and those are the animals that like the dark, a lower temperature and moist soil. Now, that' s a good thing...