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Ape Beds, Dinosaurs, and Napping with Half a Brain

Should you ever have to give a presentation at work, for your own sake—and that of the conscious state of your listeners—if you can, avoid the midafternoon slot.

All living beings in the animal kingdom share the bond of sleep. In fact, sleep is considered to be universal. However, there are many differences across species in the manner in which sleep occurs. Some animals sleep for a few minutes, some with half a brain at a time, and some for the greater part of the day.

There are two types of sleep stages that involve eye movements: non–rapid eye movement, or NREM, sleep, and rapid eye movement sleep, or REM.

There are differences in NREM and REM sleep depending on the animal. Humans, on average experience 75-80% NREM sleep and 20-25% REM sleep. Most adults in industrialized nations take a longer night slumber, which usually lasts for about seven hours. However, people of different tribes which do not live in modern society sleep for approximately seven hours during the night, but also take a one-hour nap in the afternoon.

The need for an afternoon nap is biological. Humans experience a decrease in alertness during the mid-afternoon hours, which has been recorded many times in history. This split in the amount of sleep is named biphasic sleep because it occurs in two (bi) phases.

Quality REM sleep, mentioned previously, is necessary for humans to be able to control and regulate their emotions on a daily basis, and also to think and act logically and reasonably. Moreover, one of the crucial evolutionary benefits of REM sleep is humans’ creativity. Deep NREM sleep helps in the creation of long-term memories, whereas REM is responsible for making connections between pieces of information, i.e. associations.

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