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Sleep and Dreams · entry 15 of 52
A short nap of around twenty minutes usually ends before the deepest sleep stage begins.
The longer version
A brief doze usually stays in the light drowsy stages, since the descent into slow-wave sleep takes some time. Heart rate and breathing remain close to waking levels during such light sleep, and waking from it leaves most people clear-headed, with none of the heavy disorientation that follows a deeper awakening.
The popular twenty-minute figure matches the point before slow waves take over, though the exact boundary differs between individuals and depends on how much sleep pressure has built. Short midday dozing is common across cultures, and similar brief bouts appear in the daily routines of many animals, which rest repeatedly rather than in one long block.
Where this entry sits
This collection gathers curious details about sleeping and dreaming, from nightly brain stages and body clocks to naps, yawns and unusual animal habits. It also covers how bedtime customs have changed across centuries, without offering any advice. The full list sits on the Sleep and Dreams page, where every entry is listed in order.
More From Sleep and Dreams
Eight more entriesNaps longer than half an hour are more likely to end during deeper sleep.
Read 17Many cultures once treated sleep as two separate blocks separated by a wakeful hour.
Read 18Before electric lighting, people in many regions slept longer in winter than in summer.
Read 19Electric lighting changed bedtime habits by making evening activity possible for many more hours.
Read 20People once relied on roosters, church bells and night watchmen to know when to wake.
Read 21Beds in ancient Egypt were raised off the floor and sometimes had headrests instead of pillows.
Read 22Pillows were once made from stone, wood and straw in different times and places.
Read 23Mattresses were traditionally stuffed with straw, feathers or horsehair depending on local materials.
Read