For millennia, philosophers have argued over why humans sleep and dream. In his fourth-century-bc treatise On Sleep and Sleeplessness, the philosopher Aristotle argued that sleep is a necessary, ...

Ever wondered why you sometimes have conversations in your sleep? These are the three leading explanations, according to biology. Every night, your brain performs a kind of controlled disappearing act ...

Curious Kids is a series for children of all ages. If you have a question you’d like an expert to answer, send it to ...

A number that sounds like plenty for humans turns out to be the smallest ration of sleep in the entire primate order. Biologists are still working out why. Seven hours sounds like a reasonable, even ...

Sleep is often treated as a casualty of modern life. Artificial lighting, shift work, endless notifications and late-night entertainment are usually blamed for cutting into the hours people spend ...

Humans adapt. We live in trackless deserts, on the tops of mountains, in pestilential jungles, in prisons and hospitals. To survive we sleep, for we need sleep like food. We adapt to sleeping in space ...

Why can people sleep when they feel 'at ease'?You get into bed at night. You have finished your day and your body is tired.

For decades, the answer to “how much sleep does an adult need?” has been simple: eight hours. The idea dates back to the mid-19th century when the notion of eight hours of work, eight for recreation ...