REM stages and one REM stage. Ideally, you repeatedly cycle through each stage. Learn how long each stage lasts.

It’s typically classified as its own category compared to NREM sleep (aka non-REM sleep), the latter of which has three stages that include light sleep and deep sleep. During REM sleep ...

On an Apple Watch, "core sleep" is another name for light sleep, which scientists also call stages N1-N2. It is not a type of ...

Hallucinogens like DMT, psilocin, and LSD might rewrite the rules of sleep, blurring the line between dreams and reality.

Overall, REM sleep occupies about one-fifth of total rest time in adults. Yet stages 1 through 4 have been labeled as non-REM sleep, or NREM—80 percent of sleep is defined by what it’s not.

From stage three, you move into REM (or “rapid eye movement”) sleep, before rising up through the non-REM stages again. Then, ...

For the next in our series of conditions GPs might rarely encounter, Neurology consultant Dr Clare Bolton provides an ...

Deep sleep is the restorative stage of sleep. During this stage the body undergoes tissue repair, the immune system is ...

Night terrors aren't uncommon, but they are really difficult for adults to see. When my son had sleep terrors, I had to change how I parented during the day.

A study on birds finds that when jackdaws are sleep-deprived, they stop sleeping with one eye open and enter deeper sleep, risking safety.