Sleep phases

When you sleep at night, your body cycles between NREM and REM sleep. Find out what happens in the different stages of sleep.

Delayed sleep phase syndrome (DSPS) is a circadian rhythm sleep disorder that affects sleep-wake times and commonly occurs with ADHD. Learn the signs and appropriate treatments for this condition.

Dreaming, memory-making, problem-solving: A lot happens during the most active sleep phase

Circadian Rhythm Sleep Disorders are a group of sleep disorders that affect the timing of sleep, characterised by an inability to sleep and/or wake at normal or appropriate times due to the dictates of the individual’s biological or circadian clock. Learn more

Use our sleep calculator to find your best bedtime based on age and your desired wake-up time.

In 1953, Dr. Dement helped classify the five stages of sleep by distinguishing REM sleep. Here, learn from him and his Stanford students about the two types of sleep and their 5 stages.

Sleep paralysis hallucinations happen during REM sleep. People see, hear, or feel things that aren’t there. Learn how to prevent sleep paralysis.

While mice sleep, their brain cells shrink, allowing cerebrospinal fluid to flow easily around them. The fluid can then clear away toxins. This finding appears to offer the best explanation yet of why animals and people need sleep.

our baby may have your eyes or your lips, but when it comes to sleep, the two of you are quite dissimilar. Sleep might seem rather simple to you, but there's a lot more to sleep than simply "awake" and "asleep." Our newborn sleep cycle chart shows the 4 different sleep phases: