REM (rapid eye movement) sleep is important because it supports brain function, emotional balance, and learning. It is one of the key stages your body needs to feel mentally refreshed and stable the next day.
Brain and memory
During REM sleep, the brain is highly active and helps consolidate memories, especially those related to learning new information and skills. This stage strengthens connections between brain cells, which supports concentration, problem-solving, and overall cognitive performance.
Emotions and mental health
REM sleep plays a major role in processing emotions and emotional memories from the day. Getting enough REM sleep is linked to better mood regulation and lower risk of issues like irritability, anxiety, and depression.
Physical health and restoration
Although deep non-REM sleep is most critical for physical repair, REM sleep contributes to overall sleep quality and helps the brain “clean up” waste products that can build up during waking hours. Poor or reduced REM sleep over time is associated with weaker immune function and higher risk of chronic conditions such as heart disease and diabetes.
What happens if you lack REM
Too little REM sleep can lead to problems with attention, memory, and daytime alertness, even if total sleep time seems adequate. Chronic REM sleep loss is also tied to greater daytime sleepiness, mood problems, and reduced mental and physical performance.
How much REM you need
In a typical night, REM cycles repeat several times and usually make up about 1.5–2.5 hours of an adult’s sleep, increasing in length toward the morning. Ensuring enough total sleep and a consistent schedule helps the body naturally reach and maintain healthy amounts of REM sleep.
