Sleep and memory

• Deep sleep sorts the day. During deep, slow-wave sleep, richest in the first half of the night, the brain replays what you learned during the day and helps move it into long-term memory (Rasch and Born, 2013).
• REM sleep plays a different part. Dream sleep seems to matter more for skills and for emotional memories, and it may help stabilise what deep sleep has reorganised (Rasch and Born, 2013).
• Sleep before learning counts too. A tired brain takes in new information less well. A good night protects what you learned yesterday and prepares what you will learn tomorrow (Rasch and Born, 2013).

Adults aged 18 to 60 should sleep seven hours or more a night, according to the American Academy of Sleep Medicine and the Sleep Research Society (Watson and colleagues, 2015).

1. Study, then sleep. An all-night session takes away the very sleep that would keep what you studied.
2. Keep regular hours, and keep the phone off and out of the bedroom.
3. Test yourself the next morning. It adds retrieval practice, the technique with the strongest evidence, to the work sleep has already done. Retrieval and spacing
4. After a short night, a nap can help.

If you sleep badly for weeks, or wake up tired after a full night, talk to a doctor. This page is about memory, not about sleep disorders.