Restorative sleep

Restorative sleep is sleep of sufficient length and quality that a person wakes feeling refreshed and able to function well during the day.

The term is not a formal diagnosis but a way of describing sleep that does its job. Physiologically, it depends on cycling through light sleep, deep slow-wave sleep and REM sleep without excessive fragmentation, and on getting enough total sleep for one's age, typically seven to nine hours for adults. Deep sleep is associated with physical recovery and immune function, while REM is tied to memory and emotional processing.

The opposite, non-restorative sleep, is a common complaint in insomnia, sleep apnea, fibromyalgia and depression, and it is assessed through sleep diaries, questionnaires about daytime function and, when needed, an overnight sleep study. Cannabinoids have been studied for sleep in small trials, with inconsistent effects on objective and subjective sleep measures.