Sources
Our sleep guidance should be traceable. The sources below are selected from public health agencies and professional or clinical references.
National Heart, Lung, and Blood Institute (NHLBI)
How Sleep Works: Sleep Phases and Stages explains NREM and REM sleep and notes that a sleep cycle starts over roughly every 80–100 minutes, with four to six cycles typically occurring per night.
Centers for Disease Control and Prevention (CDC)
About Sleep provides age-based sleep duration guidance, including 7 or more hours for adults ages 18–60 and 8–10 hours for teens ages 13–17.
American Academy of Sleep Medicine / Sleep Research Society
The adult sleep duration consensus statement recommends that adults sleep 7 or more hours per night on a regular basis for optimal health.
Editorial use of sources
Sources support general educational claims. They are not a substitute for individualized medical advice, diagnosis, or treatment. Each article should be read with its date and context because medical evidence and public guidance can change.