The recommended amount of core sleep for adults is typically about 2.5 to 4 hours per night, which corresponds to 35–45% of a full night's sleep. Core sleep includes both deep sleep (NREM stage 3) and REM sleep. Adults usually need 7 to 9 hours of total sleep, with core sleep being the most restorative part of the cycle. The exact amount varies depending on age, health, and lifestyle factors. Core sleep typically includes:
- Deep sleep: about 20-25% of total sleep (1.5 to 2 hours)
- REM sleep: about 20-25% of total sleep (1.5 to 2 hours)
Together, this means 3 to 4 hours of core sleep (deep + REM) is ideal for most adults to support physical recovery, cognitive function, emotional regulation, and overall health. Less than this may lead to reduced mental clarity, greater stress, and health risks over time.
