When sleep is good, you wake feeling rested and refreshed. But to get there, you must experience each of the sleep stages. The stages of sleep can be broken down into two categories: REM (rapid eye movement) and NREM (non-rapid eye movement).
NREM sleep makes up about 75% of your total sleep time, and consists of progressively deeper stages of sleep.
- N1 (Stage 1) – The lightest stage of sleep, when you are between being awake and asleep.
- N2 (Stage 2) – When you fall more soundly asleep, and become unaware of your surroundings.
- N3 (Stages 3 and 4) – Stages of deep, restorative sleep believed to be important to your health. Brain activity occurs in slow waves during this stage and you can be difficult to awaken.
- This stage of sleep is characterized by an active brain and is when dreams occur. Lasting about 10 minutes, this typically happens 90 minutes after you fall asleep and every 90 minutes thereafter. Your eyes move but your body is still relaxed.
- A night of sleep generally begins with long periods of deep sleep with shorter REM periods. Closer to morning, REM sleep increases as deep sleep stages decrease.
- This cycle of NREM sleep to REM sleep continues throughout the night, working together to refresh and restore your body while you rest. A good night’s sleep revitalizes and restores your body. It brightens your mood, boosts creativity, regulates hormones, and protects against illness. For optimal health, most adults should try to get 7 to 9 hours of sleep per night.