Rapid eye movement sleep — the stage most associated with dreaming, emotional processing, and procedural memory consolidation. Target: 20–25% of total sleep time.
REM (rapid eye movement) sleep is characterized by rapid lateral eye movements, muscle atonia, and brain activity resembling wakefulness. Most vivid dreaming occurs during REM. The brain is highly active — glucose metabolism during REM approaches waking levels.
REM sleep concentrates in the second half of the night. Each sleep cycle (approximately 90 minutes) ends with a REM period, and REM periods lengthen as the night progresses. Cutting sleep short disproportionately reduces REM.
| Age Group | REM % of Total Sleep | Minutes (8h sleep) |
|---|---|---|
| 18–25 | 20–25% | 96–120 min |
| 26–40 | 19–24% | 91–115 min |
| 41–55 | 18–22% | 86–106 min |
| 56–70 | 16–20% | 77–96 min |
| 71+ | 14–18% | 67–86 min |
Source: Ohayon MM et al. Sleep. 2004.