N3 slow-wave sleep percentage across the lifespan. How much deep sleep is normal at each age, based on polysomnography research.
| Age Group | Mean SWS % | Typical Range | Minutes (8h sleep) |
|---|---|---|---|
| 18–25 | 22% | 18–27% | 86–130 min |
| 26–35 | 20% | 16–24% | 77–115 min |
| 36–50 | 16% | 12–20% | 58–96 min |
| 51–64 | 12% | 8–16% | 38–77 min |
| 65–75 | 8% | 4–12% | 19–58 min |
| 75+ | 5% | 2–8% | 10–38 min |
Source: Ohayon MM et al. Sleep. 2004. Carrier J. Neuropsychology of Sleep and Wakefulness. 2001.