Recovery · Moderate evidence
How Much to Sleep
Adults should sleep 7 to 9 hours per night; sleeping less was associated with more injuries in young athletes.
Expert panel consensus and meta-analysis · 2 sources · 2 min
What the studies show
- 7 to 9 hours is the recommended range for adults.
- Less than 8 hours in adolescent athletes was associated with a higher risk of injury.
- Consistently sleeping too little has a cumulative effect.
How Letz applies it
The Letz sleep target is 7 to 9 hours; below 6 hours, the coach prioritizes recovery over intensity for the day.
Numbers derived from this rule
| Parameter | Range | Weight | Rule |
|---|---|---|---|
| Sleep per night | 7–9 hours | 60% | 7 to 9 hours per night; below 6, fat loss in a calorie deficit is less efficient and training performance suffers.How Much to Sleep · Sleep and Fat Loss · Sleep, recovery, and performance |
Who it applies to
Adults aged 18 to 64; 7 to 8 hours for those over 65.
Limits
Individual needs vary; the association with injury comes from adolescents and does not prove causality.
Sources
- Hirshkowitz et al., Sleep Health, 2015 DOI 10.1016/j.sleh.2014.12.010
- Gao et al., Journal of Pediatric Orthopaedics, 2019 DOI 10.1097/BPO.0000000000001306
More in Recovery
- Sleep, recovery, and performanceSleep interventions may be accompanied by improvements in recovery and certain performance outcomes.
- Sleep and Fat LossSleeping too little during a deficit shifts fat loss toward lean mass loss and increases intake; extending sleep reduced intake by about 270 kcal per day.
- Monitoring recoveryRecovery should be tracked using simple, frequent measures such as perceived exertion, sleep, and mood; heart rate variability works better as a weekly trend than as a single daily figure.
- Training load does not predict individual injuryRecent training load can provide context for workout decisions, but simple load ratios do not support reliable individual injury prediction.