Sleep
// What the research shows
A large meta-analysisMeta-analysis A study of studies: the results of many individual studies are pooled statistically. More in the glossary → (Craven et al., 2022) shows that acute sleep loss lowers performance across almost all domains, but only slightly for strength and most for skill-based tasks. A systematic reviewSystematic review A review that searches for and evaluates all relevant studies on a question using fixed, predefined rules. More in the glossary → (Knowles et al., 2018) found that one night without sleep had little effect on muscle strength, while several consecutive nights of restricted sleep reduced force in multi-joint movements.
// In practice
- One bad night is no reason to skip training. Go a bit lighter if needed.
- Chronic short sleep is the real problem, not the occasional bad night.
- After poor sleep, training with others, caffeine or a nap beforehand can help.
// Limitations & open questions
Almost all studies measure acute performance, not long-term muscle gain. How much chronically short sleep slows progress over months is barely studied.
// Sources
- Meta-Analyse 2022Craven et al. – Effects of acute sleep loss on physical performance (Sports Medicine) ↗
- Systematic Review 2018Knowles et al. – Inadequate sleep and muscle strength: implications for resistance training (J Sci Med Sport) ↗
// More from Recovery
Combining cardio & strength training
Cardio doesn't kill gains. Hypertrophy and maximal strength aren't impaired on average, only explosive strength a little.
Stretching before training
Short static stretches (under 60 seconds per muscle) barely hurt. Long holds right before training cost strength.
Ice baths after training
Regular ice baths right after lifting probably blunt muscle growth.
Training breaks & muscle loss
One to four weeks off barely costs maximal strength. Longer breaks slowly cost muscle.