Nightly sleep for recovery, hormones and release.
A multi-disciplinary expert panel reviewed hundreds of studies on sleep and health, and concluded healthy adults need 7–9 hours per night. Chronically sleeping less is associated with worse recovery, hormones, and cardiometabolic risk.
What the researchers did
The National Sleep Foundation convened 18 specialists across sleep, medicine and physiology to systematically review the literature and issue age-banded sleep-duration recommendations. The methodology was published so other groups could reproduce it.
The key finding
For adults 18–64, 7–9 hours per night was optimal. Under 6 hours was flagged as 'not recommended' — it associates with impaired glucose tolerance, higher , lower , worse and blunted training adaptations.
Why it matters
Sleep is the single cheapest and most powerful recovery tool. A week of restricted sleep drops in healthy young men by around 10–15% (Leproult 2011) and worsens insulin sensitivity within days.
Protect a 7.5–8 hour sleep window like you protect a training session. Consistent wake times matter as much as total hours.
- 1.6–2.2Daily protein intake that maximises hypertrophy.
- 8,000Daily step count where all-cause mortality risk levels off — largely a NEAT effect.
- 3–5Creatine monohydrate dose — no loading needed.
- 3–6Pre-training caffeine dose that reliably improves strength and endurance output.
- 25–38Daily fibre intake linked to lower all-cause mortality and a healthier gut microbiome.
- 10–20Hard working sets per muscle per week for hypertrophy.