Protect 7–9 h of sleep
AStrong evidenceThe single largest, most reliable lever on next-day attention and working memory. Nothing in a bottle beats it.
Grade A — Strong evidence
What it does
Sleep consolidates memory and clears metabolic waste. Even partial restriction degrades sustained attention and working memory measurably within days.
How to take it
Anchor a fixed wake time. Aim for 7–9 h. Last caffeine 8–10 h before bed; dark, cool room.
Caveats & safety
Chronic insomnia needs CBT-I, not just hygiene tips. Persistent issues warrant a clinician.
The evidence
Lim J, Dinges DF. A meta-analysis of the impact of short-term sleep deprivation on cognitive variables. Psychol Bull.
2010 · Meta-analysis, 70 studies
Sleep deprivation impairs lapses of attention most, then working memory and processing speed.
Effect: Largest effect on simple attention (Hedges' g ≈ 0.7+); robust across studies.
Read on PubMed →Should this be in your routine?
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