## TL;DR

Sleep hygiene encompasses habits promoting consistent, quality sleep. Key practices: consistent sleep/wake times, cool dark quiet room, no screens 1hr before bed, avoid caffeine after 2pm, exercise during day, wind-down routine. Poor sleep hygiene = poor sleep = poor health. Adults: 7-9 hours.

## Core Explanation

Blue light: suppresses melatonin. 20-3-8 rule: no caffeine after 2pm, no alcohol within 3 hours of bed, no exercise within 8 hours. Bedroom temperature: 18-20°C (65-68°F) optimal. Consistency: same wake time daily (even weekends) — more important than same bedtime. Jet lag cure: adjust to destination time immediately, sunlight exposure.

## Further Reading

- [Why We Sleep (Matthew Walker)](https://www.simonandschuster.com/books/Why-We-Sleep/Matthew-Walker/9781501144325)