Glossary
Sleep Hygiene
Updated February 28, 2026
Sleep hygiene is the set of behaviors and environment choices that make solid sleep more likely.
Core targets
Use these as the baseline protocol each night.
| Factor | Target |
|---|---|
| Schedule | consistent bed and wake times across work and non-work days |
| Light | bright light in the morning, low-intensity warm light at night |
| Caffeine | cut off 6 to 8 hours before bed |
| Alcohol | low dose, earlier in the evening only |
| Late meals | keep heavy meals and high-fat meals away from bedtime |
| Room | dark, quiet, and cool at night, about 60 to 67F |
| Screens | power down about 60 minutes before bed |
Pre-sleep protocol
| Window | Action |
|---|---|
| 2 hours before bed | finish fluids if needed, finish alcohol and last stimulant |
| 60 minutes before bed | dim all bright screens and reduce stimulating content |
| 30 minutes before bed | hydrate lightly, use fixed wind-down ritual, then lights out |
| Wake day gap | avoid sleeping beyond target in the morning |
Environment and rhythm stack
| Setting | Why it helps |
|---|---|
| cooler room | lowers sleep latency and reduces night waking |
| dark room | increases melatonin reliability |
| white-noise or consistent hush level | reduces micro-arousal from external spikes |
| cool shower in late evening | lowers core temperature over the next hour |
| fixed pillow and mattress position | reduces awakenings from discomfort loops |
Dose-response for repeated poor sleep
| Symptom pattern | Adjustment for 3 to 5 nights | Escalation signal |
|---|---|---|
| Difficulty falling asleep only | tighten first 60-minute screen cutoff and reduce evening caffeine by 50% | continued latency over 45 minutes |
| Frequent waking | set caffeine and alcohol hard stop 8 hours before bed and reduce late fluids | more than 2 wake-ups most nights |
| Early waking | shift light exposure earlier and avoid heavy evening sodium | awakening before target by >60 minutes |
| Daytime fatigue despite 7+ hours | move bedtime earlier in 15 to 30 minute increments until stable |
Pair this protocol with sleep tracking and use stress management first when sleep debt persists. If the practical question is how poor sleep changes appetite, fat loss, and lean-mass retention, go next to Sleep and Fat Loss.
Why these thresholds exist
The targets above are grounded in specific physiology. Core body temperature needs to drop roughly 2 to 3°F (1 to 1.5°C) to initiate sleep onset, which is why a room at 60 to 67°F accelerates this process while a warm room delays it. Caffeine has a half-life of 5 to 6 hours in most adults, meaning half the stimulant remains active at the midpoint. At 10 hours, roughly a quarter remains. A 6 to 8 hour cutoff leaves enough clearance for most people, though slow caffeine metabolizers (CYP1A2 gene variant) may need 10 or more hours. Bright morning light within 30 to 60 minutes of waking advances the circadian clock by suppressing melatonin and anchoring the cortisol awakening response, which stabilizes both sleep onset timing and daytime alertness.