😴 Sleep Hygiene Habit Modification Simulator

Circadian Anchoring Through a Fixed Sleep-Wake Schedule

A regular bedtime and wake time stabilizes the internal clock.

• ±15 min: Schedule variance (target consistency window)
• Low: Circadian shift risk (when schedule is fixed)
• Wake time: Recommended anchor (more stable than bedtime)
• ~2 weeks: Adaptation window (to entrain new schedule)

Why schedule regularity matters

A stable schedule reduces sleep onset variability.

Caffeine Timing and Its Five-Hour Half-Life Curve

Afternoon caffeine lingers into the evening and delays sleep.

• ~5 hrs: Caffeine half-life (average adult metabolism)
• 2pm: Cutoff recommendation (for a ~10pm bedtime)
• Yes: Adenosine blockade (mechanism of alertness)
• >200mg: Sensitive dose (noticeable latency increase)

Adenosine receptor blockade

Caffeine blocks sleep-pressure signaling in the brain.

Blue Light Exposure and Melatonin Suppression Before Bed

Screens emit blue-enriched light that delays melatonin onset.

• ~460-480nm: Peak suppression light (blue wavelength band)
• ~40-50%: Suppression at 60min (typical screen exposure)
• 60 min: Recommended cutoff (before bedtime)
• Dim/warm light: Mitigation (reduces suppression)

Melatonin suppression mechanism

Blue light signals daytime to the suprachiasmatic nucleus.

Thermal Optimization of the Sleep Environment

Cooler bedrooms help core body temperature drop for sleep.

• 16-19°C: Optimal range (ideal bedroom temperature)
• ~1°C: Core temp drop (needed to initiate sleep)
• +latency: Too warm effect (delays sleep onset)
• Fragmentation: Too cold effect (more night wakings)

Thermoregulation and sleep onset

A cooling room mimics the natural nighttime temperature dip.

Compounding Effects of Combined Sleep Hygiene Habits

Together, these habits produce the largest quality gains.

• Up to -50%: Combined latency gain (vs. single-habit change)
• +20-30 pts: Quality score gain (full optimization)
• Key driver: Adherence factor (of long-term outcome)
• 1-3 weeks: Time to benefit (consistent practice)

Stacking habit changes

Small consistent changes across habits compound over time.

Placeholder: combined habits outperform any single fix.