😴 Sleep Calculator

Each sleep cycle = approximately 90 minutes Optimal sleep = 5–6 complete cycles If wake time is 6:30 AM and latency is 14 min: Actual sleep start = 6:30 AM − 14 min = effective sleep onset reference point Working backwards in 90-min increments: 6 cycles: 6:30 − (6×90 min) − 14 min = 11:16 PM bedtime 5 cycles: 6:30 − (5×90 min) − 14 min = 12:46 AM bedtime 4 cycles: 6:30 − (4×90 min) − 14 min = 2:16 AM bedtime

Newborns (0–3 mo): 14–17 hours/day Infants (4–11 mo): 12–15 hours/day Toddlers (1–2 yrs): 11–14 hours/day Preschool (3–5 yrs): 10–13 hours/day School age (6–13 yrs): 9–11 hours/day Teens (14–17 yrs): 8–10 hours/day Adults (18–64 yrs): 7–9 hours/day Older adults (65+): 7–8 hours/day

Sleep Debt = Sum of nightly deficit over time Daily deficit = Target sleep − Actual sleep Example (8-hr target): Mon: slept 6h → deficit 2h Tue: slept 7h → deficit 1h Wed: slept 5h → deficit 3h Weekly sleep debt = 6 hours Recovery: +1-2 extra hours per night on weekends Full recovery from major sleep debt takes 1-3 weeks. Cannot fully recover large debt in one long sleep.

Consistent schedule: Same bed/wake time every day (even weekends) keeps circadian rhythm stable Temperature: 16–19°C (61–67°F) optimal Body temp must drop for sleep onset Light: Block blue light 1-2hr before bed Bright light in morning anchors circadian clock Caffeine cutoff: 14:00 (2 PM) for most people Half-life: 5–6 hours Alcohol: Disrupts REM sleep — avoid near bedtime Screen-free wind-down: 30-60 min before bed Exercise: Finish 3-4 hrs before sleep (boosts SWS)