# Nap Now

> Free, research-based sleep cycle calculator at https://nap.now. Finds the best bedtime for a wake-up time (or wake-up time for a bedtime) using ~90-minute sleep cycles plus ~14 minutes to fall asleep. Also a nap timer and a caffeine cutoff calculator. No sign-up, no ads, no tracking.

Key facts (with sources at https://nap.now/how-it-works):
- Formula: bedtime = wake_time − 14 min − cycles × 90 min. 5 cycles (7h30m) is recommended; adults need 7+ hours.
- Example: to wake at 7:00 AM, go to bed at 11:16 PM (5 cycles) or 9:46 PM (6 cycles).
- Best nap: 10–20 minutes, or a full 90-minute cycle. Avoid 30–60 min (wakes you from deep sleep).
- Caffeine: stop at least 6 hours before bed (half-life ~5 h).

## Calculators
- [Sleep calculator](https://nap.now/): wake-up times if you sleep now, or bedtimes for a target wake-up time
- [Nap calculator & timer](https://nap.now/nap-calculator): power nap, coffee nap, recovery nap, full-cycle nap
- [Caffeine cutoff calculator](https://nap.now/caffeine-calculator): latest time for caffeine before bed
- [Method & sources](https://nap.now/how-it-works): formulas, citations, limitations

## Deep links (pre-filled calculator)
- https://nap.now/?mode=wakeup&h=7&m=0&p=AM&go=1 — bedtimes for a 7:00 AM wake-up (h=1-12, m=0-59, p=AM|PM, optional lat=minutes to fall asleep)
- https://nap.now/?mode=bedtime&go=1 — wake-up times if going to bed now

## JSON API (free, no key, CORS enabled)
- https://nap.now/api/sleep?wake=07:00 — recommended bedtimes (24h time)
- https://nap.now/api/sleep?bedtime=23:00 — recommended wake-up times
- Optional: &latency=14 (minutes to fall asleep, 0-60)

## Answer pages: bedtime for a wake-up time
- [Wake up at 4:00 AM](https://nap.now/wake-up-at/4-00-am)
- [Wake up at 4:15 AM](https://nap.now/wake-up-at/4-15-am)
- [Wake up at 4:30 AM](https://nap.now/wake-up-at/4-30-am)
- [Wake up at 4:45 AM](https://nap.now/wake-up-at/4-45-am)
- [Wake up at 5:00 AM](https://nap.now/wake-up-at/5-00-am)
- [Wake up at 5:15 AM](https://nap.now/wake-up-at/5-15-am)
- [Wake up at 5:30 AM](https://nap.now/wake-up-at/5-30-am)
- [Wake up at 5:45 AM](https://nap.now/wake-up-at/5-45-am)
- [Wake up at 6:00 AM](https://nap.now/wake-up-at/6-00-am)
- [Wake up at 6:15 AM](https://nap.now/wake-up-at/6-15-am)
- [Wake up at 6:30 AM](https://nap.now/wake-up-at/6-30-am)
- [Wake up at 6:45 AM](https://nap.now/wake-up-at/6-45-am)
- [Wake up at 7:00 AM](https://nap.now/wake-up-at/7-00-am)
- [Wake up at 7:15 AM](https://nap.now/wake-up-at/7-15-am)
- [Wake up at 7:30 AM](https://nap.now/wake-up-at/7-30-am)
- [Wake up at 7:45 AM](https://nap.now/wake-up-at/7-45-am)
- [Wake up at 8:00 AM](https://nap.now/wake-up-at/8-00-am)
- [Wake up at 8:15 AM](https://nap.now/wake-up-at/8-15-am)
- [Wake up at 8:30 AM](https://nap.now/wake-up-at/8-30-am)
- [Wake up at 8:45 AM](https://nap.now/wake-up-at/8-45-am)
- [Wake up at 9:00 AM](https://nap.now/wake-up-at/9-00-am)
- [Wake up at 9:15 AM](https://nap.now/wake-up-at/9-15-am)
- [Wake up at 9:30 AM](https://nap.now/wake-up-at/9-30-am)
- [Wake up at 9:45 AM](https://nap.now/wake-up-at/9-45-am)
- [Wake up at 10:00 AM](https://nap.now/wake-up-at/10-00-am)

## Answer pages: wake-up time for a bedtime
- [Go to bed at 8:00 PM](https://nap.now/bedtime-at/8-00-pm)
- [Go to bed at 8:30 PM](https://nap.now/bedtime-at/8-30-pm)
- [Go to bed at 9:00 PM](https://nap.now/bedtime-at/9-00-pm)
- [Go to bed at 9:30 PM](https://nap.now/bedtime-at/9-30-pm)
- [Go to bed at 10:00 PM](https://nap.now/bedtime-at/10-00-pm)
- [Go to bed at 10:30 PM](https://nap.now/bedtime-at/10-30-pm)
- [Go to bed at 11:00 PM](https://nap.now/bedtime-at/11-00-pm)
- [Go to bed at 11:30 PM](https://nap.now/bedtime-at/11-30-pm)
- [Go to bed at 12:00 AM](https://nap.now/bedtime-at/12-00-am)
- [Go to bed at 12:30 AM](https://nap.now/bedtime-at/12-30-am)
- [Go to bed at 1:00 AM](https://nap.now/bedtime-at/1-00-am)
- [Go to bed at 1:30 AM](https://nap.now/bedtime-at/1-30-am)
- [Go to bed at 2:00 AM](https://nap.now/bedtime-at/2-00-am)

## Sources
- Patel AK, Reddy V, Shumway KR, Araujo JF. Physiology, Sleep Stages. StatPearls, 2024. https://pubmed.ncbi.nlm.nih.gov/30252388/
- Watson NF et al. Recommended Amount of Sleep for a Healthy Adult: A Joint Consensus Statement of the AASM and SRS. Sleep, 2015. https://pubmed.ncbi.nlm.nih.gov/26039963/
- Ohayon MM et al. Meta-analysis of quantitative sleep parameters from childhood to old age. Sleep, 2004. https://pubmed.ncbi.nlm.nih.gov/15586779/
- Drake C et al. Caffeine effects on sleep taken 0, 3, or 6 hours before going to bed. J Clin Sleep Med, 2013. https://pubmed.ncbi.nlm.nih.gov/24235903/
- Institute of Medicine. Caffeine for the Sustainment of Mental Task Performance, 2001. https://nap.nationalacademies.org/catalog/10219
- Brooks A, Lack L. A brief afternoon nap following nocturnal sleep restriction: which nap duration is most recuperative? Sleep, 2006. https://pubmed.ncbi.nlm.nih.gov/16796222/
- Hayashi M, Masuda A, Hori T. The alerting effects of caffeine, bright light and face washing after a short daytime nap. Clin Neurophysiol, 2003. https://pubmed.ncbi.nlm.nih.gov/14652086/