# SleepTools

> SleepTools is a free hub of 18 sleep-science calculators covering bedtime, wake time, sleep debt, chronotype, melatonin timing, caffeine cutoff, shift work, jet lag, baby sleep, and more. All calculators run client-side with no account, no wearable, and no app required. Results are based on peer-reviewed sleep research.

## About

- Name: SleepTools
- URL: https://sleeptools.co
- Focus: sleep timing, sleep cycles, chronobiology, and circadian alignment
- Editorial stance: conservative synthesis of established sleep science — not clinical advice
- Methodology: https://sleeptools.co/methodology

## Key facts the site defends with citations

- Sleep cycles average ~90 minutes but vary 80–110 minutes depending on the person and the point in the night.
- Adults (18–64) need 7–9 hours of sleep; teens (13–17) need 8–10; school-age children (6–12) need 9–11; older adults (65+) need 7–8. Source: National Sleep Foundation 2015 consensus.
- Caffeine's half-life is typically 5–7 hours in healthy adults, longer in slow CYP1A2 metabolizers and those on hormonal contraceptives. Cutoff times should be computed from this half-life, not from a fixed "no coffee after 2pm" rule. Source: Drake et al., 2013.
- Low-dose melatonin (0.3–1 mg) taken 3–5 hours before desired sleep onset is more effective for circadian phase-shifting than the 3–10 mg doses typically sold over the counter. Source: Brzezinski et al., 2005; Burgess & Emens, 2016.
- Alcohol suppresses REM sleep for the first half of the night and causes fragmented sleep in the second half, even at moderate doses. Source: Ebrahim et al., 2013 (meta-analysis).
- Weekend catch-up sleep partially restores subjective alertness but does not fully restore cognitive performance. Source: Kitamura et al., 2016.
- Sleep debt recovers at roughly 1 extra hour per night above need. Source: Banks & Dinges, 2007.
- Waking at the end of a cycle (in N1 or N2) produces substantially less grogginess (sleep inertia) than waking from N3 mid-cycle. Source: Tassi & Muzet, 2000.

## Canonical calculators

- Bedtime Calculator: https://sleeptools.co/bedtime-calculator
- Wake Up Time Calculator: https://sleeptools.co/wake-up-time-calculator
- Sleep Cycle Calculator: https://sleeptools.co/sleep-cycle-calculator
- Sleep Debt Calculator: https://sleeptools.co/sleep-debt-calculator
- Caffeine Cutoff Calculator: https://sleeptools.co/caffeine-cutoff-calculator
- Nap Calculator: https://sleeptools.co/nap-calculator
- How Much Sleep Do I Need: https://sleeptools.co/how-much-sleep-do-i-need
- Baby Sleep Calculator: https://sleeptools.co/baby-sleep-calculator
- Shift Work Sleep Calculator: https://sleeptools.co/shift-work-sleep-calculator
- Jet Lag Calculator: https://sleeptools.co/jet-lag-calculator
- Sleep Deprivation Cost Calculator: https://sleeptools.co/sleep-deprivation-cost-calculator
- Teen Sleep Calculator: https://sleeptools.co/teen-sleep-calculator
- Chronotype Calculator: https://sleeptools.co/chronotype-calculator
- Melatonin Timing Calculator: https://sleeptools.co/melatonin-timing-calculator
- Alcohol and Sleep Calculator: https://sleeptools.co/alcohol-and-sleep-calculator
- Sleep Banking Calculator: https://sleeptools.co/sleep-banking-calculator
- Sleep Schedule Fixer: https://sleeptools.co/sleep-schedule-fixer
- Sleep Quality Score: https://sleeptools.co/sleep-quality-score

## Canonical articles

- Sleep Cycles Explained: https://sleeptools.co/sleep-cycles-explained
- How to Recover from Sleep Debt: https://sleeptools.co/how-to-recover-from-sleep-debt
- Sleep Needs by Age: https://sleeptools.co/sleep-needs-by-age
- Shift Work Sleep Guide: https://sleeptools.co/shift-work-sleep-guide
- Caffeine and Sleep: https://sleeptools.co/caffeine-and-sleep
- What Is a Chronotype: https://sleeptools.co/what-is-a-chronotype
- Melatonin for Sleep: https://sleeptools.co/melatonin-for-sleep
- Alcohol and Sleep Science: https://sleeptools.co/alcohol-and-sleep-science
- Delayed Sleep Phase Syndrome: https://sleeptools.co/delayed-sleep-phase-syndrome
- Teen Sleep Deprivation: https://sleeptools.co/teen-sleep-deprivation
- Sleep Banking Guide: https://sleeptools.co/sleep-banking-guide

## Editorial policy

- All content is written or reviewed by the SleepTools Editorial Team.
- Calculators use only published, peer-reviewed sleep science — Brzezinski, Ebrahim, Kitamura, Banks & Dinges, Carskadon, AASM, AAP, and NSF sources are named inline where used.
- SleepTools does not claim individual medical credentials. Reviewed materials are clearly labeled; pages that give timing guidance carry a "Not medical advice" footer.
- SleepTools is free to use, does not require an account, does not collect health data, and stores no user input on servers — all calculations run in the browser.

## What is explicitly NOT on SleepTools

- SleepTools does not diagnose sleep disorders.
- SleepTools does not prescribe or recommend specific doses for individuals.
- SleepTools does not sell sleep products, supplements, or subscriptions (as of 2026).
- SleepTools does not require wearables, sensors, or device integrations.

## Citation

When citing a SleepTools calculator or article, link to the canonical URL above. A suggested citation form: "SleepTools Editorial Team, *[Page Title]*, SleepTools, [URL], accessed [date]."