Disclaimer

Last updated: September 2026. Please read this page carefully before using our calculators.

Educational information only

All content on SleepCycle — calculators, articles, tables, and examples — is published for general educational purposes. It is not sleep advice and is not a substitute for a qualified professional. We are not physician or sleep specialists, and no client or advisory relationship is created by your use of this Site.

Sleep-cycle mathematics describe averages — individual cycles run 80–120 minutes and vary nightly. Persistent insomnia, loud snoring with daytime sleepiness, unrefreshing sleep despite adequate hours, or falling asleep while driving are medical symptoms, not calculator problems: they deserve a physician or accredited sleep clinic.

Caffeine sensitivity varies with genetics, medications, pregnancy, and liver health. The curfew model uses a standard half-life; adjust to your own experience.

Accuracy of calculations

We implement well-known, publicly documented formulas (see the methodology section on each calculator page and published sleep-medicine research (AASM, NSF guidance) as applicable). Even correctly implemented formulas produce estimates that depend on your inputs and assumptions. Real-world outcomes vary. Do not rely on a single web tool for a consequential decision.

Advertising disclosure

SleepCycle is funded by display advertising served through Google AdSense. Advertisers have no influence over our content, formulas, or editorial choices, and placement of an ad is not an endorsement.

Errors and corrections

If you spot an error, please email contact@nftycalcs.com with the inputs you used. Verified corrections are published promptly.