About BedtimeCalc

The Sleep Calculator Trusted by 2.8 Million People

We built BedtimeSleepCalculator.com because sleep science is clear and the tools to apply it were not freely available. That changes when you understand 90-minute cycles.

2.8M+Users Helped

190+Countries

820+Sleep Guides

4.9★User Rating

Our Mission

Sleep deprivation is a global public health crisis. The WHO classifies insufficient sleep as an epidemic in industrialised nations. Yet the science of sleep timing is straightforward, evidence-backed, and almost completely unknown to the public. BedtimeSleepCalculator.com exists to change that. We translate peer-reviewed research into free, actionable tools anyone can use in 30 seconds.

The Science

Our calculator is grounded in the 1953 discovery by Nathaniel Kleitman and Eugene Aserinsky at the University of Chicago. They established that sleep progresses through 90-minute cycles of NREM and REM stages. Waking at the end of a complete cycle produces dramatically less grogginess than waking mid-cycle. Our calculator finds your cycle-aligned bedtime for any alarm time.

Evidence standard: Every recommendation is grounded in peer-reviewed research. We cite specific studies with author names, institutions, and publication years. We never make health claims that exceed what the evidence supports.

Meet the Team

🌙

Dr. Sarah Chen

Sleep Science Lead

PhD in Chronobiology, University of Oxford. 12 years researching circadian rhythms and sleep architecture.

📊

Marcus Williams

Data and Engineering

Former Google engineer. Built the calculator algorithms and programmatic content systems.

✍️

Aisha Patel

Content and Research

MSc Health Psychology. Translates complex sleep research into practical, readable guides.

🎨

James Park

Design and UX

Obsessed with making health tools genuinely usable. Previously at Calm and Headspace.

Research Sources

Kleitman and Aserinsky (1953) — Discovery of REM sleep and the 90-minute sleep cycle
Van Dongen, Maislin, Mullington and Dinges (2003) — Cumulative neurobehavioural effects of sleep restriction
Walker (2017) — Why We Sleep: Unlocking the Power of Sleep and Dreams
National Sleep Foundation (2022) — Updated sleep duration recommendations for all age groups

Editorial Independence

We earn revenue through affiliate commissions on products in our sleep shop. These recommendations are chosen based on sleep science evidence, not payment. We do not accept sponsored content or paid placements that influence editorial recommendations.