🔬 Built by a Sleep Scientist in Boulder

I Woke Up Tired for 10 Years. Then I Learned About 90-Minute Cycles.

Free sleep calculators that run entirely in your browser. No sign-ups. No data collection. Just the math your alarm clock never told you.

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The Night Everything Changed

It was 3:47 AM. I was holding my son, rocking him back to sleep, and staring at my own reflection in the dark window. I had a PhD in Behavioral Neuroscience. I had spent six years in a sleep lab at CU Boulder. And I had not slept through the night in fourteen months.

The next morning, I pulled out my old lab notebooks. I found the data we had collected on ultradian rhythms — the 90-minute cycles that govern not just sleep, but alertness, creativity, and mood. I realized I had been setting my alarm at the wrong point in my cycle for a decade.

That is when I built the first version of the Sleep Cycle Calculator. For myself. Then my husband started using it. Then my mom. Then my mom's book club. Now it is here for you.

Read the full story →

The Tools I Use Every Night

Six calculators. Every piece of data stays in your browser — we never see it, store it, or sell it.

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Sleep Cycle Calculator

Enter your target wake-up time. Get five optimal bedtimes based on 90-minute cycles. No more waking up in the middle of deep sleep.

Most Popular
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Bedtime Finder

Tell us when you usually sleep and how you feel. We will recommend a bedtime shift with a realistic adjustment plan.

Planning
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Nap Planner

Calculate the perfect nap length and timing. Avoid sleep inertia with our 10-minute vs. 90-minute nap guide.

Quick Fix
View All 6 Tools

All Sleep Tools

Every calculator uses peer-reviewed sleep science. No pseudoscience. No miracle cures.

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Sleep Cycle Calculator

Calculate optimal bedtimes using 90-minute cycle theory. Supports custom cycle lengths.
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Bedtime Finder

Find your ideal bedtime based on current habits and desired wake time.
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Nap Planner

Plan naps that boost energy without causing grogginess. Timing is everything.
📊

Sleep Debt Tracker

Log your sleep and see your accumulated debt. Get a realistic repayment plan.
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Sleep Quality Score

10-question assessment covering sleep latency, efficiency, and daytime function.
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Jet Lag Adjustor

Plan your gradual schedule shift before cross-timezone travel. Export to calendar.
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From the Sleep Lab Diaries

Real experiments, real data, real mistakes. No sleep industry BS.

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Your Sleep Journey

Step 1: Calculate Your Cycle

Use the Sleep Cycle Calculator to find your optimal bedtime based on your wake-up time.

Step 2: Track for 7 Days

Log your actual sleep times in the Bedtime Finder. See how reality compares to theory.

Step 3: Adjust Gradually

Shift your bedtime by 15 minutes every 3 days. Your circadian rhythm needs time to adapt.

Step 4: Wake Up Without an Alarm

Most people need 3-4 weeks. When you hit the right cycle, you will wake up before the alarm goes off.

Common Questions

Is my sleep data really private? +

Yes. All calculations happen in your browser. We do not have a database. We cannot see your bedtime, your sleep debt, or anything else you enter.

How accurate is the 90-minute cycle? +

It is an average. Individual cycles range from 80 to 120 minutes. Our calculator shows you a range of optimal bedtimes, not just one.

Can I use these tools if I have insomnia? +

Our tools help you understand patterns, but they are not a treatment. If you have chronic insomnia, please see a sleep specialist or CBT-I therapist.

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