Enter your wake-up time. Instantly see if you'll get enough sleep tonight.
| Sleep rating | — |
| vs. recommended minimum | — |
| Deep sleep window | — |
No apps. No accounts. Just answers.
"Can I sleep now?" "How long should I nap?"
One or two inputs. Bedtime, wake-up time, nap length — that's it.
Duration, cycles, rating, and a short tip.
Pick the one that fits your question.
Enter bedtime and wake time. Get actual sleep length, cycle count, and a data-backed rating.
Most UsedHow long until you wake up? See cycles at a glance.
Reverse-engineer your ideal bedtime from 90-min cycles.
PopularPick a nap length and see the best wake time.
Recommended daily sleep by age.
Crossing time zones? Estimate adjustment days.
Track deficit from consecutive short nights.
When your last coffee clears your system.
Evidence-based guides, tool walkthroughs, and the science behind better rest.
Blackout curtains can transform your sleep. Here's how to pick the right ones, plus what I learned after testing five pairs.
Your bedroom thermostat might be ruining your sleep. Here's the science-backed sweet spot and simple ways to reach it without fighting your partner.
Struggling to fall asleep fast? Learn simple, science-backed tricks to shorten the time it takes to drift off, plus a few honest confessions.
You slept 8 hours but still feel exhausted. Here are the real reasons, from sleep cycles to caffeine timing, and what to do about it.
Coffee keeps you alert for hours, but the real story is caffeine's half-life. Learn how timing your last cup affects your sleep.
Wondering if weekend lie-ins actually fix your sleep debt? Here's what the research shows, plus practical tips for using a sleep calculator to plan your recovery.