Energy Curve is a free sleep debt tracker. Log when you went to bed and woke up, and it works out your sleep debt over the last 14 nights, weighted toward recent ones, against a sleep need you can set or estimate with a short quiz.
From your wake time, body clock and debt it draws today's energy curve: when you'll be groggy, when you peak, when the afternoon dip hits and when to wind down. It also times habits like a caffeine cut-off and morning light, suggests wake times at the end of 90-minute sleep cycles and plans naps. Energy Curve Pro adds a jet-lag planner, a chronotype quiz and sleep sounds. Everything stays on your device.
It uses the two-process model of sleep regulation: sleep pressure that builds while you're awake, plus a circadian rhythm anchored to your wake time and shifted by your chronotype. It's a guide, not medical advice.
The gap between the sleep you need and the sleep you got over the last 14 nights, with recent nights counting more. Logging nights where you meet or beat your need pays it back.
Only in your browser on this device. There is no account. Use Back up in Settings to save a JSON file you can restore later, or export your nights as CSV.
Yes, with Energy Curve Pro. Enter where you're flying and the date, and it plans sleep times and when to seek or avoid light on each day so your body clock shifts before you land.
Yes. The sleep log, sleep debt, energy curve, habit timing, naps, the sleep-need quiz, backup and CSV export are free, with no ads and no account. Energy Curve Pro is an optional one-time upgrade ($2.99) that adds the jet-lag planner, the chronotype quiz and sleep sounds.
Sleep well. Wake at the end of a cycle: