Sleep debt tracker

Inputs

Target sleep hours/night	8
Mon (hours)	6.5
Tue (hours)	7
Wed (hours)	6
Thu (hours)	6.5
Fri (hours)	7.5
Sat (hours)	9
Sun (hours)	8
Recovery nightly bonus	1

Supporting metrics

Weekly total slept	50.5
Weekly target	56.0
Average nightly	7.21
Nights at recovery rate to repay debt	5.5

About this calculator

Sleep debt — the metric that actually predicts performance

Sleep debt is cumulative hours short of your target across a rolling window. Unlike "hours slept last night," sleep debt tracks the carryover that determines next-day cognition, mood, and recovery.

Real-world impact of sleep debt

2 hours below target one night: ~10% drop in reaction time the next day. Equivalent to ~0.05% blood alcohol.
6 hours nightly for a week (when you need 8): -25% executive function, immune suppression, glucose tolerance reduction comparable to pre-diabetes.
>4 hours weekly debt: athletes show ~5% drop in max strength and 10% drop in time-to-exhaustion.

How to repay sleep debt

You can repay debt, but slowly:

+1 hour/night for the count of debt-hours you owe is the realistic max
Sleeping 12 hours one night doesn't undo a week of 6-hour nights
Weekend "catch-up" is real but partial — studies show full recovery takes 3-4 nights at +1 hour, not one big night

Caveats

The 8-hour target is the median; individual range is 7-9 hours. Some genuine "short sleepers" function at 6 (rare, genetic — DEC2 mutation). Most people who think they only need 6 are actually running with chronic debt and don't notice the impairment.

Track your sleep for 14 days and find your best-feeling 7-day average. That's your real target.

FAQ

Can I 'bank' sleep before a busy week?

Slightly. Studies show extending sleep by 1-2 hours/night for a week before sleep restriction reduces the impairment. But you can't bank weeks ahead — the surplus diminishes over 3-4 days.

Naps — do they count?

Yes, partial credit. A 20-minute power nap is genuinely restorative without REM rebound. A 90-minute nap completes a full cycle and counts roughly 1:1 against debt. 30-60 minute naps are the worst — they hit you in slow-wave sleep and cause grogginess (sleep inertia).

Why does Saturday-Sunday catch-up fail?

Because circadian rhythm matters as much as duration. Sleeping 11pm-9am Saturday vs 11pm-7am weekdays creates 'social jetlag' — your body clock shifts, and Monday's wake-up feels like a transatlantic flight. Better strategy: consistent bedtime, slight wake-time flexibility, plus a Saturday afternoon nap.

Wearable sleep tracking — accurate?

Total sleep time: ±10% accurate on most consumer wearables. Sleep stages (REM/deep/light): much less accurate, often guessing within 30-40% of polysomnography truth. Use the total hours, ignore the stage breakdowns unless you have a research-grade device.