One bad night you can recover. A week of 5-hour nights leaves a metabolic crater you can't fully fill in a weekend.
Calculators do the heavy lifting, but knowing what is going on underneath is what saves you money — or stress — later. One bad night you can recover. A week of 5-hour nights leaves a metabolic crater you can't fully fill in a weekend.
1–2 nights of short sleep: mostly recovered with one 9-hour sleep.
5+ nights short: takes 5–7 nights of full sleep to reset; some cognitive markers remain off for weeks.
Chronic sleep loss raises ghrelin, lowers leptin — eat ~300 kcal/day extra without realising it.
Are naps OK? 20-minute power naps yes; 90-min full-cycle naps yes; in between disrupts night sleep.
What about weekend catch-up? Helps partially but doesn't restore everything. Consistency wins.
Run your own numbers before you trust a rule of thumb. Two minutes saves a lot of regret.