Question 1

What is sleep debt?

Accepted Answer

Sleep debt is the cumulative difference between the sleep you need and the sleep you actually get. If you need 8 hours but sleep 6, you accumulate 2 hours of sleep debt. This debt affects cognitive performance, mood, immune function, and metabolic health. It cannot be fully repaid in a single night.

Question 2

Can you catch up on sleep?

Accepted Answer

Partially. You can recover some sleep debt with extra sleep over subsequent nights, but research shows that full cognitive recovery from extended sleep deprivation takes longer than most people expect. After one week of mild sleep restriction, it takes approximately 3 days of full sleep to restore baseline performance. Some effects, particularly on metabolism, may persist longer.

Question 3

How much sleep do adults need?

Accepted Answer

The National Sleep Foundation recommends 7–9 hours for adults aged 18–64, and 7–8 hours for those 65+. Individual needs vary — about 1-3% of people genuinely function on 6 hours, but most people who think they're fine on 6 hours are simply adapted to feeling tired.