Are naps good or bad?

Short naps of 10–25 minutes improve alertness without grogginess. Naps over 45 minutes or after mid-afternoon can reduce nighttime sleep drive. If you have insomnia, avoid napping altogether while re-establishing your rhythm.

A 10-25 minute nap before 3 pm improves alertness without entering deep sleep, which is what causes post-nap grogginess.

Sudden new need for daily long naps, or falling asleep unintentionally, can indicate sleep apnoea or another disorder and deserves assessment.