How does napping affect your nighttime sleep quality?

Napping can both help and hurt nighttime sleep depending on timing and duration. Short naps of 10 to 20 minutes taken before 3 PM generally improve alertness and mood without significantly disrupting nighttime sleep. These brief naps avoid deep sleep stages, so you wake feeling refreshed rather than groggy. Longer naps or those taken late in the afternoon reduce sleep pressure, which is the biological drive that builds throughout the day and helps you fall asleep at night. This can make it harder to fall asleep, reduce total nighttime sleep time, or fragment your sleep. People with insomnia are typically advised to avoid napping altogether, as it further weakens the sleep drive they already struggle to build.