Why am I still tired after 8 hours of sleep?

Why am I still tired after 8 hours of sleep? BestDoctorsInTheCity.com February 27, 2026 Sponsored Feeling tired despite 8 hours of sleep can result from poor sleep quality, stress, sleep disorders (like sleep apnea), vitamin deficiencies, dehydration, or underlying medical conditions. Interrupted sleep cycles and excessive screen time before bed can also reduce restorative sleep.