Why do I feel tired even after a full night sleep?

Feeling tired despite a full night of sleep usually comes down to sleep quality rather than just duration. If you're not reaching deep or REM sleep stages, your body doesn't fully restore itself. Common causes include sleep apnea, where breathing interruptions prevent restorative sleep, often without you knowing it's happening. Other factors include poor sleep hygiene like inconsistent bedtimes, alcohol before bed, or screen exposure. Underlying issues such as anemia, thyroid problems, depression, or dehydration also cause persistent fatigue. Even diet and lack of physical activity play a role. If this is ongoing, it's worth seeing a doctor to rule out sleep disorders or medical conditions, since chronic fatigue is rarely something to just push through.