Waking up around 2 a.m. is a common issue for many people, and while it’s easy to blame that late-night glass of water, the real reasons are often more complex. Sleep experts explain that what’s truly happening involves how the body manages fluid and temperature during rest.

Gravity causes fluid to pool in the lower body during the day, but when lying down at night, that fluid returns to the bloodstream, increasing kidney activity and sometimes leading to the urge to urinate.

Beyond fluid redistribution, body temperature plays a key role in sleep quality. If your body fails to regulate its core temperature properly during the night, it can lead to shallow sleep and increased sensitivity to even minor bladder signals. Stress and early-morning hormonal changes can also activate the nervous system, waking you up even without a full bladder or noticeable discomfort.