After a long day, many people notice their shoes feel tighter, their ankles look puffy, or their legs seem heavier than usual. Occasional swelling in the legs can happen for harmless reasons, especially after standing or sitting for many hours. But if your legs swell every night, your body may be trying to tell you something important.

Leg swelling, also called edema, happens when fluid builds up in the tissues. Sometimes the cause is simple. Other times, it may be linked to circulation problems, heart conditions, kidney issues, or other medical concerns that should not be ignored.

Common Causes of Nighttime Leg Swelling

One of the most common reasons is poor circulation. When you spend long periods standing or sitting, gravity pulls fluid downward into your lower legs and feet. This is especially common for office workers, drivers, teachers, nurses, and older adults.

Another possible cause is excess salt in the diet. Foods high in sodium can cause the body to retain water, leading to swelling in the ankles and legs by evening.

Pregnancy can also lead to swollen legs because the body naturally holds more fluid, and pressure on blood vessels increases as the baby grows. Mild swelling is often normal during pregnancy, but sudden or severe swelling should always be checked by a doctor.

Some medications may contribute as well. Blood pressure medications, steroids, hormones, and certain diabetes drugs can sometimes cause fluid retention.