What Causes Nighttime Hand Swelling?

A variety of medical conditions, including rheumatoid arthritis, tendinitis, allergic reactions and insect bites, could cause the hands to swell during the night, according to WebMD. Swollen hands in the morning also could be the result of a form of edema caused by staying in one position for long periods while sleeping.

Swelling occurs when tissue becomes enlarged or when water or other fluids, such as pus, build up at the site of an infection or other irritation beneath the skin, notes WebMD. Swelling of the hands and fingers could be caused by excess salt, thyroid disease, chronic kidney or liver disease, or as a side effect of drugs used to treat high blood pressure, diabetes or heart disease, according to the National Institutes of Health.

Swelling is common for pregnant women, but swollen hands can be a warning sign for preeclampsia, a condition marked by high blood pressure. If not treated, preeclampsia can lead to serious health issues for the mother and the child, according to Prevention Magazine.

Waking with stiff, swollen hands and fingers is an early symptom of scleroderma, a condition in which the body creates too much collagen, explains the Scleroderma Foundation. Excess protein causes the fingers to swell, stretching the skin and making it difficult to make a fist.