Nighttime leg cramps usually occur in the calves, feet, and thighs, and last from a few seconds to several minutes. After a cramp, muscle pain may persist. This phenomenon affects both men and women, and occurs more frequently in adults over the age of 50.

It is important to distinguish between nocturnal leg cramps and restless leg syndrome (RLS), as both occur during the night but have distinct characteristics:

Restless legs syndrome (RLS) does not cause cramping or pain, whereas leg cramps do.
RLS is characterized by a crawling sensation in the legs.
RLS forces leg movement, while leg cramps impede movement.
Moving the leg can relieve the discomfort of restless legs syndrome, but it will not help during a cramp.
The exact cause of leg cramps is often unknown, but possible triggers and risk factors include: