Nocturnal cramps are pains caused by spasms or muscle contractions in the muscles of the leg and foot, which may persist as residual discomfort. They cause the patient to wake up and are relieved with massage, after which it takes a while to fall back asleep. The prevalence increases with age and in certain situations: pregnancy, excessive exercise, electrolyte abnormalities (hypocalcaemia, hypomagnesaemia, etc.) thyroid disorders, neuromuscular disorders, Parkinson’s disease, etc. A biochemical test should be done. Polysomnography is not necessary, but, if made, it shows periods of high-frequency activity of the calf muscles, which coincide with the symptoms.