Nocturnal leg cramps, commonly known as 'charley horses,' are sudden, painful muscle contractions that primarily affect the calf muscles, often disrupting sleep. According to Dr. Tarun Suri, Professor & Head of Orthopaedics & Ortho Spine Surgery at Amrita Hospital, Faridabad, the leading explanation for these cramps lies in over-excited motor nerves, particularly at the spinal cord level. During sleep, inhibitory signals to muscles quiet down, causing motor neurons to fire repeatedly and muscles to contract involuntarily. The article clarifies that while often blamed, dehydration and low mineral levels like magnesium or potassium are rarely the primary causes for otherwise healthy individuals. Dehydration typically contributes when it disrupts electrolyte balance in specific conditions, such as for those on diuretics or with kidney disease. Instead, factors like muscle tone dropping during sleep, decreased sensory input, and maintaining shortened limb positions for extended periods contribute significantly. Sleeping postures, especially plantar flexion (toes pointed downward), shorten calf muscles, making them prone to cramping. Tight bed sheets can also exacerbate this. Other contributing factors include sedentary lifestyles, muscle fatigue from overexertion, prolonged standing or sitting, and certain medical conditions such as peripheral artery disease, diabetes, kidney disease, thyroid problems, and neurological disorders. Certain medications can also increase the risk. Prevention strategies include regular stretching of calf and hamstring muscles before bedtime, maintaining good hydration, wearing supportive footwear, and avoiding positions that keep muscles shortened. When a cramp occurs, gentle stretching, massaging the affected muscle, and applying heat can provide relief.