From the Guidelines
Nighttime leg cramps are primarily caused by muscle fatigue, dehydration, and electrolyte imbalances, as well as underlying medical conditions such as restless legs syndrome (RLS) and periodic limb movement disorder (PLMD) 1. These conditions can lead to insomnia, difficulty falling or staying asleep, and daytime dysfunction. According to the American Academy of Sleep Medicine clinical practice guideline, RLS and PLMD can cause significant morbidity, including difficulty falling or staying asleep present in roughly 90% of people with RLS 1. Some key factors that contribute to nighttime leg cramps include:
- Muscle fatigue and dehydration
- Electrolyte imbalances, particularly low levels of potassium, magnesium, and calcium
- Underlying medical conditions such as RLS, PLMD, peripheral artery disease, diabetes, nerve compression, and pregnancy
- Certain medications like diuretics, statins, and beta-blockers
- Prolonged sitting, improper positioning of the legs while sleeping, overexertion during exercise, or standing on hard surfaces for extended periods To prevent nighttime leg cramps, it is essential to:
- Stay hydrated throughout the day
- Stretch leg muscles before bedtime
- Maintain proper electrolyte balance with adequate intake of potassium, magnesium, and calcium
- Avoid excessive alcohol consumption For immediate relief when a cramp occurs, gently stretching the affected muscle, applying heat to relax the muscle, or massaging the area can help 1.
From the Research
Causes of Night Time Leg Cramps
- The exact mechanism of night time leg cramps is unknown, but they are probably caused by muscle fatigue and nerve dysfunction rather than electrolyte or other abnormalities 2
- Nocturnal leg cramps are associated with various medical conditions, including:
- Vascular disease
- Lumbar canal stenosis
- Cirrhosis
- Hemodialysis
- Pregnancy
- Other medical conditions 2
- Certain medications are also strongly associated with leg cramps, including:
- Intravenous iron sucrose
- Conjugated estrogens
- Raloxifene
- Naproxen
- Teriparatide 2
- Idiopathic cases, where the cause is unknown, are also common, especially among older adults 3
- Endocrinologic, neurologic, and vascular disorders, as well as occupational factors, can also contribute to nocturnal leg cramps 3
Underlying Factors
- Peripheral vascular and neurologic disorders are common comorbidities associated with night time leg cramps 4
- Musculoskeletal examinations, as well as laboratory investigations, such as assessment of thyroid function and determination of platelet counts and serum levels of electrolytes, calcium, and magnesium, may be necessary to evaluate the underlying cause of leg cramps 4
Treatment and Prevention
- Quinine has been shown to be effective in decreasing the frequency of nocturnal leg cramps, but its use is not without risks, particularly in certain populations such as pregnant women and people with hepatic failure 4, 5
- Physiological methods, such as massaging and stretching, may be useful for preventing cramps in some people, but more research is needed to confirm their effectiveness 3, 5