Nocturnal cramps may cause leg discomfort and disrupt sleep. Much like restless legs syndrome and periodic limb movement syndrome, nocturnal cramps are one of the common disorders than can affect the lower extremities and alter sleep. The condition is different from these disorders in that it is usually associated with a painful contraction of the leg muscle. This pain may cause the affected individual to awaken during the night.
What Causes Nocturnal Cramps?
It can affect individuals of every age. Most commonly, the cause of the disorder cannot be identified. Sometimes structural abnormalities such as flat feet or hypermobility syndrome may contribute, and people will typically have a family history of these problems. Poor leg positioning, including prolonged sitting and standing on concrete flooring, may contribute to nocturnal cramps. Changes in fluid and electrolyte balance may cause the disorder. This may be provoked by the use of diuretic medications to treat heart failure and high blood pressure, hemodialysis as a treatment for kidney failure, or when excessive sweating occurs without sufficient salt replacement.
Are There Specific Conditions Associated with Nocturnal Cramps?
Aside from the conditions described above, there are other conditions that may also be associated with the occurrence of nocturnal cramps. These special settings include:
- Children – occur commonly and are sometimes referred to as “growing pains”.
- Pregnancy – may occur with low magnesium levels in the blood (nocturnal cramps in pregnancy are usually not a serious condition, but since low magnesium can be present in preeclampsia and eclampsia, pregnant women should notify their doctor if they experience nocturnal cramps).
- Exercise – may provoke involuntary, painful contractions.
- Neurologic conditions - Parkinson’s disease, myopathies, neuropathies, radiculopathies, motor neuron diseases.
- Metabolic conditions – diabetes, hypoglycemia, alcoholism, hypothyroidism, metabolic myopathies.
- Other conditions – anemia, Raynaud syndrome, bariatric surgery.
- Medications – beta blockers, bronchodilators, angiotensin receptor blockers, vasoconstrictors, chemotherapy, oral contraceptives.
What Will My Medical Provider Find on Examination?
Most people who are experiencing nocturnal cramps will have no abnormalities found upon physical examination by their medical provider. Additional testing such as blood work may identify a cause, but in most cases a cause is not clearly identified.
If Not Nocturnal Cramps, What Can It Be?
There are many conditions that can affect the legs that may cause symptoms similar to those experienced with nocturnal cramps. Disorders involving the nerves or blood vessels of the leg may lead to discomfort, including peripheral neuropathy, peripheral vascular disease, and claudication. Some drugs may cause muscle aches as a side effect, including statin medications. Other possible conditions include tetany caused by electrolyte disturbances, contractures due to metabolic myopathy or thyroid disease, dystonias, and compartment syndrome after excessive running.
If the condition is occurring frequently and is disruptive to your sleep, you should consult with your medical provider to investigate appropriate treatment options.
Sources
Leung, A. et al. “Leg cramps in children.” Clin Pediatr. 1997; 36:69.
McGee, S. “Muscle cramps.” Arch Intern Med. 1990; 150:511.
Sheon, R. “Nocturnal leg cramps, night starts, and nocturnal myoclonus.” UpToDate. Accessed November 2, 2009.
Whiteley, A. “Cramps, stiffness, and restless legs.” Practitioner. 1982; 226:1085.
