Nighttime cramps are a common ailment, affecting about 60% of adults. Usually it affects older people, and the cramps last less than 10 minutes. Usually the calf muscles are affected, but its also seen in the foot and thigh muscles.

This is an issue for people, because nighttime leg cramps impact quality of life, particularly quality of sleep and energy throughout the following day.

Please note, much of this information pertains to nighttime leg cramps, not cramps in general. There are certain key differences in nighttime leg cramps versus cramps that happen throughout the day.

What are Nighttime Legs Cramps?

Nighttime leg cramps are also known as nocturnal leg cramps. These are a unique type of cramp; cramps from exercise, dehydration and other means are usually from other causes and relieved in different ways.

Nighttime leg cramps are described as sudden, involuntary, painful contractions of muscles. People describe the sensation as a spasm, tightening, twinge, swelling or muscle seizure. The muscle will sometimes cause limb movement, but not always [1].

Differential Diagnoses

When you experience nighttime leg cramps, there are a few associated conditions your health care provider will investigate, such as:

• Restless legs syndrome
• Claudication
• Myositis
• Peripheral neuropathy

Usually diagnosis is based on signs and symptoms. Lab testing and special tests are not necessary here.

What Causes Nighttime Cramps?

The exact mechanism is unknown but there has been a lot of research into this topic.

It’s now thought to be due to muscle fatigue and nerve dysfunction and not just an electrolyte dysfunction as previously believed [1].

Here are some proposed mechanisms [1]:

• ‘Civilized’ life no longer requires repetitive squatting that stretches the leg tendons and muscles; therefore, exercise would likely help, with special attention to the lower extremity
• Nighttime sleeping positions allow the foot to passively planter flex, and the calf muscles are already maximally shortened (from inactivity), so inhibited nerve stimulation leads to cramping; therefore, changing sleep position or protective bracing may help
• Nighttime sleeping positions also lead to changes in hydrostatic pressure and ionic shifts across the cell membranes of our calves, which would lead to hyper-excitability of the motor neurons and lead to cramps[2]; therefore, changing sleep position and managing fluid retention may help
• Metabolic accumulations, such as phosphate[1] in blood and local ischemia may also be responsible; therefore, full health history and testing may be helpful [2]
• Loss of motor neurons, as seen in elderly populations, is yet another theory of how these cramps occur [1] [2]
• Not only an electrolyte deficiency. Although magnesium is the most common recommendation for leg cramps, there isn’t much evidence for its use in nighttime leg cramps; indicating most people with leg cramps are having them for reasons other than a magnesium deficiency. Electrolytes are usually a concern when there is kidney disease and dehydration too, but usually those cramps persist throughout the day and during activity.

Can Medications Cause Nighttime Leg Cramps?

There are some drugs associated with leg cramps. Research shows certain medicationss have stronger associations than others. Click here to learn more about the medications associated with nighttime leg cramps.

Conditions Associated with Nighttime Leg Cramps

The following conditions are associated with nighttime leg cramps and follow the theories listed above: