Asked by: Charlotte Birch, Ashford
Cramp is an involuntary and sustained muscle contraction. It can be caused by electrolyte imbalance, certain neuromuscular disorders or by drug use. But it mostly happens when we're resting. One theory is that cramps occur when a muscle that is already shortened tries to contract. In bed, your knees are normally slightly bent and your feet pointed down. This leaves your calf muscles shortened so if they receive an erroneous signal to contract, you're more likely to suffer a cramp spasm.
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