Has he seen a neurologist? Has he had any EMG's or Nerve conduction studies? Are his feet numb? Does he have any other medical issues or take medication? Does he have any anxiety or other psychological issues?
check out Benign fasciculation syndrome ..
Hi there. True cramps are caused by hyperexcitability of the nerves that stimulate the muscles. the causes could be injury causing persistent muscle spasm as a protective mechanism, vigorous use of muscles following activity, rest cramps but your husband doesnot have these at rest, dehydration causes true cramps in hot weather and can be an early sign of heat stroke, loss of sodium, cirrhosis of liver where you have unusual fluid distribution due to ascites. Low blood calcium, magnesium, increase excitability of both nerve endings and muscles that they stimulate, vitamin D deficiency, low potassium levels .
Treatment would include stretching of muscle which can stop the cramp. He can stand up and walk around. He can try flexing his ankle by pulling toes up toward the head while in the bed with the leg as straight as possible. Avoid the possible triggers like fluid and electrolyte imbalance. Consult your neurologist on any other remedy that he can suggest.