Hello and good evening mate. While that is a common thing in humans yet sometimes there could be some underlying deficiencies which could be the cause. Most people get common blood work done like CBC, LFT, KFT and Lipid profile. But one must also get Ferritin, Calcium, vitamin D3, and vitamin B12 and B3. Also most of us ignore one very important supplement in our diet called Magnesium. Magnesium deficiency can cause muscle soreness, cramps and the leg sleeping thing. Try and get your blood work done once. In the mean time look for a good magnesium supplement. Many are available online. Stay healthy. Cheers!!!!