If I were you, I'd stick with the magnesium and potassium before bedtime. The other thing to consider is if you have some compressed vertebrae in your lower back that can lead to cramping at night. I never realized I had compressed vertebrae on my lower back until I had a CT scan for something else - a kidney cyst - and that also revealed my lower 5 vertebrae were all compressed. And I was having regular cramping from that at night until I went to the magnesium/potassium supplements before bedtime. It doesn't take more than one bulging disc that results in a pinched nerve in one's back that results in some severe cramping at times. There aren't many treatments that help back problems other than epidurals, although now they have an implant, Nevro HF10 that blocks the pain signals the spine sends out. But, you may not really have a back problem anyway. It'd be nice for you to know. CT scans can show a lot of things in the body that otherwise would never be known about.