My mother, for her entire lifetime, would make herself a hot cup of milk if she got up in the middle of the night and couldn't get back to sleep. (1 cup of milk contains 300 mg of calcium. ) She also added a touch of honey. She said it never failed to knock her out after 15 minutes. She also used to give this to us as children about 30 minutes before bedtime. I haven't done it in a long time, but perhaps I shall again. Great night-time ritual memory.