I have periodic insomnia.  About once a month, sleep will not come.  My brain is not racing.  Physical ailments are minimal and don’t usually keep me awake.  Sometimes, it happens before a calm day and I can sleep it off with no problems except the glare from the wife for sleeping the day away.  Other times, it’s pure hell going through a day on an hour or two of sleep.  Today is one of those days.