3 ms·I have bmi around 18 and sleep is my biggest problem since my first memories.by lrem 14y agoI have bmi around 18 and sleep is my biggest problem since my first memories.eru 14y agoUnderweight can be as much of a problem as overweight.lrem 14y agoMisremembered the number. It's actually 19-19.5, quite stable over the years.