I have a reasonably healthy lifestyle. I eat well (but not too much, and I include plenty of veg and fruit). I drink a glass of wine a day (but no more). I am in bed by 11 (or sometimes) 10 each evening. I don't have children (or anything else that would wear me out). I walk to work and home each day (25 mins each way). I'm a 52 year old married woman. I work in an office. I am not over-worked. How come I'm always yawning as soon as I go out the door each day and start my walk to work? Would an iron supplement help?