i worked with a nurse on nightshift who was pregnant and she did fine. her only complaint was lack of sleep after baby was born. i can say i had that problem as well when i worked nights after my daughter was born, but doesn't most new parents have that problem? as long as you continue with the dark room and fan i doubt you'll have any problem with sleep. during your first trimester you will be tired most of the time anyhow. once you progress sleep will become uncomfortable because of your growing stomach and all. ask your husband to rub your back to help you relax, besides it's your turn to be pampered since you'll be carrying the baby for 9 months!