I have been taking citalopram since May but have just been switched to mirtazapine as was having trouble sleeping and experiencing really bizarre vivid dreams when I did sleep. Took first 15mg mirtazapine last night and I slept like a log (I did wake up at 4 which have been doing but went straight back to sleep). Trouble is I am in a complete fog today and feel totally exhausted. I'm terrified of dropping off before I have to collect children from cricket! Can anyone reassure me that this will wear off after a week or so? Concerned about returning to work when new term starts!