Accidental double dosage

I've been taking fluoxetine for about 2 months and recently changed the time I take the medication due to not being able to sleep at night. I took my pill at night like I'm suppose to and this morning I went to take my other medication, but took another 20mg instead. I feel fine other than drowsiness plus dry mouth. I'm just curious if anyone else has done this before and if so what happened?