Seroquel absolutely can cause drowsiness, it's one of the most common side effects
. How long have you been on it? A lot of times, those side effects
will start to dissipate after a week or two of taking a medication. It sounds like you've been on it a while?
Also, it could be very likely that your dosage is just a tad too high. I would recommend talking to your doctor and seeing about maybe making some adjustments and then reassessing the Seroquel after a few weeks.