Sweating is a know side effect of Seroquel. It can also be a symptom of a serious adverse reaction called Neuroleptic Malignant Syndrome or NMS. NMS is a potentially fatal complication of antipsychotic medications such as Seroquel. If you have some of the following symptoms please see your doctor:
high fever
muscular rigidity
rapid heartbeat
altered mental state
tremor
dark urine
profuse sweating
rapid breathing
incontinence
Of course as Ho-Chi-Minh mentioned there could also be other causes for the night sweats. It can be hard to know where specific side effects are coming from when you take a number of different drugs.
I have heard of many others having night sweats and/or sweating in general from Seroquel but I don't know if there is a huge amount you can do to stop it other than switching to a different drug. You could shower before bed, keep your room cool (but not
too cold), and use only natural bedding - NO synthetic down/polyester/etc, all-cotton sheets, etc.
Here is a list of natural ways to reduce excessive sweating.