Uncertain, since there are no studies on humans but it stands to reason that it's a reaction to the toxic nature of the drug. Sweats are increased at night because body temp drops. It's like having a flu -- your temp is up but you have chills. This does the opposite, which doesn't suggest an increased metabolism but a suppressed one, not unlike when you're hypothyroid where you'll be sweating but your temp is low -- the opposite of a flu. Either way, it's your body telling you something's wrong and it's trying to correct it.