What Causes Excessive Perspiration In A Person With Hyperthyroidism?

Why is my boyfriend always hot? He is sweating when his feet are cold. He can't sleep well at night cause he always wake up and he is sweating.
I always tell hime, if he is a woman I would think he is going thru menopausal.
He had hyperthyroidism but has been cured and is on maintenance. He just had his blood work and everything came out Okay.
Thank you! I just want to be able to help him.
He is 42.