When my ex was using opiates, he would be exhausted all the time...he'd fall asleep during anything. Passing out at 8pm, because he was "tired..." another tell-tale sign of him using was when he'd eat an excessive amount of sweets (ie: popsicles, candy, cookies, lots and lots of soda...) he was craving the sugar...not sure if it correlates to the "come down" or being high...but that's what always caught my eye after every relapse.