"In England, I didn't sleep at all," Riddle said of his recent UFC fight against Che Mills, which was held at London's Wembley Arena. "I slept about two hours at a time. I just can't sleep. I have a hard time eating. And it's not just, 'Oh, I can't sleep.' The reason I can't sleep is I just keep thinking – and not bad things or horrible things or anything like that, but I just can't slow my mind down.
"Like I'll be like, 'Go to sleep, Matt. Go to sleep. Go to sleep.' And then something else will just start popping in my head. I won't stop thinking about that. Then another thing. Then it's three things at once. Before I know it, I'm like sweating, and I'm just like, 'Why?' Because I'm just thinking too hard, and I can't slow things down. When I use medical marijuana, I just feel normal."
Riddle rebounded from a recent suspension for a positive marijuana test, by notching a decisive victory over Mills.
While he will respectfully accept that he's not allowed to smoke at least three weeks before a fight, he says he'll continue to be an advocate for marijuana reform.
"Right now what they tell me is, 'Our industry frowns upon it. You can't use it. You can't test positive for it, and right now even if you don't test positive for THC and you test positive for metabolites, you still fail,'" Riddle explained to MMAjunkie.com Radio (www.mmajunkie.com/radio). "I deal with it, and honestly I'm an advocate for it. I think it should be legal, and it's the only drug ever that's never killed somebody."