Moreta is right. You could start experiencing negative side effects if you are above therapeutic dose of Tegretol. These can vary, but one I've experienced is double and blurry vision. That makes it hard to walk, definitely unsafe to drive, and is just plain disturbing.

Honestly, of my meds, Tegretol is not the one I'd choose to increase for help with sleep. I'd talk to your doctor about adding something more appropriate rather than increasing Tegretol against medical advice. Seroquel is what helps my sleep, but I take it according to my psychiatrist's direction.