I had a moderate TBI 30 years ago, including damage to my left temporal and frontal (emotions) lobes. Regarding insomnia, your insurance may cover a sleep study. Meditation helps some with irritability and insomnia. When I can't sleep I count forwards and backwards from various increments of numbers. Redundant boring stuff helps. I don't remember numbers so I figure that is good for rewiring. Irritability? I'm a bit of a loner so I just retreat to my hobbies and interests. If the irritability and insomnia are new then it would be good to get evaluated by a neurologist for see if there are contributing factors (in my case, polyneuropathy).