I've been taking trazadone for insomnia for 3 months now and it seems to be working well so far. My psychiatrist started me off with 25 mg. It wasn't enough. Then I experimented with 50 mg. Then 100 mg. It still wasn't that effective in treating my insomnia. It didn't really work too well for me until I got up to 150 mg.
I have to get up at 4:00 am 6 days a week for work. I take 150 mg trazadone at about 8:30 pm. Then I go to bed at about 10:30 pm. So I get about 5-6 hours of sleep.
One day a week I won't take trazadone and instead take 50 mg of diphenhydramine with 10 mg of melatonin just to mix it up a little.
I also throw in a low dose of xanax 0.25 mg a few times a week with the trazadone or diphenhydramine and melatonin to help with sleep and to relieve the stress and anxiety from work related stress.
My suggestion is to listen to your body and see what meds/dosage works for you with the help of a psychiatrist. Everyone's body is different.