Is it safe to use benadryl (diphenhydramine) every night as a sleeping aid?

Not ideal: While not the most dangerous, it's not ideal. The first concern I would have, is make sure a medical professional has evaluated you for concerning causes of insomnia. This should be done first, before consider long-term use of a sleep aid, prescription or nonprescription. Second, you should make sure you sleep hygiene is optimized first before relying heavily on any sort of "pill".

Have you tried good: sleep hygiene ? If you need chronic med - would recommend melatonin over benadryl (diphenhydramine). Retire & rise same time each day. Keep bedroom dark & cool & use only for sex & sleep. Turn off tv. No naps. Exercise regularly but not in late evening. No caffeine for 6 hrs & no alcohol or tobacco w/i 2 hrs of sleep. Keep dinner moderate sized & finish at least 2 to 3 hrs before sleep. Can try warm milk, Chamomile