"my insomnia has gotten out of hand recently and diphenhydramine and melatonin were no longer working for me. i received the sample pack of suvorexant from my doctor. i took 20 mg and it had absolutely no effect on me at all. took a few hours to go to bed and woke up less than 4 hours later. what a joke! maybe it works for others and maybe i have some problem with my thyroid for example (still waiting to receive results from my bloods) that causes this not to work for me."