I didnt find it all that useful TBH, it's just a sedating antihistamine so I guess it would help a little, it doesn't touch the sides of my insomia.
It's only based on my experience but other than the very short term I don't believe chemicals are the answer to sleep issues, many of them have the potential to leave you with a bigger problem than you had before.
Due to some ADs I was taking I I assume ongoing anxieties I went about 18 months without getting more than 4 hours solid a night and most nights not more than 5 in total. Once I stopped fretting about and and just got up and went online or watched a bit of TV etc. i coped OK, I always got to work every day and could function fine ( no I wasn't taking loads of speed)
I could bang on about sleep hygiene, exercise etc but I won't because I do little of any of them although I'm sure they may help. The best advice I would offer anyone would be to stop worrying about it, don't lie there trying for hours to sleep watching the clock, get up away from the bedroom and do something to take your mind off it, the worry will take more out of you than the lack of sleep IME