here doxylamine comes in 12.5g pills, i remember when i wanteto them after a cocaine seshe, i took the whole box or nearly, lets say approx 100mg, fell asleep eventually but not necessarilly due to the hypnotic acton of Doxy, allthough in part, but because it was late i was unpleanstly hung over the next day, groggy, headache, bad mood....
IMO/IME for your case, no hallus, but if youre feeling slightly tired , get in bed, turn off all lights computers (etc.) and take 25mg.... (you haven't given much info on your source cause and since when you have trouble sleepting or insomnia. If your insomnia is more "severe", you evaluate,, you can take 50mg, same ritual as 25mg, depending, you might just be a bit groggy in the morning would be my main supposition. Also, a bedside lamp, and a good book to prevent tossing and turning before the medication kicks in could work....
Maybe look into "sleep hygiene" it might help you....
SLeep tight, friend!