Well, since the clonazepam has about a 12 hour effectiveness in the body, you could possibly take another small amount, maybe that 0.75 mg 12 hours after the previous dose. Taking 2 mg total of clonazepam is a low dose, not a high one. As for the antihistamines, Benadryl (diphenhydramine) will make you drowsy no matter when you take it. As for the doxylamine succinate, just cut the tablet smaller and smaller to get to the dose where, after you take it before bed, it leaves you with no hangover in the AM. My wife has been taking temazepam 30 mg before bedtime, along with 100 mg of trazadone for decades now, and she is in her 60's with no side effects from those doses. It's just that you must try and try again with different sleep aids until you find what works. I agree with a previous commenter who said to see a psychiatrist, yet there are sleep specialists MDs who would take more of a vested interest in your case I think.