If your problem is GETTING to sleep I'd say Ambien, I take it when my brain won't stop running when I lay down even tho a couple minutes prior I could barely keep my eyes open or focus on anything... I'd sleep soundly throughout the night and not feel groggy at all, actually really refreshed because ambien (zolpidem) has a very short half life (like two hours) so it just knocks you out and you sleep quasi-naturally the rest of the night.
There isn't much sleep medications that won't leave you groggy the next morning... that is just a side effect that has to wear off in time. Trazodone and seroquel is what most Doctors like to dish out for sleep problems and they will knock you out but leave you SUPER groggy the next morning, out of the myriad amounts of sleep aids I've tried Seroquel and Trazodone have the worst next day effects, imo.
My favorite sleep medication is temazepam, it is a benzo that works WONDERFULLY for sleep. I would sleep a solid 8-10 hours and when I woke up I would have that natural just woke up sleepyness but no groggyness. But it is rather hard to get prescribed since it is a pretty strong benzo....
If you want to go natural I found a natural supplement by Sundown Naturals called Super Snooze which is: Calcium, Magnesium, Valerian Root, Hops, Chamomile, Passion Flower, Taurine, and Melatonin. It makes me drowsy as fuck when I take it at night and I don't feel groggy the next morning, I found this when I Was detoxing off heroin last time and I wanted to try a natural route... this helped a lot.
Now my psych has prescribed me Mirtazapine (remeron) for sleep purposes along with the anti-depressant benefits... it works AWESOME and it helps me sleep when I'm going through heroin withdrawals so that's a win!