i have a script for sonata i recieved a few months back for my intermittent insomnia. The doc didn't want to prescribe valium because it would deprive me of my REM sleep and I would wake up feeling groggy.
Zaleplon is a fast acting sedative hypnotic, which leaves your system in four hours or so, allowing you to experience REM sleep and wake up feeling refreshed. The first few times I used it, it worked GREAT. Woke up refreshed, on time, not at all groggy.
However, I have been using it on and off for two months and the past couple times it has not worked at all. I must have developed some sort of serious tolerance to it. This happened slowly, I noticed about a few weeks ago that I would wake up after about 4 hours and have a little trouble getting back to sleep...then the past couple times it did nothing. I ended up taking 40 mg over the course of the night and sleep never came.
That made me sad and grouchy the next day.