A am a type 2 diabetic with sleep apnia and love my cpap etc. getting about 8 hours of sleep a night. But a couple of years ago my DR. changed me from Lipitor to Simvistatin which I think is generic Zocor. Well all of a sudden I couldn't get enough sleep. After sleeping a full 8 hours I just had to go back to bed for a little 2 or 3 hour nap after I had been up a couple of hours. After I stopped the Simvistatin and started back on Lipitor my sleep returned to normal in a few weeks. As it so happens I have a friend about my age also a type 2 diabetic with sleep apnia who experienced the same thing when on Simvistatin. After I stopped the Simvistatin I found an article saying some people taking it suffered from poor quality sleep.