I started taking simvastatin about 3.5 weeks ago, I've not had a ...

I started taking simvastatin about 3.5 weeks ago, I've not had a decent nights sleep since. My entire life I've been a really deep sleeper, fire alarms have failed to wake me up in the past (don't worry, it was only burning toast in a student house). Yet since I started on 10mg to address a cholesterol level of 6.7, I've been waking up 5-6 times a night. The result is that I wake up in the morning still tired. My Dr. has suggested that I try taking the pills in the morning rather than at night, failing that he will try reducing the dosage, but isn't the smallest dose 10mg ??