Moments of sleepiness during the day

Some people with PD experience moments of drowsiness during the day. This is usually accompanied by feelings of tiredness and you could find yourself falling into momentary sleep as you read a book or watch TV.
Again, it is possible that the medication you are taking is contributing to this and you should seek the advice of your doctor. It could also mean that you never got adequate sleep the night before. One way to ensure that you do not limit your ability to get adequate sleep at night is by ensuring that you avoid unnecessary distractions in the bedroom. You should therefore avoid reading books in bed or even watching TV. In a nutshell, make sure that your bedroom is used strictly for sleeping.
The factors that could cause sleep problems when you have PD are varied and, while you can do a lot to make your case manageable, it is always important to keep your doctor in the picture.