The instant release version is usually prescribed for daytime use. Most neurologists will tell you that the controlled release version is less predictable in its absorption, ie they find they cannot rely on all the levodopa this pill contains has been taken up and not wasted in the system. The controlled release version, however is widely prescribed for night time use. I take one at bedtime and one in the middle of the night. Their slow release does helps me sleep better for longer periods.
I take a total of 14x 62,5mg tablets of instant release during the day.