The brain is the most active and productive during the hours of 10:00 AM and 2:00 PM which is the time the brain is more alert and ready to learn and take in new things.
Basically your brain is in acquisition mode between those hours of 10:00 AM and 2:00 PM and then it gets less productive after 2:00 PM up until 4:00 PM and then at the hours of 4:00 PM and 10:00 PM your brain is once again productive.
But during the night your brain is mostly ready to sleep and needs time to repair itself so you need to go to sleep during the night if possible and then learn and do things during the day.
Your brain is less active and productive in the really early morning hours and at night which is why it's best to get a good nights sleep and be ready to learn new things around 10:00 AM.