As a student I want my study time to be as effective as possible. If you understand how the brain works than you will be a successful learner. That means that cramming should be a thing of the past, study time should be planned on what you need to learn and your environment should be optimized.
Sleep is not optional. It will actually help your brain to store information into long-term memory so you can recall it for an exam or paper. Slow wave sleep happens during the first third of the night, if you miss this time you are missing the time when you take short-term memory consolidate it and put it into long-term memory. Your brain will recall information more effectively from long-term memory
A short nap or walk will help you to concentrate. Your brain can only absorb so much information; get up after 45-50 minutes and nap for 20 minutes or go for a walk, this will help you to clear out that short-term memory so it can store more information.
If you are studying fact the best time to study is between 3 pm and 5 pm during the day. This is when your brain will learn these pieces of information optimally.
If you are learning skills then study between 6 pm and 8 pm. This is the best time for your brain to process skill memory.
Clutter is the enemy. Clutter in your study environment or in your sleep environment will distract you. This is true if you have ADD or if you are the average person. It is worth the 10 minutes to declutter your space before you start studying. This does not mean you need to clean the whole house, just try to make the area you are working in organized.
Noise or no noise that is personal. Some people are distracted by the least sound, if this is the case white noise such as rain, ocean sounds, or soft music will help decrease distractions. If you find this distracting it might benefit you to be in a quiet place.