For years, I have been telling my patients to make sure they get enough sleep. I recommend at least 8 hours of sleep every night. Many people rebel at this recommendation because they have "too much to do."
I understand that fitting in 8 hours of sleep can be difficult in some situations. To maintain your health you must prioritize sleep! Even throughout my years as a full-time student, and mother, I prioritized sleep and on average slept at least 8 hours every night. Being fully rested helped me to maintain not only my concentration, but also my health.
Think of how far you fall behind when you get sick. Many people try to continue their normal activity level when sick, but this is a bad idea. They simply stay sick longer and may spread the infection onto many other people.
A recent study found that people who slept under 7 hours every night were 3x as likely to catch a cold as those who slept longer. Other studies have recommended at least 7 hours of sleep to reduce the risk of heart disease. I think that sleeping at least 8 hours is a simple cheap way to maintain health. Why spend lots of money on drugs to treat illnesses that can be prevented by adequate sleep?