The National Institutes of Health recently conducted a study on sleep and how one performs depending on the amount of sleep they received.
Researchers found that telling yourself you did get a good night's sleep, you'll actually believe and perform as if you did get enough sleep, even if you didn't.
The Institutes studied 164 people and regardless of how they slept the night before, one group was randomly told they got above average sleep, while the other group was told they had below average sleep the night before. Results showed the group who was told they had a good night's sleep, scored higher on simple addition tests, while the other group scored poorly. In conclusion, researchers said the power of the mind is at play.
People who believe they are better rested, performed as if they really are.