Researchers from the University of Alberta took 18 participants (admittedly, a very small sample) and concluded that a morning person's strengths generally remain constant throughout the day, but the same doesn't hold true for night owls, who tend to do their best work exclusively in the evenings. According to the article:
That may be because evening people show increased motor cortex and spinal cord excitability in the evening, about 9 p.m., meaning they had maximal central nervous system drive at that time...Morning people, on the other hand, never achieve this level of central nervous system drive because the excitability of the motor cortex does not coincide with the excitability of the spinal cord. In other words, these two measures never peak at the same time...
Based on these findings, the researchers concluded that early birds are most excitable at 9 a.m, and that night owls probably couldn't become morning people, even if they forcibly tried to change their habits, say by sitting in front of a very bright light early in the morning and taking melatonin to sleep earlier.
What do you make of the findings? Do you consider yourself a morning or night person, and how—if at all—do you feel it affects your performance? Whatever your classification, you can help yourself get the best sleep possible by improving your sleep posture.