Brain determines morning person or night owl

April 23, 2009 A study in the journal Science looked at the two groups. Both did a morning reaction time test and they had equal scores. Then they did the same test in the evening. This time the night owls were noticeably faster.

It turns out the early birds had more activity in an area of the brain that houses the body's master clock. So, as the day progresses, they feel more fatigued.

Researchers say, the night owls' brain's exert less pressure, allowing them to do strenuous tasks late in the day.