Human brain not 'designed' to stay awake past midnight, study says

BOSTON -- A new study helps explain why it is so hard for most of us to stay up past midnight.

Researchers, including some at Mass. General Hospital, analyzed numerous studies to find out what happens to the human brain if it stays awake past midnight. They found that staying awake into the wee hours of the morning is associated with an increased risk of suicide, engaging in violent behaviors, the use of alcohol and drugs, and higher food intake. 

In essence, they say that the brain is pre-programmed for wakefulness during the day and for sleep at night.  But if the brain is asked to stay awake longer than usual, neurons haven't had time to recover, are tired, and can't function at their best, either that night or the following day. 

That said, this "mind after midnight" hypothesis doesn't apply to everyone.  For example, there are some people, so-called "night owls" who are more productive or creative at night.