Here is some bad news for early birds and/or for go-getters who like to pull all-nighters. Researchers in Germany tested measures of brain function among subjects subjected to 28 hours of "constant wakefulness". These functions included perception, motor ability, and cognitive decision making - all of which performed most poorly in the early hours of the morning. Slowed reaction time affected both perception - especially one's capacity to respond quickly to visual stimuli - and motor ability, including strength, dexterity and reflex speed. The researchers determined that the slower reaction time was ultimately caused by a decline in central processing speed, as indicated by tests of cognitive performance administered at various points during the experiment. These tests focused specifically on the ability of subjects to successfully complete multiple tasks at the same time.

Although cynics might conclude that your mental powers will naturally decline the longer you go without sleep, the researchers linked the declines to the circadian rhythm of the subjects, as measured by "salivary melatonin concentration and body temperature." Circadian rhythms affect human physiology depending on the time of day, whether or not the subject is asleep.

This research suggests that white collar workers who get up at, say, 5:00 AM to go to work should exercise caution during their commute and remain realistic about the limitations of their work performance until later in the day. Ditto for anyone burning the midnight oil. Such findings, if publicized, have the potential to put a damper on the overuse of "flextime" - not to mention on the hopes of those who like to start their workday at the crack of dawn. The benefits of beating the traffic by driving to work early might actually be offset by sleepiness and diminished reflexes.

"Multitasking Is Hardest In The Early Morning" from BrightSurf.com