"Get up an hour earlier and get a head start on the day" is a common recommendation to those who have trouble getting everything done. But researchers in the field of chrono-biology - the study of the body's natural rhythms and cycles - now tell us that could be counterproductive. It depends upon whether you are a morning person or a night person. And also what is meant by earlier. If it's before 6 a.m., forget it, according to researchers. In general, that's the time we're least alert. Our ability to think clearly and react quickly is at its lowest point between 3 a.m. and 6 a.m.

The Secrets of Our Body Clocks by Susan Perry and Jim Dawson (Ballantine, 1988) reveals some interesting information on how our internal clocks operate. For instance, most of us reach our peak of alertness around noon. So perhaps delaying lunch until 12:30 or 1:00 p.m. might capitalize on our most productive period. But there's a sudden drop in the early afternoon that lasts until about 3:00 p.m., at which time our mental alertness once again begins to rise. There seems to be a good reason for the early afternoon siesta. Not good enough a reason to convince the boss, but we could schedule the mundane, low-energy tasks for that part of the day. If you are a morning person this early afternoon sag will probably be more evident.

According to the authors, your short-term memory is best during the morning hours, so studying for a test that morning or reviewing notes of a meeting would be a good idea. But long-term memory is best in the afternoon, so that's the time to study material for the following week - or for that training session for the new employee. How well you remember things depends on when you learn them, not when you recall them.

Applied to meetings, mornings are a great time for creative sessions or meetings where tough decisions must be made. But don't let them run into the early afternoon doldrums.

Everyone's clock is unique, and some may peak at 11 a.m. instead of 12 noon, but even extreme morning people and extreme night people are no greater than 2 hours apart with their circadian cycles. Morning people should do all their heavy thinking and creative work in the morning and reserve the late afternoons for the routine. Night people, although similarly alert at 11 a.m., do not experience the same late afternoon sag.

Morning people, according to Perry and Dawson, tend to have less flexible circadian rhythms so they benefit more from a structured daily routine. You could actually track your alertness and body temperature to determine how much of a morning person you really are. A morning person will usually have a temperature that rises fairly sharply in the morning, reaches a plateau by early afternoon, and begins its descent before 8:00 p.m. in the evening.

Or more simply, reflect on your behavior. If you go to bed early and wake up early, jump out of bed in the morning raring to go, do your best work early in the day and wake up just before your alarm goes off every morning, you are probably a "morning person."

But don't expect everyone else to be the same way. These biological rhythms are innate, and we should organize our lives so as to work with them, not against them.

Biological rhythms, as discussed in The Secrets of our Body Clocks, are not the same as biorhythms, which were popularized some twenty years ago. These have subsequently been discredited. But as Perry and Dawson are quick to point out, "Chrono-biology, considered an odd minor science just a few years ago, is now being studied in major universities and medical centers around the world."

Now that we can justify our lack of early morning momentum, if only someone could prove that procrastination is inherent in our genes.