What Makes Us Tick
Our master clock is really just a tiny cluster of nerve cells about the size of this “v.” Called the suprachiasmatic nucleus (SCN), it lies deep within the brain in an area called the hypothalmus, which controls such basic functions as food intake and body temperature.
Although the SCN has no direct contact with the outside world, it is influenced by light. How is that possible? Light receptors in the back of the eyeball send messages along nerve fibers to the SCN. The SCN takes the information, interprets it, and passes it on to another tiny structure in the brain, the pineal gland. This gland secretes the so-called time-keeping hormone melatonin, levels of which increase at night. The SCN also sends information about time to the pituitary gland, which triggers the secretion of more hormones that profoundly influence the immune system.
It is increasingly clear that adhering to this natural body clock and scheduling your activities by it can help keep you energized and healthy in curious ways that are now coming to light. Here are some time-wise tips based on these findings.
Morning Is the Best Time to…
- Become pregnant. About 50 percent of hopeful couples—most of whom are perfectly healthy and fertile—don’t conceive in the first three months of having unprotected sex. Trying in the morning might help. Cornell University Medical College research shows that men tend to produce more sperm around 6:00 a.m. than at other times.
- Eat to lose weight. A University of Minnesota study suggests that the body burns calories better early in the day. People who ate only one 2,000-calorie meal a day for a week lost weight if they ate their meal in the morning—yet they gained weight if they ate the same meal at night!
Eating once a day is unrealistic for most people, and even unhealthy for some (diabetics, for example), but the study suggests that merely consuming more of your calories earlier in the day rather than later is better for weight control.
- Elucidate like Einstein. Concentrating on complex tasks is easier in the mid-morning. Levels of cortisol, a stress hormone that also boosts mental alertness, start building about two hours before you wake up and typically peak at about 10:00 a.m.
Afternoon Is the Best Time to…
- Nap. The human body is naturally inclined to rest in the middle of the afternoon.
- Be tested for allergies. As explained by chronobiologist Michael Smolensky, Ph.D., of the University of Texas at Houston School of Public Health, sensitivity to skin tests can be three times greater in the morning than later in the day. One small, unpublished study, he says, found that 20 percent of allergen skin tests were negative when performed in the morning but positive later in the day.
- Exercise. Muscles are relaxed, and joints move more easily when body temperature is higher.
Evening Is the Best Time to…
- Cure an ulcer. Peptic ulcer medications are best taken around 6:00 p.m., with dinner. That way they can better block the normal late-night peak in secretion of stomach acid.
- Visit a sick friend. After about 9:00 p.m., your number of white blood cells is at its natural high, providing you with stronger protection against any germs you might encounter.
- Make love. Don’t wait until the late-night news is over. Testosterone levels peak about 10:30 p.m. in both men and women—and the higher the testosterone, the more one’s thoughts turn to romance.