We all have a biological clock, and I am not talking about the biological clock some women refer to when discussing the sudden need to have a baby. I am talking about the daily clock of the circadian rhythm, the energy ups and downs we all experience through out the day.

Scientist have located the clock that controls the circadian rhythm. It is actually a pair of pinhead-sized structures that together contain about 20,000 neurons, that is housed deep on our brains, near the optical nerve. Animals, plants and microbes display circadian rhythms; it's part of deep biology. While circadian rhythm, the pattern of sleep and awake cycles, is affected by light, but people living in complete darkness will adjust to a 25 hour clock with normal sleep / wake patterns. Personally, I would not like to be a subject in a study that determined this.

Want to know how the circadian rhythm works throughout your day? then read more

According to Women's Health the daily rhythm goes something like this:

• 6:30 a.m. to 7:00 a.m. - Sleep Inertia
  During the first 30 minutes you're awake, thinking and reaction times are substantially impaired.

• 7:00 a.m. to 12:00 p.m. - Morning Hustle
  Between breakfast and lunch, your sense of alertness peaks. This is the time to get things done.

• 12:00 p.m. to 5:00 p.m. - Nap Time
  At some point in the afternoon, we experience an energy drag that usually lasts about 2 hours. The Spanish siesta might have some science behind it.

• 5:00 p.m. to 8:00 p.m. - Sunset Spike
  A rise in energy occurs making this a very difficult time to nap.

• 8:00 p.m. to 6:30 a.m. - Back to Bed
  The chemical melatonin, which helps you to sleep, floods your body as you snooze.

Fit's Tip: According to the circadian rhythm it is best to do all your heady work in the morning and save all those menial tasks for the afternoon.