Sleep is the state of natural rest observed in the mammals and birds, and in many reptiles, amphibians, and fish. It is very important and is generally characterized by a reduction in voluntary body movement, temporary blindness, decreased reaction to external stimuli, loss of consciousness, a reduction in audio receptivity, an increased rate of anabolism (the synthesis of cell structures), and a decreased rate of catabolism (the breakdown of cell structures).So it is very important; you sleep a big part of the day. Many scientists believe that memory depends on sleep. Organs and parts of your organism find the rest they need in sleep. Since the light bulb was made the time that people sleep is shorter and shorter. Self-reports of total sleep times, both habitually and on the morning after a polysomnogram (PSG), or a sleep test, tend to be higher than objectively measured sleep times, according to a study published in the October 15 issue of the Journal of Clinical Sleep Medicine. Graciela E. Silva, PhD, of Arizona State University, analyzed a total of 2,113 subjects who were 40 years of age or older. The participants were 53 percent female, 75 percent Caucasian and 38 percent obese.

The result has showed that the mean habitual sleep time was 422 minutes, while the mean morning estimated sleep time was 379 minutes and mean PSG total sleep time was 363 minutes. The difference is about an hour. Further, obese and higher educated people reported less sleep time than their counterparts. Similarly, small but significant differences were seen for sleep latency.

“The findings from this study suggest that results from studies subjectively assessing sleep times may not be comparable to those using objective determinations,” said Dr. Silva. The thing that you can learn here is that there is a need to try to be objective when you are thinking about your health.