List of United States Presidents by military rank. The United States Constitution names the President of the United States the Commander-in-Chief of the U.S. armed forces. Many Presidents, however, also served in the military before taking office; all but 12 of 43 served. 1  1 Table of United States Presidents by military rank.  1.1 General of the Armies.
It is called circadian rhythms. Humans tend to sleep when it is dark out. I, on the other hand must work all night and sleep in the day. so my natural rhythms are screwed up. Being bored makes us sleepy, reading and watching TV makes me sleepy also physical tiredness.
Sleep apnea is a condition in which you stop breathing in the middle of the night, often several times a night. The deprivation of oxygen, as well as the constant sleep disruption, leads to constant daytime sleepiness, lethargy, and fatigue. It is also associated with more-serious conditions, such as heart disease, diabetes, and obesity.