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.
A answered. Sleep disorders can affect the body in many ways. If you are not getting adequate sleep, you may feel very tired during the day. You may also feel irritable, have trouble concentrating or remembering things, and get headaches. Sleep disorders can also cause stress and anxiety, and can even lead to a weakened immune system, which may lead to illness.