Internal Clock Determines How Much Sleep You Needhttp://articles.mercola.com/sites/articles/archive/2003/02/05/internal-clock.aspxAn internal clock may determine how much sleep you really need, according to new research. This internal clock, or circadian rhythm, programs your body to have a biological day and a biological night. During the biological night there are changes in hormoneenCommunityServer 2008.5 SP1 (Build: 31106.3070)