Sleeplessness and Circadian Rhythm Disorder Topic Guide
Sleeplessness and Circadian Rhythm Disorder: A person's circadian rhythm is an internal biological clock that regulates a variety of biological processes according to an approximate 24-hour period.
Seasonal Depression (SAD) Seasonal affective disorder (SAD) is a type of depression that is tied to seasons of the year. Symptoms include depressed mood, fatigue, feelings of worthlessness, and poor concentration. Treatment may incorporate bright-light therapy and antidepressants.