Institute for Continuing Education

An Overview of Circadian Rhythm

Course Objectives

Upon successful completion of this module, you will be able to:

• Define what is meant by the term “circadian rhythm”
• Identify the role that circadian rhythms play in human life
• Identify potential disorders related to those rhythms and indicate their causes
• Identify the available treatments for disorders in circadian rhythms

Course Information

Circadian rhythm describes the approximately 24-hour cycles that are generated by an organism. Most physiological systems demonstrate circadian variations. The systems with the most prominent variations are the sleep-wake cycle, thermoregulation, and the endocrine system.

Circadian rhythm disturbances can be categorized into 2 main groups:
1. transient disorders (e.g., jet lag; changed sleep schedule due to work, social responsibilities, illness)
2. and chronic disorders.
The most common chronic disorders are delayed sleep-phase syndrome (DSPS), advanced sleep-phase syndrome (ASPS), and irregular sleepwake cycle. Katzenberg et al suggested genetic correlation (i.e., clock polymorphisms) to circadian rhythm patterns.