How do we keep in time? Understanding human circadian rhythms.

1. Circadian rhythms tend to have a periodicity of 20-28 hours. Physiological variables such as body temperature, blood pressure, and intraocular pressure show fluctuations over each 24-hour period. 2. Circadian rhythms have an endogenous component produced by a 'clock' inside the body, and an exogenous component produced by our rhythmic lifestyle and environment. 3. An understanding of circadian rhythmicity is relevant to nurses, as variations in physiological parameters may have implications for patient care and treatment. 4. Discussion of circadian rhythmicity and its implications should be included in Project 2000 courses to increase understanding of how we 'keep time'.