Glossary
| Amplitude | The maximum variation measured from mean |
| Acrophase | Phase angle corresponding to the peak value of the rhythm |
| Biological (peripheral) clock | Self-sustained circadian oscillation in absence of external periodic input |
| Central (master) clock | The suprachiasmatic nucleus located in the basal hypothalamus of the brain, receiving external information via the retina |
| Chronobiology | Study that examines timing processes or biological rhythms |
| Chronotype | The propensity for the individual to sleep at a particular time during a 24-hour period; it can be broadly categorised into three groups: (1) morning-type (wake up early and sleep early, peak of physical and mental activity during early part of the day); (2) evening-type (wake up late and sleep late, with peak physical and mental activity during end part of the day) and (3) neither |
| Chronotherapy | Synchronisation of drug concentration to rhythms in disease activity |
| Circadian rhythm | Biological processes that display oscillation over 24-hour periodicity |
| Diurnal variation | Variation during the day between dawn and dusk |