Читать книгу Dental Management of Sleep Disorders - Ronald Attanasio - Страница 52

Our CR or cycle is directly related to the light‐dark cycle and in turn to our sleep–wake cycle. It is derived from the Latin circa (around) and diēm (day). The human CR is slightly more than 24 hours in length and is controlled by the SCN. Adjustment to the CR, termed entrainment, is facilitated by external cues called zeitgebers (time givers), such as light, temperature, and social interaction. There are two other rhythms besides CR:

1 Infradian rhythms are greater than 24 hours, such as menstruation and seasonal depression.

2 Ultradian rhythms are shorter than CR such as heart rate, nostril dilation, and appetite.