Body temperature and blood pressure

The elderly show a decrease in the circadian rhythm of body temperature and a decrease in blood pressure with a change in the nature of the 24-hour rhythm to a 12-hour rhythm.

Hormone secretion

Hormones such as melatonin, growth hormone, prolactin, testosterone, cortisol and aldosterone show a diurnal rhythm of secretion, while the secretion of others does not change during the day, i.e. TSH, ACTH, progesterone and thyroxine. In older people, the circadian rhythm of some hormones is disrupted.

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Testosterone

In young people, testosterone secretion is greater in the morning than in the evening. In elderly men there is a marked decline in this.

Growth hormone and prolactin

The secretion of growth hormone is related to sleep, which decreases with age. Prolactin secretion is also circadian with a peak at night.