Cortisol (daily profile)

Cortisol is the central stress hormone of the adrenal gland (HPA axis). It follows a circadian rhythm: high in the morning (cortisol awakening response), low in the evening. With ongoing stress this rhythm can change; studies have observed both raised and flattened daily profiles. Cortisol affects the immune system, weight, sleep, blood sugar and serotonin.

What cortisol does in the body

On a signal from the hypothalamus (CRH), the pituitary releases ACTH and the adrenal cortex produces cortisol. Cortisol makes energy available: it promotes glucose production in the liver, raises blood sugar, mobilises fat and protein and strengthens the effect of adrenaline on the heart and blood vessels. At the same time it dampens inflammation and immune reactions. The rise shortly after waking prepares the body for the day; in the evening cortisol falls so that melatonin can initiate sleep. Through feedback, cortisol slows its own release.

Raised cortisol – what happens in the body?

If cortisol is persistently raised or has not fallen in the evening, the body stays in mobilisation mode: blood sugar rises, insulin action declines, fat is deposited preferentially around the abdomen, muscle and bone protein is broken down and blood pressure rises. Immune defence is dampened (susceptibility to infection, slower wound healing), and a raised evening value makes it harder to fall asleep. Causes are ongoing stress, lack of sleep, shift work and diseases of the adrenal or pituitary gland.

Low cortisol – what happens in the body?

If cortisol is low or the morning rise is missing, the body makes less energy available: morning tiredness, drops in performance, low blood pressure and a tendency to low blood sugar may follow, and inflammation is restrained less. A flattened daily profile has been observed in studies after prolonged strain. Marked deficiency due to adrenal disease (Addison's disease) is rare and should be checked by a doctor.

The interpretation is given in your report.