Cortisol, a hormone produced by the adrenal glands, has many roles including anti-inflammatory and anti-allergic actions in response to stressful situations such as illness or injury. Its production fluctuates over the course of the day with most typically produced in the early morning and very little at night. Levels tend to be minimal at around midnight and then start to rise at 2 am, peaking typically around waking.

Cushing’s Syndrome, first described by Harvey Cushing in 1932, refers to the condition caused by excess cortisol in the body, regardless of the cause. It is a rare disease with an incidence of 0.7–2.4 per million people per year and is more common in women than men (Newell-Price et al., 2006). However, studies in patients with uncontrolled diabetes mellitus or hypertension suggest that this may be an underestimation (Newell-Price et al., 2006; Sharma et al., 2015).

Epidemiology of Cushing's syndrome.

1Valassi et al., 2011; 2Sharma et al., 2015; 3Lindholm et al., 2001; 4Arnaldi et al., 2003.