From the Guidelines
The nocturnal cortisol rise is primarily caused by the body's natural circadian rhythm, which regulates cortisol secretion through the hypothalamic-pituitary-adrenal (HPA) axis. Normally, cortisol levels are lowest around midnight and begin to rise in the early morning hours (2-4 AM), peaking shortly after waking. This natural pattern can be disrupted by several factors including chronic stress, sleep disorders like insomnia or sleep apnea, shift work that alters normal sleep-wake cycles, and certain medical conditions such as Cushing's syndrome, depression, or adrenal disorders. Medications like corticosteroids can also affect cortisol patterns. The physiological purpose of this nocturnal rise is to prepare the body for waking and daily activities by increasing blood glucose, enhancing metabolism, and promoting alertness. When this pattern is disrupted, it can lead to fatigue, mood disturbances, metabolic issues, and immune dysfunction. Maintaining regular sleep schedules, stress management techniques, and proper treatment of underlying medical conditions can help normalize cortisol rhythms.
Some key points to consider:
- The HPA axis plays a crucial role in regulating cortisol secretion, with the hypothalamus producing corticotropin-releasing hormone (CRH), which stimulates the pituitary gland to release adrenocorticotropic hormone (ACTH), leading to cortisol production by the adrenal glands 1.
- Disruptions to the HPA axis, such as those caused by Cushing's syndrome, can lead to abnormal cortisol patterns, including a nocturnal cortisol rise 1.
- Certain medical conditions, such as adrenal disorders, can also affect cortisol patterns, and proper diagnosis and treatment are essential to normalize cortisol rhythms 1.
- Maintaining a healthy lifestyle, including regular sleep schedules, stress management, and a balanced diet, can help support normal cortisol patterns and overall health 1.
In terms of diagnosis and treatment, it is essential to:
- Use a combination of diagnostic tests, such as 24-hour urinary free cortisol, late-night salivary cortisol, and dexamethasone suppression tests, to confirm hypercortisolism 1.
- Consider the use of medications, such as ketoconazole, metyrapone, or mifepristone, to decrease cortisol production in cases of Cushing's syndrome or other adrenal disorders 1.
- Monitor patients closely for signs of treatment efficacy and potential side effects, and adjust treatment plans as needed 1.
From the Research
Nocturnal Cortisol Rise
- A nocturnal cortisol rise can be caused by various factors, including noise-induced stress 2 and sleep loss 3.
- Noise exposure, even below the awakening threshold, can lead to the activation of subcortical processing centers and the hypothalamic-pituitary-adrenal (HPA) axis, resulting in increased cortisol levels 2.
- Sleep loss, whether partial or total, can also lead to elevated cortisol levels the next evening, potentially affecting the body's stress response and resiliency 3.
- Grounding the human body to earth during sleep has been shown to reduce night-time cortisol levels and resynchronize cortisol hormone secretion with the natural 24-hour circadian rhythm profile 4.
Cortisol Awakening Response
- The cortisol awakening response (CAR) refers to the rapid rise in cortisol levels observed immediately following awakening, which is distinct from the circadian rise in hypothalamo-pituitary-adrenal (HPA) activity in the morning hours 5, 6.
- The CAR is thought to be related to arousal, energy boost, and/or anticipation, although its precise function is still unknown 6.
- The CAR has been investigated in various clinical populations, including those with insomnia, and has been found to be affected by factors such as sleep architecture and night-time difficulties 6.