15 Mar Super-Charging your HPA Axis: Natural Therapies Supported by Research Part IV: Sleep
Healthy habits with regards to sleep can go a long way in terms of improving our mental and body health
Sleep is a vital component of our life, required to consolidate memories gained throughout the day1. But, there is much more to it. Believe it or not, while we are asleep our brain is busy, keeping our body and mind in optimal health.
Despite the importance of sleep, a lot of us have poor sleeping habits. It is estimated that as many as 45% of all Australians suffer from sleep disturbances2. Among sleep disorders, insomnia is the most common one, affecting as many as 33% of all Australians. This condition is often associated with psychological and heart-related problems3, as well as, with a myriad of other problems. A review study, which compiled reports by people suffering from insomnia, identified detrimental effects on:
- physical functioning
- role limitation due to physical health problems
- bodily pain
- general health perceptions
- social functioning
- role limitations due to emotional health problems
- mental health
There are many other chronic sleep disorders beyond insomnia, and they have been associated with conditions like impaired cognitive functions4-5, the decline of brain function6-7, fatigue8, obesity9-10, depression11, diabetes12-13, stroke14, heart disease15-16 and psychiatric disorders17.
A lesser-known aspect of sleep involves our body’s response to stress. It influences the way our HPA axis functions, hence affecting how we respond to a stressor.
Sleep and the HPA axis
The hypothalamic-pituitary-adrenal (HPA) axis is the body’s top response system against stressful events. It is composed of three organs: the hypothalamus region of the brain, the pituitary glands and the adrenal glands. When a stressor enters the body, the HPA axis becomes active and, through the coordinated interaction of these three components, it releases different hormones that help manage the stressor.
Just as important as the HPA axis itself is the regulation of its function. Overactivation or inhibition of the HPA axis can result in detrimental health effects, affecting, for example, our body’s immune and inflammatory responses18-19.
One essential body function that can affect the function of the HPA axis is sleep. Inadequate sleeping-patterns are tightly linked with HPA function, dependent on the sleep stage. For example, deep sleep is associated with low levels of blood cortisol (the main hormone produced by the HPA axis), whereas light sleep is associated with increased cortisol levels20-21. In addition, there is a reciprocal relationship between sleep and HPA function: an overactive HPA axis can lead to light sleep and regular night-time waking, whereas inadequate sleep can promote activation of the HPA axis22.
In one study, a group of participants were sleep-deprived for one night and asked to complete a social stress test, followed by a blood test22 to measure cortisol levels. Another group completed the same tasks but had a normal sleeping schedule. The study found that, compared to the group that slept well, participants who missed a night’s sleep produced significantly higher levels of cortisol, both before and after completing the stress test.
How much you sleep is not the only factor affecting the HPA axis, but also how well you sleep. Sleep quality has been shown to be just as important as sleep length, when it comes to HPA regulation, especially for men. In one study, participants who reported having “bad quality sleep” had decreased levels of cortisol, compared to participants who reported having “good quality sleep” throughout the night. The study also found that this effect was significant in men, but not in women. This difference, the authors argued, may be due to differences in the way men and women deal with stress. There are two well-studied strategies used to regulate emotions: reappraisal and suppression. The authors suggested that, in response to stress, men tend to suppress emotions before sleep and this may cause uneasy sleep, whereas women deal with their emotions and sleep in peace. This idea is supported by previous research, showing that indeed men tend to use suppression more often than women.
Taken together, evidence strongly supports a crucial role of good sleeping habits to improve HPA function, particularly for the regulation of cortisol in your body. Altered levels of cortisol are associated with multiple health conditions. Excessive cortisol, for instance, is associated with weight gain around the face and abdomen, cognition problems, mood disorders, slow healing, and even depression. On the other hand, low levels of cortisol are associated with muscle weakness, abdominal pain, nausea and vomiting.
In addition to following a healthy diet and an active lifestyle, getting enough and good quality sleep is a proven way to improve the functioning of the HPA axis. This, in turn, will help your body maintain optimal levels of cortisol and other hormones.
If you experience insomnia, trouble to sleep or any sleep disorder, it is important to consult with a professional, like your preferred functional medial practitioner, to identify any underlying problems and design a treatment plan.
- Buysse DJ. Sleep health: can we define it? Does it matter?. Sleep. 2014 Jan 1;37(1):9-17. Read it!
- Adams R, Appleton S, Taylor A, McEvoy D, Antic N. Report to the sleep health foundation 2016 sleep health survey of Australian adults. University of Adelaide. 2016
- Chrousos G, Vgontzas AN, Kritikou I. HPA axis and sleep. InEndotext [Internet] 2016 Jan 18. MDText. com, Inc. Read it!
- Fulda S, Schulz H. Cognitive dysfunction in sleep disorders. Sleep medicine reviews. 2001 Dec 1;5(6):423-45. Read it!
- Velluto L. Sleep Disorders and Cognitive Decline. EC Neurology. 2017;8:38-44. Read it!
- Hudson AN, Van Dongen HP, Honn KA. Sleep deprivation, vigilant attention, and brain function: a review. Neuropsychopharmacology. 2020 Jan;45(1):21-30. Read it!
- McCallum SM, Batterham PJ, Calear AL, Sunderland M, Carragher N, Kazan D. Associations of fatigue and sleep disturbance with nine common mental disorders. Journal of psychosomatic research. 2019 Aug 1;123:109727. Read it!
- Stacy CB. Sleep Disorders, Somnolence, and Fatigue. Mount Sinai Expert Guides: Neurology. 2016 Apr 26:120-5. Read it!
- Naufel MF, Frange C, Andersen ML, Girão MJ, Tufik S, Beraldi Ribeiro E, Hachul H. Association between obesity and sleep disorders in postmenopausal women. Menopause. 2018 Feb 1;25(2):139-44. Read it!
- Atar M, Pirgon Ö, Buyukgebiz A. Sleep Disorders and Obesity in Childhood: A New Component in Solving Obesity. Pediatric endocrinology reviews: PER. 2019 Jun;16(4):441-51. Read it!
- Byrne EM, Timmerman A, Wray NR, Agerbo E. Sleep Disorders and Risk of Incident Depression: A Population Case–Control Study. Twin Research and Human Genetics. 2019 Jun;22(3):140-6. Read it!
- Seixas AA, Robbins R, Chung A, Popp C, Donley T, McFarlane SI, Moore J, Jean-Louis G. Sleep health and diabetes: The role of sleep duration, subjective sleep, sleep disorders, and circadian rhythms on diabetes. InSleep and Health 2019 Jan 1 (pp. 213-225). Academic Press. Read it!
- Khandelwal D, Dutta D, Chittawar S, Kalra S. Sleep disorders in type 2 diabetes. Indian journal of endocrinology and metabolism. 2017 Sep;21(5):758. Read it!
- McDermott M, Brown DL, Chervin RD. Sleep disorders and the risk of stroke. Expert review of neurotherapeutics. 2018 Jul 3;18(7):523-31. Read it!
- Elwood P, Hack M, Pickering J, Hughes J, Gallacher J. Sleep disturbance, stroke, and heart disease events: evidence from the Caerphilly cohort. Journal of Epidemiology & Community Health. 2006 Jan 1;60(1):69-73. Read it!
- Sharma N, Lee J, Youssef I, Salifu MO, McFarlane SI. Obesity, cardiovascular disease and sleep disorders: insights into the rising epidemic. Journal of sleep disorders & therapy. 2017 Mar;6(1). Read it!
- Selsick H, O’Regan D. Sleep disorders in psychiatry. BJPsych Advances. 2018 Jul;24(4):273-83. Read it!
- Heim C, Ehlert U, Hellhammer DH. The potential role of hypocortisolism in the pathophysiology of stress-related bodily disorders. Psychoneuroendocrinology. 2000 Jan 1;25(1):1-35. Read it!
- Raison CL, Miller AH. When not enough is too much: the role of insufficient glucocorticoid signaling in the pathophysiology of stress-related disorders. American Journal of Psychiatry. 2003 Sep 1;160(9):1554-65. Read it!
- Born J, Kern W, Bieber K, et al. Night-time plasma cortisol secretion is associated with specific sleep stages. Biol Psychiatry 1986;21:1415-1424. Read it!
- Follenius M, Brandenberger G, Bandesapt JJ, Libert JP, Ehrhart J. Nocturnal cortisol release in relation to sleep structure. Sleep 1992;15:21-27. Read it!
- van Dalfsen JH, Markus CR. The influence of sleep on human hypothalamic–pituitary–adrenal (HPA) axis reactivity: A systematic review. Sleep medicine reviews. 2018 Jun 1;39:187-94. Read it!
- Minkel J, Moreta M, Muto J, Htaik O, Jones C, Basner M, Dinges D. Sleep deprivation potentiates HPA axis stress reactivity in healthy adults. Health Psychology. 2014 Nov;33(11):1430. Read it!