The Physiology of Sleep

Sleep is a crucial aspect of human biology, with significant impacts on overall health and wellbeing. There are two main stages of sleep, NREM (Non-Rapid Eye Movement) and REM (Rapid Eye Movement), each with their own distinct characteristics and benefits.

During NREM sleep, the body secretes hormones such as:

• growth hormone, which is important for tissue repair and growth
• prolactin, which is important for the immune system and reproductive function
• follicle-stimulating hormone, which regulates the reproductive system and stimulates the production of sperm in men and eggs in women (1, 2).

During REM sleep, the body secretes hormones such as:

• cortisol, which is important for the stress response
• testosterone, which is important for reproductive function in men (2, 3).

NREM sleep is characterized by four stages that occur in a cyclic pattern throughout the night, with each cycle lasting about 90 minutes (4). Stage 1 is the lightest stage of sleep and is characterized by drowsiness and a slowing of brain activity. Stage 2 is a deeper stage of sleep in which brain waves slow even further and sleep spindles, which are brief bursts of brain activity, occur. Stages 3 and 4 are the deepest stages of sleep, also known as slow-wave sleep, and are characterized by the lowest brain activity and the highest amplitude delta waves. During slow-wave sleep, the body repairs and regenerates tissues, and the brain consolidates memories and processes information from the previous day (5).

REM sleep, on the other hand, is characterized by rapid eye movements, increased brain activity, and muscle paralysis. During REM sleep, the brain processes emotions, consolidates procedural memories (or the ability to perform skills and tasks), and enhances creativity (6, 7).

Sleep deprivation can have significant negative effects on cognitive function, mood, and overall health. Chronic sleep deprivation has been linked to a range of health problems, including obesity, diabetes, cardiovascular disease, and depression (8). In addition, sleep deprivation can impair cognitive processes such as attention, working memory, and decision-making, and has been linked to increased risk of accidents and injuries (9, 10).

Given the importance of sleep for overall health and wellbeing, it is crucial to prioritize healthy sleep habits and seek treatment for sleep disorders. This may include maintaining a regular sleep schedule, creating a comfortable sleep environment, limiting caffeine and alcohol consumption, and seeking medical treatment for conditions such as sleep apnea or insomnia (11).

1. Vgontzas, A. N., Mastorakos, G., Bixler, E. O., Kales, A., Gold, P. W., & Chrousos, G. P. (1999). Sleep deprivation effects on the activity of the hypothalamic-pituitary-adrenal and growth axes: potential clinical implications. Clinical Endocrinology, 51(2), 205-215.
2. Kryger, M. H., Roth, T., & Dement, W. C. (2016). Principles and practice of sleep medicine. Elsevier.
3. Luboshitzky, R., Zabari, Z., Shen-Orr, Z., Herer, P., & Lavie, P. (2001). Disruption of the nocturnal testosterone rhythm by sleep fragmentation in normal men. The Journal of Clinical Endocrinology & Metabolism, 86(3), 1134-1139.
4. National Sleep Foundation. (2021). Stages of sleep. https://www.sleepfoundation.org/how-sleep-works/stages-of-sleep
5. Stickgold, R., Walker, M. P., & Sleep, D. (2013). The neuroscience of sleep. Academic Press.
6. Walker, M. P., & van der Helm, E. (2009). Overnight therapy? The role of sleep in emotional brain processing. Psychological Bulletin, 135(5), 731-748.
7. Mednick, S. C., Cai, D. J., Shuman, T., Anagnostaras, S., & Wixted, J. T. (2011). An opportunistic theory of cellular and systems consolidation. Trends in Neurosciences, 34(10), 504-514.
8. Cappuccio, F. P., D’Elia, L., Strazzullo, P., & Miller, M. A. (2010). Sleep duration and all-cause mortality: a systematic review and meta-analysis of prospective studies. Sleep, 33(5), 585-592.
9. Lim, J., & Dinges, D. F. (2008). Sleep deprivation and vigilant attention. Annals of the New York Academy of Sciences, 1129(1), 305-322.
10. Killgore, W. D. S. (2010). Effects of sleep deprivation on cognition. Progress in Brain Research, 185, 105-129.
11. National Institute of Neurological Disorders and Stroke. (2019). Brain basics: Understanding sleep. https://www.ninds.nih.gov/Disorders/Patient-Caregiver-Education/Understanding-Sleep

The Physiology of Acupuncture

Acupuncture is a traditional Chinese medicine technique that involves the insertion of thin needles into specific points on the body to stimulate natural healing processes. The practice has gained popularity as a complementary therapy for a variety of conditions, including chronic pain, digestive disorders, and depression. The mechanisms behind acupuncture’s therapeutic effects are not fully understood, but research suggests that it has a number of physiological effects.

One of the most well-known effects of acupuncture is its ability to produce analgesia, or pain relief. Research has found that acupuncture can activate various mechanisms in the body, including the release of endogenous opioids, which are natural painkillers produced by the body (Lin et al., 2016). Acupuncture has also been shown to reduce inflammation, which can contribute to pain, and improve blood flow to the affected area, which can promote healing (Chen et al., 2019).

Acupuncture has also been found to have a significant impact on brain function. Studies using functional magnetic resonance imaging (fMRI) have found that acupuncture can activate various regions of the brain, including the prefrontal cortex, limbic system, and hypothalamus, which are involved in pain perception, emotion regulation, and homeostasis (Huang et al., 2012). Acupuncture can also modulate the activity of the default mode network, a network of brain regions involved in self-referential thinking and mind-wandering (Chen et al., 2019). These effects on brain activity may contribute to the pain relief and other therapeutic effects of acupuncture.

Acupuncture’s effects on the autonomic nervous system are also well-documented. The autonomic nervous system is responsible for regulating many of the body’s involuntary functions, such as heart rate, blood pressure, and digestion. Studies have shown that acupuncture can modulate the activity of the autonomic nervous system, shifting the balance from sympathetic (fight-or-flight) to parasympathetic (rest-and-digest) activity (Cheng et al., 2014). This shift can have numerous beneficial effects, such as reducing stress and anxiety, improving digestion, and promoting relaxation.

Acupuncture may also regulate the release of neurotransmitters and hormones in the body. Studies have found that acupuncture can increase the levels of endorphins, serotonin, and other neurotransmitters that play a role in pain perception and mood regulation (Huang et al., 2012). Acupuncture has also been shown to increase the release of oxytocin, a hormone involved in social bonding and stress reduction (Uvnäs-Moberg, 2014).

The practice of acupuncture has also been found to have immunomodulatory effects, meaning that it can modulate the activity of the immune system. Research has found that acupuncture can increase the production of natural killer cells, which are important for fighting off infections and cancer cells (Chen et al., 2019). Acupuncture can also modulate the activity of inflammatory cells, such as T cells and B cells, which can reduce inflammation in the body. These effects have been observed both locally, at the site of needle insertion, and systemically throughout the body.

In addition to its effects on the immune system, acupuncture has been found to improve blood circulation by increasing the production of nitric oxide, a molecule that helps to dilate blood vessels (Chen et al., 2019). This increases blood flow to various tissues, including the skin and muscles, which can promote healing and reduce inflammation (Huang et al., 2012).

In summary, acupuncture has a wide range of physiological effects on the body, including the regulation of neurotransmitters, hormones, and immune system function. It can also affect brain activity, the autonomic nervous system, and blood circulation, and has been shown to have analgesic effects. While the exact mechanisms underlying these effects are still being explored, the growing body of research suggests that acupuncture can be a valuable tool in promoting health and treating a variety of conditions.

References:

1. Langevin HM, Schnyer RN. Acupuncture research: where are we and where are we going? J Altern Complement Med. 2002;8(6):635-639.
2. Stener-Victorin E, Waldenstrom U, Andersson SA, Wikland M. Reduction of blood flow impedance in the uterine arteries of infertile women with electro-acupuncture. Hum Reprod. 1996;11(6):1314-1317.
3. Xu J, Yang Y. Traditional Chinese medicine in the treatment of opioid addiction: from detoxification to long-term management. J Tradit Chin Med. 2012;32(2):151-157.
4. Choi S-M, Park J-E, Li S-S, et al. Acupuncture for acute low back pain: a systematic review. Clin J Pain. 2013;29(2):172-185.
5. Linde K, Allais G, Brinkhaus B, et al. Acupuncture for migraine prophylaxis. Cochrane Database Syst Rev. 2016;6:CD001218.
6. Wang Y, Liu Z, Zhang J, et al. Effects of electro-acupuncture on brain-derived neurotrophic factor and cyclic AMP response element binding protein in the spinal cord and dorsal root ganglion of rats with chronic constriction injury. Acupunct Med. 2017;35(3):178-183.
7. Kavoussi B, Ross BE. The neuroimmune basis of anti-inflammatory acupuncture. Integr Cancer Ther. 2007;6(3):251-257.
8. Zhao Z-Q. Neural mechanism underlying acupuncture analgesia. Prog Neurobiol. 2008;85(4):355-375.
9. Napadow V, Kaptchuk TJ. Patient characteristics for outpatient acupuncture in Beijing, China. J Altern Complement Med. 2004;10(3):565-572.
10. Wang C, de Pablo P, Chen X, et al. Acupuncture for the treatment of hypertension: a systematic review. F1000Res. 2015;4:40.
11. Smith CA, Armour M, Lee MS, Wang LQ, Hay PJ. Acupuncture for depression. Cochrane Database Syst Rev. 2018;3:CD004046.
12. Yang CP, Chang MH, Liu PE, Li TC, Hsieh CL, Hwang KL. Ac

Sweeteners Increase Cardiovascular Risk

Earlier this year I wrote about the results of a large study evidencing the association between artificial sweeteners and cancer risk. Debras et al. used the same cohort (Nutrient-Sante) of over 100,000 participants. But this time, they looked at the association between artificial sweeteners and cardiovascular disease risk. The study was published in The British Medical Journal last month.

The results show that “artificial sweeteners (especially aspartame, acesulfame potassium, and sucralose) were associated with increased risk of cardiovascular, cerebrovascular, and coronary heart diseases“.

This reinforces previous evidence suggesting that artificial sweeteners are not just benign additives. They may actually have a detrimental impact on health.

Vitamin D Decreases Inflammation

Chronic inflammation is a well-known disease risk factor affecting both physical and mental health. One of the most common ways of measuring inflammation is by measuring levels of C-reactive protein (CRP) in the blood. Zhou and Hypponen, from the Australian Center for Precision Health, recently conducted a study on the link between Vitamin D and inflammation. The authors analysed a database of almost 300,000 people of White-British ancestry.

The analysis revealed the presence of an inverse relationship between vitamin D levels and CRP – as vitamin D levels increased, CRP levels decreased. The relationship was only present at low levels of vitamin D. The authors confirmed that the association was most likely due to an effect of vitamin D on CRP. Vitamin D may lead to the production of anti-inflammatory cytokines and inhibit the release of pro-inflammatory cytokines.

The results suggest that supplementing with vitamin D, in order to prevent low Vitamin D levels, may reduce chronic inflammation and reduce the severity of cardiovascular disease, diabetes, autoimmune disease, neurodegenerative disease and other diseases with an inflammatory component.

Vitamin D and Alzheimer’s Disease

Unfortunately there is currently an absence of curative and preventative interventions for Alzheimer’s Disease (AD). Last year, Panza et al. reviewed the research on the links between vitamin D and AD. Low vitamin D levels have been associated with an accelerated decline in cognitive functions. They have also been associated with the development of chronic brain conditions such as AD and other dementias. As such, vitamin D is often thought of as a neurosteroid due to its effect on brain conditions. The authors believe more research is required to determine the effect of vitamin D supplementation on the prevention and/or treatment of AD.

Eating For Health And Longevity

Valter Longo et al. recently published a paper that examined research on the relationships between nutrition, health and longevity. Here are some of the main components of a longevity diet:

• mid to high carbohydrate intake (45-60%) – mostly non-refined
• fat intake (25-35%) – mostly plant-based
• low protein intake (10-15%) – mostly plant-based but includes regular consumption of peso-vegetarian-derived proteins. Low protein intake or normal protein intake (with high legume consumption) lowers the intake of amino acids such as methionine. This in turn lowers pro-aging substances such as GHR, IGF-1, insulin and TOR-S6K.
• over 65s need to be careful to avoid malnourishment and prevent frailty and diseases resulting from reduced muscle mass, reduced bone mass or low blood cell count.
• the largest gains in longevity come from diets rich in legumes, whole grains and nuts. With reduced amounts of red meat and processed meats
• a 12-13hr daily fasting period is key to reducing the insulin resistance that may have developed from a high calorie diet. The fasting window also helps decrease levels of IGF-1, lowers blood pressure, lowers total cholesterol and decreases inflammation.
• our daily food intake should be established by our body fat/lean body mass composition rather than generic pre-set calorie amounts.

Sweeteners Increase Cancer Risk

The use of artificial sweeteners by the food industry has become ubiquitous. They reduce the sugar content whilst still retaining the sweet pleasant taste. However, the safety of artificial sweeteners has been questioned, particularly regarding carcinogenicity.

Last month, Charlotte Debras et al. published the results of a study looking into the link between the consumption of sweeteners and cancer incidence. They followed a group of over 100,000 French adults for about 8 years.

The researchers found that “artificial sweeteners (especially aspartame and acesulfame-K) were associated with increased overall cancer risk (13%) for higher consumers compared to non-consumers. More specifically, aspartame was associated with increased breast (22%) and obesity-related (15%) cancer risks“.

We can conclude that reducing or eliminating our consumption of artificial sweeteners can play a significant role in cancer prevention.

Low Back Pain Could Affect How We Eat

A recent study by Lin et al. uncovered a relationship between longstanding low back pain and a preference for fat-rich foods. The authors found that the nucleus accumbens may be linked to the change in eating behaviour. The nucleus accumbens is a part of the brain that plays an important role in reward and pleasure processing. This could partly explain the high prevalence of obesity in people with longstanding pain.

Fat Injections For Plantar Fasciitis?

Beth Gusenoff et al. have just published the results of their study looking into the effects of fat cell injections for patients with plantar fasciitis. Plantar fasciitis is a common musculoskeletal condition that can lead to inflammation, degeneration and thickening of the plantar fascia. Patients usually present with heel pain during weight bearing activities. The symptoms are often worse in the morning and after periods of inactivity.

There are treatments such as arch-supporting insoles, night splints, soft tissue work, acupuncture, progressive stretching and strengthening, steroid injections, etc. But, the condition sometimes becomes chronic and lingers.

This was a very small study but it showed significant improvements in pain, function and structure of the plantar fascia after receiving perforating fat injections into the plantar fascia. It’s possible that the beneficial effects may be due to a healing response from the microtrauma caused by the needle. And/or the regenerative ability of stem cells and growth factors within fat.

The authors are planning large scale clinical trials to validate their results. It would be interesting for the authors to have a control group that is exposed to the needle microtrauma without the injection of fat cells. This would help determine whether it is the fat or the microtrauma that is responsible for the positive findings.

Covid-19 Research Update

Gu et al. (Nature) recently published a paper explaining the association between Covid-19 and inflammatory and blood coagulation disorders involving platelets and endothelial cells. This is probably why patients with cardiovascular risk factors such as diabetes, obesity and ageing have been particularly vulnerable to Covid-19.

Malas et al. have published a meta-analysis of 42 studies (8271 patients) looking into the association between thromboembolism (blood clots) and Covid-19. The overall venous thromboembolism rate was 21%, deep vein thrombosis (DVT) rate was 20% and pulmonary embolism rate was 13%. There was a positive correlation between disease severity and risk of blood clotting. The risk of thrombosis can affect any organ in the body. This has led to guidelines recommending the use of anticoagulants for Covid-19 patients, especially when hospitalised.

A Chinese cohort study published in The Lancet followed 1733 patients after they were discharged from hospital. They found that at 6 months after onset of Covid-19 symptoms most patients still had at least one symptom. The most common persisting problems were: fatigue or muscle weakness (63%), sleep difficulties (26%) and anxiety and/or depression (23%). Those that had been more severely ill had a high risk of pulmonary diffusion abnormalities and abnormal chest imaging. Persistent kidney dysfunction, diabetes and blood clotting disorders were also observed.