Why Sleep is Your Metabolic Superpower

We tend to think of sleep as rest – the way we replenish energy.  In truth, your sleeping hours are a highly productive repair shift, especially for your metabolism. 

Each night, your body resets blood sugar, clears metabolic waste, restores energy and even rewires memory. Consistently missing out on quality or quantity of sleep means less of that vital repair work gets done.

Most people notice tiredness after a bad night, but few realise the impact it has on their blood sugar, metabolism and even body composition.

So in our last article we explored melatonin’s role in brain repair, in this part 2 we look at how poor sleep throws off your body’s entire metabolic rhythm – from blood sugar to fat storage.

(When we talk about poor sleep, we mean getting less than seven hours a night, sleeping at irregular times, or waking often through the night – all of which disturb the deep, restorative phases your brain depends on.)

Sleep and insulin: two sides of the same coin

Deep, unbroken sleep keeps your cells sensitive to insulin, the hormone that allows glucose into cells to make energy. Cut the night short and this system falters. Just one poor night can reduce insulin sensitivity by about 25 per cent (1).

That means glucose lingers in the bloodstream (creating inflammation over time) while your brain cells are left hungry for fuel.

The result? Brain fog, irritability, and a body craving quick fixes – sugar, caffeine and refined carbohydrates. You’ll have felt this yourself: after a poor night’s sleep, you wake up wanting pastries or toast, not eggs and greens.

The “tired brain” that acts diabetic

When the brain can’t get enough glucose, it flips into survival mode.

Stress hormones like cortisol and adrenaline surge to keep you going, but they also spike blood sugar and wreck the next night’s sleep (hello, 4 a.m. wake-ups).

Brain scans show that after even a single sleepless night, glucose metabolism in the prefrontal cortex, the region responsible for focus and decision-making, drops sharply (2).

It’s a vicious cycle: sleep loss drives insulin resistance, which drives stress and sugar intake, which drives more sleep loss.

Poor Sleep Changes Your Metabolism

It’s easy to see how poor sleep doesn’t just fog your mind – it rewires your metabolism. Short sleep duration is now recognised as one of the strongest lifestyle predictors of weight gain, insulin resistance and type-2 diabetes – even when calorie intake stays the same,

Even a few nights of shortened sleep raise ghrelin, the hunger hormone, and suppress leptin, which signals fullness (7). The result is stronger cravings for quick-release carbs and sugary snacks, precisely the foods that destabilise blood sugar and accelerate insulin resistance. At the same time, sleep loss changes how your body stores fat: studies show it increases visceral fat, the deep belly fat that drives inflammation (8).

Over time, this mix – more hunger, higher insulin, greater inflammation – pushes many people toward weight gain, pre-diabetes and, eventually, cognitive decline.

So if you’re trying to lose weight or steady your energy, don’t forget about sleep.

High blood sugar, low cognition

Poor sleep raises blood sugar, and when glucose stays high, the brain pays the price.

Overtime poor sleep raises blood sugar, and when glucose stays high, the brain eventually pays the price. Chronically elevated HbA1c, measured in our DRIfT test, predicts faster cognitive decline and higher dementia risk. The same metabolic stress that drives weight gain and diabetes also drives neurodegeneration. That’s why people with insomnia or sleep apnoea are far more likely to develop both type-2 diabetes and Alzheimer’s (3, 4).That is why we cover both sleep and insulin management as a key part of our COGNITION 6-month brain upgrade programme (available to all FRIEND’s of Food for the Brain) – because protecting your brain is possible when you know what to focus on.

The night-shift hormones that matter

Melatonin isn’t just for sleep – it fine-tunes your body’s glucose rhythm and acts as a powereful antioxidant. When evening light suppresses it, next-morning blood sugar shoots higher (5).
Cortisol should fall overnight so insulin can do its work; if stress, late eating or light keeps it high, blood sugar stays stuck.
Growth hormone, released in deep sleep, repairs tissue and builds lean muscle, your natural blood-sugar buffer.

Together these hormones keep the night restorative and the brain calm. Disrupt them and the same chemistry that fuels diabetes starts fuelling Alzheimer’s (6).

Simple Ways to Turn Sleep into a Metabolic Superpower

Guard your 7–8 hours. Deep sleep is where metabolic reset happens.
Skip caffeine or alcohol late. Both fragment sleep and blunt insulin response.
Finish eating at least three hours before bed. Giving your body time to fast allows insulin to fall and encourages fat use for fuel overnight.
Start your day with light, not sugar. Early daylight synchronises your circadian rhythm, boosting morning cortisol naturally so you rely less on coffee and quick carbs.

Pair protein-rich, low-GL meals with consistent sleep. Balanced blood sugar by day supports stable melatonin and growth hormone at night, a feedback loop that keeps your metabolism working for you, not against you. Find 100+ delicious recipes here.https://foodforthebrain.org/uybcookapp/

Sleep as metabolic medicine

Sleep isn’t a luxury or a waste of time –  it’s your brain’s way of resetting and restoring the entire body. It shapes body composition, curbs cravings, steadies energy and supports the metabolism that powers your mind.

Takeaway: good sleep, like good nutrition, is prevention in action.
Want to dive deeper? Join us for the Sleep Solution Webinar with sleep scientist Greg Potter. Find out more here

Food for the Brain is a not-for-profit educational and research charity that offers a free Cognitive Function Test and assesses your Dementia Risk Index to be able to advise you on how to dementia-proof your diet and lifestyle.

By completing the Cognitive Function Test you are joining our grassroots research initiative to find out what really works for preventing cognitive decline. We share our ongoing research results with you to help you make brain-friendly choices.

Please support our research by becoming a Friend of Food for the Brain.

Reference:

Spiegel K et al. Impact of sleep debt on metabolic and endocrine function. Lancet. 1999;354(9188):1435–9.

Benedict C et al. Acute sleep deprivation reduces energy expenditure and brain glucose metabolism. Sleep. 2012;35(7):981–8.

Yaffe K et al. Sleep duration and risk of type 2 diabetes: a meta-analysis. Diabetes Care. 2015;38(9):1633–40.

Sabia S et al. Association of sleep duration in middle and old age with dementia incidence. Nat Commun. 2021;12:2289.

Gooley JJ et al. Exposure to room light before bedtime suppresses melatonin onset and shortens its duration. J Clin Endocrinol Metab. 2011;96(3):E463–72.

Musiek ES, Holtzman DM. Mechanisms linking circadian clocks, sleep, and neurodegeneration. Science. 2016;354(6315):1004–8.

Spiegel K et al. Brief sleep curtailment decreases leptin, increases ghrelin, and causes increased hunger and appetite. Ann Intern Med. 2004;141(11):846–50.

Nedeltcheva AV et al. Insufficient sleep undermines dietary efforts to reduce adiposity. Ann Intern Med. 2010;153(7):435–41.

Melatonin: The Brain’s Night-Time Antioxidant

This night-time molecule is also one of the brain’s most powerful protectors – your night-time antioxidant – working while you rest, to defend neurons, restore energy and preserve clear thinking. Melatonin helps your brain clean up daily oxidative damage, regulate mood, and protect memory networks from ageing.

When levels drop – through stress, light exposure, age or caffeine – you don’t just lose sleep; you lose part of your brain’s natural repair system.

The Brain’s Nightly Repair Shift

Every night, while you rest, your brain goes to work. Waste is cleared away, cells are repaired, and antioxidants are replenished.

At the heart of this clean-up crew is melatonin, made in the pineal gland and the master conductor of your brain’s nocturnal activity.

It doesn’t just promote sleep; it powers the production of glutathione, the body and brain’s chief antioxidant and cellular shield. When melatonin levels fall, oxidative stress rises – accelerating neuronal ageing and the build-up of damaging amyloid and tau proteins (1, 2). Why? Melatonin normally switches on the brain’s own antioxidant defences, recycling glutathione and neutralising free radicals inside mitochondria. Without enough melatonin, these reactive molecules (like amyloid and tau proteins) accumulate, inflaming brain tissue and allowing toxic proteins to clump together.

In studies (2), restoring melatonin reduced oxidative damage and slowed amyloid formation – a reminder that good sleep truly is brain repair in action.

Want to know what your current glutathione status is? Order your test here to find out

Light At Night Steals Your Brain’s Protection

Here’s the catch: melatonin only comes out when it’s dark.

Even modest evening light – the glow of your phone, TV, bedside lamp or standby light – can switch off its release (7).

That’s because the light-sensitive cells in your eyes, send a “daytime” signal to the brain’s master clock in the suprachiasmatic nucleus (a tiny region in the hypothalamus that controls your body’s sleep-wake rhythm) instantly halting melatonin production.

In clinical studies, exposure to ordinary indoor light before bedtime suppressed melatonin by up to 85 per cent and shortened its duration by several hours (7).

That’s why your late-night scroll or TV binge can leave you foggy and flat the next morning. 

To support melatonin, you want to create a dark place to sleep. No lights on, heavy curtains, no street lamps. Using eye masks and utilising blue-light blocking glasses, software or filters can also be helpful if you know you are going to be on screens in the evening. You can even get special bulbs for bedside lamps or special lighting solutions for the bathroom for nighttime toilet trips.

Light is a powerful data input into the brain – so be mindful and protect yourself where practical and possible. 

Age, Stress And Hormones Flatten The Rhythm

As time goes by, your natural melatonin rhythm starts to fade – by mid-life, your night-time levels can fall by half (3).

It’s one of many reasons why people can start waking up at night, struggle to drift off, or feel less refreshed after sleep.

For women, the hormonal rollercoaster of perimenopause makes things even trickier: falling oestrogen and progesterone throw the body clock off balance, making deep sleep harder just when the brain needs it most (5). (Learn more about how to support women’s hormones and brain health here.)

Melatonin levels don’t just impact sleep; studies show that lower melatonin is linked with poorer memory, mood dips and faster cognitive ageing (4). While melatonin is impacted by ageing, the good news is that it can be supported and restored.

Coffee vs. Melatonin – When Caffeine Steals Your Sleep Hormone

Caffeine doesn’t just keep you awake – it directly interferes with melatonin’s nightly rise.
Even a single espresso six hours before bed can delay melatonin release by up to 40 minutes and reduce total melatonin production by as much as 20% (9). (And don’t forget black and green tea and most energy drinks contain caffeine too.)

That’s because caffeine blocks adenosine receptors – the same system that tells the pineal gland it’s time for darkness and rest. When that signal is muted, the body’s internal clock (the suprachiasmatic nucleus) misreads the time and keeps you in ‘day-mode’ far longer than intended.

Avoid coffee (and other caffeine sources) after 12 p.m., especially if you have sleep or mood issues.
Choose herbal or decaf alternatives after lunch. If you’re sensitive, even morning caffeine can blunt night-time melatonin, so experiment with caffeine-free days and observe your sleep quality.

Melatonin and Mitochondria: Your Inner Night-Time Antioxidant Factory

Here’s where melatonin gets even more fascinating. It isn’t just released from the pineal gland at night, your brain cells actually produce it inside their mitochondria, the tiny engines that create energy (ATP) and power every thought and memory (8).

This is clever biology: the very place where energy is made – and where most oxidative stress occurs – also makes its own night-time antioxidant. Melatonin acts locally in the cell, mopping up the free radicals created as mitochondria burn fuel through the day, keeping these fragile energy factories running smoothly (1).

It doesn’t function only as a sleep hormone, made only in the pineal gland – it’s also made throughout your brain (and body’s) energy-producing mitochondria, where it acts as a built-in night-time antioxidant to protect them from damage.

This local production is what keeps your neurons energised and resilient – and why good, deep sleep is essential for restoring brain power and mental clarity. (And why disrupted or shallow sleep can leave you foggy the next morning!)Want more insight into how to support your brain through quality sleep? Join our next live webinar with our expert Sleep Scientist here.

How To Restore Your Natural Rhythm

While short-term melatonin supplements (0.5–3 mg) can improve sleep onset and quality in older adults (6) and can be bought in North America or prescribed in the UK, the goal is to rebuild the body’s own rhythm:

Dark evenings, bright mornings – dim lights, avoid screens, use blue-light blocking technology, glasses and filters an hour before bed; get natural light soon after waking.
Avoid caffeine after 12 pm or if sleep is a real struggle – remove altogether, and see how it impacts your sleep.
Tryptophan-rich foods – turkey, oats, eggs and sunflower seeds support serotonin-to-melatonin conversion (with B6 and magnesium).
Keep bedrooms cool and quiet – a small temperature drop signals melatonin release.
Check in with your antioxidant status with the DRIfT test here.

Melatonin: Protecting Your Brain’s Night-time Antioxidant Rhythm

Melatonin is the nightly molecule that lets the brain rest, reset and renew itself.

Protecting your melatonin rhythm may be one of the simplest, most powerful preventative steps you can take to protect your memory.

To learn more and take action:

Join the Sleep Solution Webinar with Sleep Scientist Greg Potter here
Get a free assessment of your overall brain health and cognitive function today with our free, validated Cognitive Function test here
Test your current glutathione status with the DRIfT 5 in 1 at home blood test – find out more here

Food for the Brain is a not-for-profit educational and research charity that offers a free Cognitive Function Test and assesses your Dementia Risk Index to be able to advise you on how to dementia-proof your diet and lifestyle.

By completing the Cognitive Function Test you are joining our grassroots research initiative to find out what really works for preventing cognitive decline. We share our ongoing research results with you to help you make brain-friendly choices.

Please support our research by becoming a Friend of Food for the Brain.

Reference:

Reiter RJ et al. Melatonin as an antioxidant: under promises but over delivers. J Pineal Res. 2016;61(3):253–78.

Cardinali DP et al. Melatonin reduces oxidative damage and amyloid pathology in Alzheimer transgenic mice. J Pineal Res. 2013;55(4):427–37.

Waldhauser F et al. Age-related changes in melatonin levels. J Clin Endocrinol Metab. 1988;66(3):648–52.

Wu YH et al. Sleep, melatonin and the aging brain. J Pineal Res. 2005;38(3):145–52.

Baker FC, Driver HS. Circadian rhythms, sleep and the menstrual cycle in women. Sleep Med. 2007;8(6):613–22.

Ferracioli-Oda E et al. Meta-analysis: efficacy of melatonin for primary sleep disorders. PLoS One. 2013;8(5):e63773.

Gooley JJ et al. Exposure to room light before bedtime suppresses melatonin onset and shortens its duration. J Clin Endocrinol Metab. 2011;96(3):E463–72.

Suofu Y et al. Mitochondrial synthesis of melatonin enhances neuroprotection. Proc Natl Acad Sci USA. 2017;114(32):E7997–8006.

Burke TM et al. Caffeine effects on the circadian melatonin rhythm: a controlled trial. J Clin Sleep Med. 2015;11(8):893–900.

By Patrick Holford

What does any animal, perhaps your dog, do after exercising or going for a walk?

Sleep.

Sleep is how the brain recovers. There is now overwhelming evidence that sleep is a ‘brain essential’ and just like Goldilocks, it seems we need just the right amount. Getting too much, or too little, increases our risk for cognitive decline.

The optimal amount of sleep for brain health appears to be a total of seven hours. This does not necessarily need to be in one uninterrupted stretch – a study found that napping after physical activity can reduce the risk of cognitive impairment (1).

However, those consistently getting less than seven hours of sleep may be doubling their risk of age-related cognitive decline (2). A UK study of Whitehall civil servants, which began in the 1980s, found that persistent short sleep at ages 50, 60, and 70 was associated with a 30% increased risk of dementia (3). Sleep loss does not just increase long-term dementia risk – it also reduces empathy, increases negative emotions, and impairs next-day functioning (4).

Why Sleep Is Essential to Brain Health?

Think of sleep as the brain’s housekeeper. During sleep, circulation of blood and cerebrospinal fluid improves, helping to clear out waste products from brain metabolism (5). These include harmful oxidants and amyloid protein, the latter linked to Alzheimer’s and brain inflammation – which can begin accumulating after just one night of poor sleep (6).

One key agent in this nightly brain cleanse is melatonin. As night falls, our brains convert serotonin into melatonin, primarily in the pineal gland – referred to by Descartes as the seat of the soul, and known in yoga as the ‘third eye’ chakra.

Sensitive to light via receptors behind the eyes, the pineal gland is the only endocrine organ in direct contact with the external world. Darkness triggers melatonin production, while exposure to light – including screen use before bed – suppresses it.

Melatonin helps keep us in sync with the circadian cycle. Some frequent flyers even use melatonin supplements to overcome jet lag and adjust their sleep rhythms more easily (7).

More than just a sleep aid, melatonin acts as a powerful antioxidant – disarming damaging oxidants, restoring mitochondrial energy production, and acting as an anti-inflammatory. It has been used to support recovery in cancer, COVID-19, and cardiovascular conditions (8,9). Reduced brain melatonin levels and circadian disruption are also observed in individuals with cognitive decline.

Why Dreaming Matters?

Sleep isn’t just for rest – it’s a deeply active process. About 30 minutes after falling asleep, we enter deep sleep, marked by slower breathing, a reduced heart rate, and lower blood pressure. This phase restores and repairs bodily tissues. About 90 minutes in, we shift into REM (rapid eye movement) sleep – where most dreaming occurs.

REM sleep is critical for brain health. Each night, we cycle between deep, light, and REM sleep three to five times, with REM ideally making up about 25% of total sleep.

REM and deep sleep phases also see increased production of growth hormone, which supports tissue repair. Meanwhile, melatonin helps clear metabolic waste. However, under stress, cortisol levels rise and suppress REM sleep and growth hormone production, reducing the brain’s ability to recover. Sleep-deprived individuals tend to experience more REM when they finally do sleep, suggesting REM plays a key role in emotional processing.

One theory suggests that dreams help us metabolise suppressed emotions – fear, anger, sadness – stored during our busy days. If you have a vivid, emotional dream, it may be worth tracing it back to unresolved feelings from the previous day.

How Chronic Stress Disrupts Sleep and Brain Function?

Chronic or intense stress – such as bereavement, illness, or financial strain – has been shown to increase the risk of cognitive decline and dementia (10). However, good sleep can help process a stressful day.

The perception of control matters, too. Studies show that high job demands combined with low control are strongly linked to an increased risk of depression and cognitive impairment (11). Examples might include caregiving for a loved one with dementia while navigating health services, or working in a high-stress job without the resources to make meaningful changes.

Your Brain on Cortisol: The Hippocampus Feedback Loop

Two hormones mediate stress: adrenaline (short-acting) and cortisol (longer-acting). Adrenaline prepares you to act quickly – it’s the fight-or-flight hormone. Cortisol helps regulate energy and alertness throughout the day.

In the morning, cortisol naturally rises to get us going. It should fall in the evening to support sleep. But chronic stress disrupts this rhythm. If cortisol stays high at night, sleep is disturbed. If it’s too low in the morning, you may feel foggy and reach for caffeine.

Excess cortisol impairs memory, slows thinking, lowers social functioning, and raises the risk of dementia (12). What’s happening in the brain is that cortisol overstimulates the hippocampus, which is responsible for memory and emotional regulation. With prolonged stress, this feedback loop fails – the hippocampus shrinks, and cortisol levels remain elevated, accelerating brain ageing.

Short-Term Relief, Long-Term Harm: Sugar and Alcohol as Stress Crutches

Oscar Ichazo described how we reach for compensations under stress. Unfortunately, many – like alcohol and sugar – backfire.

Alcohol temporarily boosts GABA, calming the nervous system and reducing adrenaline. But the effect is short-lived. Drinking too much reduces GABA receptor sensitivity the next day, leaving us more anxious. In the long term, alcohol is neurotoxic and increases dementia risk (12). It also disrupts sleep architecture, impairing the brain’s ability to repair itself.

Sugar triggers dopamine and activates the brain’s reward circuits, making us crave more. It also spikes the adrenal system, amplifying stress and cortisol levels (13). Fats and proteins do not have this effect – this is unique to sugar.

So, when we use sugar or alcohol to manage stress, we often wake up feeling more anxious and foggy. This leads us to reach for caffeine and more sugar, which spikes cortisol again, leaving us even more depleted by evening – creating a cycle of stress, poor sleep, and accelerated brain ageing.

Simple Ways to Break the Cycle

The good news? You can reverse this pattern. Start here:

Become a FRIEND and get access to your personalised COGNITION® programme which which includes:
– A whole module dedicated to sleep and calm
– Another focused on helping you reduce sugar
– Plus monthly live group coaching to help you stay focused and on track
Prioritise seven hours of quality sleep each night.
Identify and reduce common stress triggers.
Be mindful of alcohol and sugar intake.
Find positive outlets: yoga, walking, journaling, a good book – like Upgrade Your Brain.

–

Thank you for reading!
Food for the Brain is a non-for-profit educational and research charity that offers a free Cognitive Function Test and assesses your Dementia Risk Index to be able to advise you on how to dementia-proof your diet and lifestyle.

By completing the Cognitive Function Test you are joining our grassroots research initiative to find out what really works for preventing cognitive decline. We share our ongoing research results with you to help you make brain-friendly choices.

Please support our research by becoming a Friend of Food for the Brain.

———

References:

¹ Qian YX, Ma QH, Sun HP, Xu Y, Pan CW. Combined effect of three common lifestyle factors on cognitive impairment among older Chinese adults: a community-based, cross-sectional survey. Psychogeriatrics. 2020 Nov;20(6):844-849. doi: 10.1111/psyg.12604. Epub 2020 Aug 31. PMID: 32869429.

² Bubu OM, Brannick M, Mortimer J, Umasabor-Bubu O, Sebastião YV, Wen Y, Schwartz S, Borenstein AR, Wu Y, Morgan D, Anderson WM. Sleep, Cognitive impairment, and Alzheimer’s disease: A Systematic Review and Meta-Analysis. Sleep. 2017 Jan 1;40(1). doi: 10.1093/sleep/zsw032. PMID: 28364458.

³ Sabia S, Fayosse A, Dumurgier J, van Hees VT, Paquet C, Sommerlad A, Kivimäki M, Dugravot A, Singh-Manoux A. Association of sleep duration in middle and old age with incidence of dementia. Nat Commun. 2021 Apr 20;12(1):2289. doi: 10.1038/s41467-021-22354-2. PMID: 33879784; PMCID: PMC8058039.

⁴ Krause AJ, Simon EB, Mander BA, Greer SM, Saletin JM, Goldstein-Piekarski AN, Walker MP. The sleep-deprived human brain. Nat Rev Neurosci. 2017 Jul;18(7):404-418. doi: 10.1038/nrn.2017.55. Epub 2017 May 18. PMID: 28515433; PMCID: PMC6143346.

5⁶ Xie L, Kang H, Xu Q, Chen MJ, Liao Y, Thiyagarajan M, O’Donnell J, Christensen DJ, Nicholson C, Iliff JJ, Takano T, Deane R, Nedergaard M. Sleep drives metabolite clearance from the adult brain. Science. 2013 Oct 18;342(6156):373-7. doi: 10.1126/science.1241224. PMID: 24136970; PMCID: PMC3880190.

⁶ Shokri-Kojori E, Wang GJ, Wiers CE, Demiral SB, Guo M, Kim SW, Lindgren E, Ramirez V, Zehra A, Freeman C, Miller G, Manza P, Srivastava T, De Santi S, Tomasi D, Benveniste H, Volkow ND. β-Amyloid accumulation in the human brain after one night of sleep deprivation. Proc Natl Acad Sci U S A. 2018 Apr 24;115(17):4483-4488. doi: 10.1073/pnas.1721694115. Epub 2018 Apr 9. PMID: 29632177; PMCID: PMC5924922.

⁷ Herxheimer A, Petrie KJ. Melatonin for the prevention and treatment of jet lag. Cochrane Database Syst Rev. 2002;(2):CD001520. doi: 10.1002/14651858.CD001520. PMID: 12076414.

⁸ Keithahn C, Lerchl A. 5-hydroxytryptophan is a more potent in vitro hydroxyl radical scavenger than melatonin or vitamin C. J Pineal Res. 2005 Jan;38(1):62-6. doi: 10.1111/j.1600-079X.2004.00177.x. PMID: 15617538.

⁹ Chitimus DM, Popescu MR, Voiculescu SE, Panaitescu AM, Pavel B, Zagrean L, Zagrean AM. Melatonin’s Impact on Antioxidative and Anti-Inflammatory Reprogramming in Homeostasis and Disease. Biomolecules. 2020 Aug 20;10(9):1211. doi: 10.3390/biom10091211. PMID: 32825327; PMCID: PMC7563541; regarding covid see also Tan DX, Reiter RJ. Mechanisms and clinical evidence to support melatonin’s use in severe COVID-19 patients to lower mortality. Life Sci. 2022 Apr 1;294:120368. doi: 10.1016/j.lfs.2022.120368. Epub 2022 Jan 30. PMID: 35108568; PMCID: PMC8800937.; see also Begum R, Mamun-Or-Rashid ANM, Lucy TT, Pramanik MK, Sil BK, Mukerjee N, Tagde P, Yagi M, Yonei Y. Potential Therapeutic Approach of Melatonin against Omicron and Some Other Variants of SARS-CoV-2. Molecules. 2022 Oct 16;27(20):6934. doi: 10.3390/molecules27206934. PMID: 36296527; PMCID: PMC9609612.; regarding cancer see Reiter RJ, Rosales-Corral SA, Tan DX, Acuna-Castroviejo D, Qin L, Yang SF, Xu K. Melatonin, a Full Service Anti-Cancer Agent: Inhibition of Initiation, Progression and Metastasis. Int J Mol Sci. 2017 Apr 17;18(4):843. doi: 10.3390/ijms18040843. PMID: 28420185; PMCID: PMC5412427.

¹0 Franks KH, Bransby L, Saling MM, Pase MP. Association of Stress with Risk of Dementia and Mild Cognitive Impairment: A Systematic Review and Meta-Analysis. J Alzheimers Dis. 2021;82(4):1573-1590. doi: 10.3233/JAD-210094. PMID: 34366334.

¹1 Wang HX, Wahlberg M, Karp A, Winblad B, Fratiglioni L. Psychosocial stress at work is associated with increased dementia risk in late life. Alzheimers Dement. 2012;8(2):114-20. doi: 10.1016/j.jalz.2011.03.001. PMID: 22404853; see also Gonzalez-Mulé, E., & Cockburn, B. S. (2021). This job is (literally) killing me: A moderated-mediated model linking work characteristics to mortality. Journal of Applied Psychology, 106(1), 140–151. https://doi.org/10.1037/apl0000501; see also Gonzalez-Mulé E, Kim MM, Ryu JW. A meta-analytic test of multiplicative and additive models of job demands, resources, and stress. J Appl Psychol. 2021 Sep;106(9):1391-1411. doi: 10.1037/apl0000840. Epub 2020 Sep 21. PMID: 32955269.

¹2 Ouanes S, Popp J. High Cortisol and the Risk of Dementia and Alzheimer’s Disease: A Review of the Literature. Front Aging Neurosci. 2019 Mar 1;11:43. doi: 10.3389/fnagi.2019.00043. PMID: 30881301; PMCID: PMC6405479.¹3 Gonzalez-Bono E, Rohleder N, Hellhammer DH, Salvador A, Kirschbaum C. Glucose but not protein or fat load amplifies the cortisol response to psychosocial stress. Horm Behav. 2002 May;41(3):328-33. doi: 10.1006/hbeh.2002.1766. PMID: 11971667.