The science of beauty sleep
Best practices for deep, restorative nights, and what your body rebuilds while you sleep. Four parts, from the science of the night to habits you can start tomorrow. Great mornings start the night before.
It can look like nothing is happening. In reality, the night is one of the busiest shifts your body works: the brain sorts and clears, hormones are recalibrated, tissues are repaired, and the gut resets. How you live your day decides how well that shift goes. This guide brings together the physiology of sleep and the practical habits that support it, drawing on two of the most widely read scientists in the field, summarised in our own words.
Professor of Neuroscience and Psychology at the University of California, Berkeley, founder-director of its Center for Human Sleep Science, and author of Why We Sleep (2017). His central argument: sleep is not a luxury to trade away, but the foundation that diet and exercise stand on.
Associate Professor of Neurobiology and Ophthalmology at Stanford University School of Medicine, host of the Huberman Lab podcast and author of Protocols (2025). His first rule: light at the right time, especially daylight soon after waking, is the strongest signal you can give your body clock.
WITH ME NUTRITION is not affiliated with, or endorsed by, the authors cited. Their work is referenced for education only.
Sleep moves in cycles of roughly 90 minutes. Each cycle passes through light sleep, deep (slow-wave) sleep and REM sleep, but the mix changes as the night goes on.
Long stretches of slow-wave sleep. This is when most growth hormone is released (Van Cauter 2000) and when physical restoration is strongest. Going to bed very late cuts into this window.
REM periods get longer toward morning. Walker describes REM as a kind of overnight therapy for emotional processing (Walker and van der Helm 2009). An early alarm or alcohol trims it first.
Illustrative curves based on typical adult patterns; individual timing varies with chronotype.
During sleep, the space between brain cells widens by about 60 percent, letting cerebrospinal fluid flush out metabolic waste that builds up while you are awake: the glymphatic system (Xie 2013).
Pulses of growth hormone in deep sleep drive protein synthesis in muscle, bone and skin. Amino acids such as glycine, the most abundant amino acid in collagen, are among the building blocks used.
Deep sleep moves the day’s learning into long-term storage; REM integrates it and softens the emotional charge of difficult experiences (Walker and van der Helm 2009).
Cortisol is held low in the first half of the night; appetite hormones (leptin and ghrelin) and insulin sensitivity are recalibrated. Even one short night pushes next-evening cortisol up (Leproult 1997).
Immune cells use the night to communicate through signalling molecules (cytokines) and to consolidate immune memory.
Overnight, cells step up housekeeping: repairing DNA, recycling damaged components (autophagy) and renewing antioxidant defences.
Walker’s point: there is hardly a system in the body that is not improved by good sleep, or harmed when sleep is short. Paraphrased from Why We Sleep (2017).
Cortisol is not the enemy. It follows a daily rhythm: lowest in the first half of the night, rising in the early morning hours and peaking shortly after waking to get you up and going. Trouble starts when that curve is flattened, for example by short sleep, late stress, alcohol or bright light late at night.
At high levels, cortisol also acts on the same kidney receptors as aldosterone, the hormone that tells the body to hold on to sodium, and with it water. A night in which cortisol stays elevated tips the balance toward retention. Lying flat for hours also lets fluid redistribute toward the face. When the night is calm, cortisol low and sleep deep, the lymphatic system has hours to move that fluid away, which is part of why you wake up looking less puffy. Late salty meals and evening alcohol leave your face puffier in the morning.
When the same people were photographed after normal sleep and after 31 hours awake, raters saw more swollen eyes, darker under-eye circles, droopier eyelids, paler skin and more fine lines after sleep loss (Sundelin 2013). In another study, sleep-deprived faces were rated less healthy and less attractive (Axelsson 2010).
Dim lights and screens off in the last hour.
Less salt and no alcohol late in the evening.
Morning daylight sets a strong, healthy peak.
Skin, hair and the way we hold water are closely linked to hormones and sleep. For women, monthly hormonal shifts add another layer.
Compared with good sleepers, women who slept poorly showed more signs of intrinsic skin ageing and recovered more slowly when their skin barrier was disrupted (Oyetakin-White 2015).
Chronically high glucocorticoids slow collagen production and thin the skin over time. A night spent in deep sleep with low cortisol and a growth-hormone pulse gives the opposite conditions: a building phase.
Pallor and dark circles after a bad night come from changes in blood flow and fluid around the eyes (Sundelin 2013). A regular rhythm keeps both steadier.
In the second half of the cycle, progesterone raises body temperature, and both oestrogen and progesterone can increase water retention. Keep the bedroom a little cooler then, and be extra consistent with light, caffeine and dinner timing.
They are built from protein and depend on minerals such as zinc. Zinc contributes to the maintenance of normal skin, hair and nails (EU-authorised health claim).
A large share of the body’s immune tissue lines the gut, and your gut bacteria follow a daily rhythm just like you do.
The composition and activity of gut bacteria rise and fall over 24 hours, driven by when we eat. Erratic schedules and jet lag disrupt this rhythm (Thaiss 2014).
Once digestion is finished, the small intestine runs cleaning waves (the migrating motor complex) that sweep leftovers onward. They only start when you are not eating, which is one reason a 2 to 3 hour gap between dinner and bed matters.
The cells lining the gut are replaced every few days, one of the fastest renewal rates in the body. That rebuilding needs amino acids, zinc and B vitamins available in the bloodstream.
The gut contains far more melatonin than the pineal gland (at least 400 times more by some estimates; Bubenik 2002), and there it supports the gut’s own rhythm.
The idea in one line: if you give the gut a quiet night, a fasting window and the right nutrients, it uses the dark hours to rebuild. The gut–brain axis runs both ways: poor sleep alters gut bacteria, and gut health influences stress and sleep signals.
Cortisol peaks 30 to 45 minutes after waking, stays high through the morning and slowly declines toward its lowest point around midnight. Melatonin is its mirror image. Plan your day along that curve: demanding tasks on the way up, calmer ones on the way down.
Daylight, a protein-rich breakfast, movement and focused work. A strong peak sets up a deep evening trough.
Put high-intensity training in the first part of the day, while cortisol and alertness are naturally high. Keep evenings for walks, mobility or yoga.
Late HIIT, big late dinners, late caffeine and bright screens keep cortisol up and push melatonin back.
Our coaching principle: if mornings and afternoons are active enough, evenings become restful on their own. Illustrative curves for someone waking around 07:00.
After light, food is one of the strongest signals your body clock reads. The same meal is handled differently at 08:00 and at 22:00: insulin sensitivity is higher in the morning and falls through the evening.
Protein (about 30 to 40 g), healthy fats, complex carbohydrates and fibre. Eggs, Greek yoghurt, fish, tofu, oats, wholegrain bread, seeds, berries.
Tryptophan from protein is the raw material for serotonin by day and melatonin by night. Students who ate a protein-rich breakfast, got daylight and used warm, dim light at night had higher evening melatonin and better sleep (Wada 2013).
Largest meals early, smaller ones later. With the same total calories, women who ate a large breakfast and a small dinner lost more weight and had better blood sugar and appetite control than those who did the reverse (Jakubowicz 2013).
Higher fibre intake was linked to more deep sleep, while more sugar and saturated fat were linked to lighter, more broken sleep (St-Onge 2016).
Finish a lighter dinner 2 to 3 hours before bed. An empty gut lets core temperature fall, avoids reflux and frees the night for the gut’s cleaning waves and lining repair.
A meal with complex carbohydrates 1 to 3 hours before intense training (oats, rice, potatoes, fruit) tops up glycogen, so you can train harder and with more power.
After the session, carbohydrates restore glycogen and protein supplies amino acids for muscle repair (Kerksick 2017).
For people who train, about 1.6 g per kg of body weight per day is where the benefits for muscle start to level off (Morton 2018). Spread it across 3 to 5 meals of roughly 0.4 g/kg each (Schoenfeld and Aragon 2018); 20 g every 3 hours worked better than fewer, larger servings or more frequent, smaller ones (Areta 2013).
Oestrogen and progesterone are made from cholesterol. Very low-fat diets can affect hormonal balance and the absorption of vitamins A, D, E and K. Choose olive oil, avocado, nuts, seeds and oily fish.
Especially around sweaty sessions. Front-load fluids earlier in the day so you are not drinking large amounts before bed.
Training is the stimulus, food provides the materials, and deep sleep, with its growth-hormone pulse, is when the rebuilding happens.
The principles behind our coaching, each with the studies that support it (full references at the end of this guide).
Total intake and enough protein matter far more than any single superfood or timing trick. (Hall et al. 2015; Morton et al. 2018)
The best plan is the one you can follow most days. No food is forbidden; most of your intake comes from whole foods. (Gardner et al. 2018; Conlin et al. 2021)
Moderate, temporary deficits with maintenance phases in between, and a gradual increase in food (reverse dieting) after a diet ends. (Tomiyama et al. 2010; Trexler et al. 2014; Byrne et al. 2018)
Strength training plus protein protects metabolism, bone and body composition as we age. (Cava et al. 2017; Morton et al. 2018)
Weight, energy, sleep and performance are judged over weeks, not by one morning on the scale. (Burke et al. 2011; Hall et al. 2011)
For the body, a severe calorie deficit is not a diet. It is a stress signal, and stress has a hormone.
Women on a 1,200 kcal-a-day diet for three weeks produced more cortisol, and simply counting calories increased perceived stress (Tomiyama 2010).
Higher evening cortisol and lower blood sugar at night make it harder to fall asleep and easier to wake at 3 to 4 a.m.
When intake does not cover training and daily life, the body cuts back on non-essential work: menstrual cycle, bone building, immunity, muscle repair, mood and sleep. This is known as relative energy deficiency in sport (Mountjoy 2018).
Too little protein, healthy fats, fibre, vegetables and fruit means fewer amino acids, omega-3s and micronutrients for repair, and lighter sleep (St-Onge 2016).
Dull skin, brittle nails and hair shedding a few months after a crash diet are common complaints. Hair and nails are among the first non-essential tissues to lose resources.
Long, aggressive deficits lower energy expenditure and increase hunger, making results harder to keep.
Eat enough to recover first. If fat loss is the goal, keep the deficit moderate, temporary and protein-rich.
of the body’s serotonin is made in the gut, by enterochromaffin cells whose output is regulated by gut bacteria (Yano 2015). Gut serotonin steers digestion and motility and talks to the brain through the vagus nerve.
of the immune system sits in and around the gut wall (Vighi 2008), constantly deciding what is food, what is friendly bacteria and what is a threat.
The gut lining is a single layer of cells renewed every few days. A healthy lining with intact villi absorbs the nutrients you eat; a stressed one absorbs less, even from a good diet.
Protein (amino acids such as glutamine and glycine), zinc, vitamin A and B vitamins. Zinc contributes to the normal function of the immune system (EU-authorised claim).
Gut bacteria ferment fibre into short-chain fatty acids such as butyrate, the main fuel of colon cells.
People eating 30 or more different plants a week had more diverse gut bacteria (McDonald 2018). A diet rich in fermented foods increased microbiome diversity and lowered inflammatory markers (Wastyk 2021).
Low intake of protein, fibre and plant foods, chronic stress, poor sleep and alcohol can thin the protective mucus layer and loosen the tight junctions between gut cells. When the barrier is looser, more undigested food fragments and bacterial components reach the immune cells underneath, and the immune system stays on higher alert.
Increased intestinal permeability has been associated with several autoimmune conditions, and is being investigated as one possible contributing factor (Fasano 2012).
The gut is where the immune system learns tolerance to food; disruptions in that balance are linked with food allergy (Vighi 2008).
Mast cells in the gut wall release histamine. Their overactivation is studied in food intolerances and sensitive-gut symptoms.
Enough protein, 30 or more plants a week, fermented foods, omega-3 fats, colourful polyphenols, adequate zinc, deep regular sleep and stress management.
These are associations from active research, not proof of cause. Allergies, intolerances and autoimmune conditions need assessment by a doctor.
5 to 10 minutes outdoors on a clear morning, about 15 when cloudy, up to 30 on grey days. No sunglasses and not through a window; regular glasses and contact lenses are fine. This sets a healthy morning cortisol peak and starts the countdown to evening melatonin.
Hydrate on waking. If you get an afternoon slump even when you sleep well, try your first coffee 30 to 90 minutes after waking. If you train first thing and want caffeine, have it.
Caffeine blocks adenosine, the sleep-pressure molecule, for many hours. Have your last one 8 to 10 hours before bed (12 if you are sensitive), which for most people means none after 14:00. Even if you can fall asleep after coffee, your deep sleep will be lighter.
Schedule high-intensity training in the first part of the day, with your natural cortisol peak. Save evenings for gentle stretching, walks or yoga.
10 to 15 minutes outside as the sun gets low helps anchor your clock and partly buffers the effect of evening screens.
Pair carbohydrates with protein, fibre and vegetables, and take a 10-minute walk afterwards.
Use warm, low and indirect lighting: lamps placed low, warm-white or amber bulbs, even candles. Avoid bright overhead light.
Phones and laptops combine bright light with stimulation. Reading on a light-emitting e-reader before bed delayed sleep and melatonin compared with a printed book (Chang 2015). If you must use a screen, turn the brightness down and use the night or red filter. Keep the phone on silent or in another room and use a simple alarm clock.
Protein and vegetables, moderate carbs. Aim to go to bed with an empty digestive tract; a full stomach raises body temperature and keeps digestion working.
It helps you drift off but fragments the night and suppresses REM and deep sleep, even after one or two drinks. If you drink, aim to stop about 8 hours before sleep, and drink extra water before bed and on waking.
The body needs to drop its core temperature to fall asleep. Keep the bedroom at 18 to 20 °C (maximum 21). A warm shower or bath in the evening draws heat to the hands and feet so the core cools faster. Let your feet stick out from the duvet, and skip socks unless you are cold.
If you can, let the room warm by 1 to 2 °C in the last hour or two of the night, or keep socks or a hoodie nearby for early-morning wake-ups.
Aim for great sleep about 90 percent of nights. The other 10 percent is for celebrations and late dinners, with no guilt and no stress.
For a week, go to bed when you first feel sleepy, without screens, and note when you naturally wake rested. Then keep bed and wake times within 30 minutes, 6 to 7 nights a week.
Skip counting sheep. Mentally walk a familiar route in detail, there and back. Or, with eyes closed, slowly look left and right, up and down and in circles, then take a deep breath and a long exhale, 1 to 3 times.
Non-sleep deep rest (NSDR, yoga nidra): 10 to 30 minutes lying down, eyes closed, long exhales, a guided body scan. Useful after a poor night, as an afternoon reset, or when you wake at night and can’t drift off.
15 to 20 minutes with an alarm boosts focus. Never longer than 90 minutes, and not late in the day. If you struggle to sleep at night, skip naps.
Sleep in by 1 to 2 hours at most, get morning light anyway, take a 20-minute nap if needed and go to bed at your usual time. Don’t push caffeine later.
Flying east: for 2 days beforehand, wake 30 to 45 minutes earlier and get bright light, caffeine and movement early. Flying west: shift all three 30 to 45 minutes later. On arrival, eat at local meal times, train in the local morning and keep evenings dim. For trips under two days, stay close to your home schedule.
An example for someone who sleeps around 22:30. Shift every time by the same amount to match your own chronotype.
Water, then 5 to 10 minutes of daylight (15 to 30 if cloudy).
Protein, healthy fats, complex carbs, fibre.
With the cortisol peak; coffee before if you like.
Protein and complex carbs to restore glycogen.
Caffeine-free 8 to 10 hours before bed.
10 minutes outside as the sun gets lower.
Protein and vegetables; done 2 to 3 hours before bed.
Warm, low lights; screens away; warm shower.
Reading, light stretching or slow breathing; lights low, no screens.
Cool room 18 to 20 °C; same time, give or take 30 minutes.
Bright by day, low and warm by night.
Warm shower, cool bedroom, warmer morning.
Same bed and wake time, give or take 30 minutes.
Supplements come last, not first. No product replaces these habits; at best it supports a night that is already set up well. A principle Huberman shares in Protocols, paraphrased.
What the night needs, and which nutrients and plant compounds researchers have looked at for each part of it.
| The physiology | What it needs | What has been studied |
|---|---|---|
| Core temperature must drop to fall asleep | Heat moved from core to skin | Glycine has been studied for its effect on peripheral blood flow and core temperature (Bannai 2012). |
| Cortisol low at night | A calmer stress response in the evening | Ashwagandha root extract and L-ornithine have been studied for stress markers, including cortisol (Salve 2019; Miyake 2014). |
| Melatonin in darkness | Tryptophan, 5-HTP, vitamin B6 | 5-HTP and B6 sit on the pathway: tryptophan to 5-HTP to serotonin to melatonin, made in darkness. Tart cherry contains natural polyphenols (Howatson 2012). |
| A quieter nervous system | Magnesium, calming signals | Magnesium contributes to normal functioning of the nervous system and normal psychological function (EU claim). L-theanine and chamomile are traditional wind-down ingredients (Hidese 2019; Chang 2016). |
| Overnight tissue repair | Amino acids, zinc | Glycine is a key collagen building block; zinc contributes to normal protein synthesis and to the maintenance of normal skin, hair and nails (EU claim). |
| Muscle recovery | Antioxidant support | Powdered Montmorency tart cherry has been studied in runners for recovery after exercise (Levers 2015). |
| Gut repair and rhythm | Beneficial bacteria, nutrients | Bacillus coagulans MTCC 5856, a spore-forming strain, has been studied for digestive comfort (Majeed 2016). |
| Hormonal balance | B vitamins, inositol | Vitamin B6 contributes to the regulation of hormonal activity (EU claim). Myo-inositol is widely researched in women’s hormonal health (Unfer 2017). |
Tart cherry naturally contains small amounts of melatonin and polyphenols; in a lab model its compounds slowed IDO, an enzyme that diverts tryptophan away from this pathway (Losso 2018). EU-authorised health claims are marked; other statements describe published research on individual nutrients and plant compounds, not the effect of any product.
Each line gives the dose and form used in the study. The findings describe those study conditions only.
| Nutrient or compound | Study | Dose studied | Reported finding |
|---|---|---|---|
| Ashwagandha root extract | Salve et al., Cureus 2019; 58 healthy, stressed adults, 8 weeks | 250 or 600 mg a day | Lower serum cortisol and better self-rated sleep quality vs placebo; stronger effects at 600 mg. |
| Glycine | Yamadera et al., Sleep Biol Rhythms 2007 | 3 g before bed | Better subjective sleep quality; faster entry into deep sleep on polysomnography. |
| L-Ornithine | Miyake et al., Nutr J 2014; healthy workers, 8 weeks | 400 mg a day | Lower serum cortisol and cortisol/DHEA-S ratio; better perceived sleep quality. |
| Montmorency tart cherry juice | Howatson et al., Eur J Nutr 2012; 20 adults, 7 days | Juice concentrate | Higher urinary melatonin; longer total sleep time and sleep efficiency. |
| Montmorency tart cherry powder | Levers et al., JISSN 2015; runners | 480 mg a day | Less muscle soreness and markers of muscle damage after a half-marathon. |
| L-Theanine | Hidese et al., Nutrients 2019; 30 adults, 4 weeks | 200 mg a day | Improvements in stress-related symptoms and sleep-quality scores. |
| Chamomile | Chang and Chen, J Adv Nurs 2016; 80 postnatal women, 2 weeks | Chamomile tea | Better sleep-quality scores and mood vs control while drinking the tea. |
| Bacillus coagulans MTCC 5856 | Majeed et al., Nutr J 2016; adults with IBS, 90 days | 2 bn spores a day | Reduced bloating, discomfort and other digestive symptoms vs placebo. |
| Reishi (Ganoderma lucidum) | Cui et al., J Ethnopharmacol 2012 | Animal study | Increased sleep time in rodents. Human data are still limited. |
Study outcomes do not guarantee individual results. Food supplements are not intended to diagnose, treat or prevent any disease.
Magnesium contributes to normal psychological function, normal functioning of the nervous system and the reduction of tiredness and fatigue. Zinc contributes to normal cognitive function, the maintenance of normal skin, hair and nails, and the protection of cells from oxidative stress. Vitamin B6 contributes to the regulation of hormonal activity and normal psychological function. Vitamin B12 and folate contribute to the reduction of tiredness and fatigue.
If sleep problems persist after a few weeks of these habits, speak to your doctor or a sleep specialist. Snoring with pauses in breathing, restless legs or long-lasting insomnia deserve proper assessment. Cognitive behavioural therapy for insomnia (CBT-I) is a well-supported first-line approach. If you take medication or are pregnant or breastfeeding, check with your doctor before adding a supplement.
Areta JL, et al. Timing and distribution of protein ingestion during prolonged recovery from resistance exercise alters myofibrillar protein synthesis. J Physiol. 2013;591(9):2319–2331.
Axelsson J, et al. Beauty sleep: experimental study on the perceived health and attractiveness of sleep deprived people. BMJ. 2010;341:c6614.
Bannai M, Kawai N. New therapeutic strategy for amino acid medicine: glycine improves the quality of sleep. J Pharmacol Sci. 2012;118(2):145–148.
Bubenik GA. Gastrointestinal melatonin: localization, function, and clinical relevance. Dig Dis Sci. 2002;47(10):2336–2348.
Burke LE, Wang J, Sevick MA. Self-monitoring in weight loss: a systematic review of the literature. J Am Diet Assoc. 2011;111(1):92–102.
Byrne NM, et al. Intermittent energy restriction improves weight loss efficiency in obese men: the MATADOR study. Int J Obes. 2018;42(2):129–138.
Cava E, Yeat NC, Mittendorfer B. Preserving healthy muscle during weight loss. Adv Nutr. 2017;8(3):511–519.
Chang AM, et al. Evening use of light-emitting eReaders negatively affects sleep, circadian timing, and next-morning alertness. PNAS. 2015;112(4):1232–1237.
Chang SM, Chen CH. Effects of an intervention with drinking chamomile tea on sleep quality and depression in sleep disturbed postnatal women. J Adv Nurs. 2016;72(2):306–315.
Conlin LA, et al. Flexible vs. rigid dieting in resistance-trained individuals seeking to optimize their physiques: a randomized controlled trial. J Int Soc Sports Nutr. 2021;18(1):52.
Cui XY, et al. Extract of Ganoderma lucidum prolongs sleep time in rats. J Ethnopharmacol. 2012;139(3):796–800.
Fasano A. Leaky gut and autoimmune diseases. Clin Rev Allergy Immunol. 2012;42(1):71–78.
Gardner CD, et al. Effect of low-fat vs low-carbohydrate diet on 12-month weight loss in overweight adults: the DIETFITS randomized clinical trial. JAMA. 2018;319(7):667–679.
Hall KD, et al. Quantification of the effect of energy imbalance on bodyweight. Lancet. 2011;378(9793):826–837.
Hall KD, et al. Calorie for calorie, dietary fat restriction results in more body fat loss than carbohydrate restriction in people with obesity. Cell Metab. 2015;22(3):427–436.
Hidese S, et al. Effects of L-theanine administration on stress-related symptoms and cognitive functions in healthy adults. Nutrients. 2019;11(10):2362.
Howatson G, et al. Effect of tart cherry juice (Prunus cerasus) on melatonin levels and enhanced sleep quality. Eur J Nutr. 2012;51(8):909–916.
Huberman AD. Protocols: An Operating Manual for the Human Body. 2025.
Jakubowicz D, et al. High caloric intake at breakfast vs. dinner differentially influences weight loss of overweight and obese women. Obesity. 2013;21(12):2504–2512.
Kerksick CM, et al. International Society of Sports Nutrition position stand: nutrient timing. J Int Soc Sports Nutr. 2017;14:33.
Leproult R, et al. Sleep loss results in an elevation of cortisol levels the next evening. Sleep. 1997;20(10):865–870.
Levers K, et al. Effects of powdered Montmorency tart cherry supplementation on acute endurance exercise performance. J Int Soc Sports Nutr. 2015;12:41.
Losso JN, et al. Pilot study of the tart cherry juice for the treatment of insomnia and investigation of mechanisms. Am J Ther. 2018;25(2):e194–e201.
Majeed M, et al. Bacillus coagulans MTCC 5856 supplementation in the management of diarrhea predominant irritable bowel syndrome. Nutr J. 2016;15:21.
McDonald D, et al. American Gut: an open platform for citizen science microbiome research. mSystems. 2018;3(3):e00031-18.
Miyake M, et al. Randomised controlled trial of the effects of L-ornithine on stress markers and sleep quality in healthy workers. Nutr J. 2014;13:53.
Morton RW, et al. A systematic review, meta-analysis and meta-regression of the effect of protein supplementation on resistance training-induced gains in muscle mass and strength. Br J Sports Med. 2018;52(6):376–384.
Mountjoy M, et al. IOC consensus statement on relative energy deficiency in sport (RED-S): 2018 update. Br J Sports Med. 2018;52(11):687–697.
Oyetakin-White P, et al. Does poor sleep quality affect skin ageing? Clin Exp Dermatol. 2015;40(1):17–22.
Salve J, et al. Adaptogenic and anxiolytic effects of ashwagandha root extract in healthy adults. Cureus. 2019;11(12):e6466.
Schoenfeld BJ, Aragon AA. How much protein can the body use in a single meal for muscle-building? J Int Soc Sports Nutr. 2018;15:10.
St-Onge MP, et al. Fiber and saturated fat are associated with sleep arousals and slow wave sleep. J Clin Sleep Med. 2016;12(1):19–24.
Sundelin T, et al. Cues of fatigue: effects of sleep deprivation on facial appearance. Sleep. 2013;36(9):1355–1360.
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Yamadera W, et al. Glycine ingestion improves subjective sleep quality in human volunteers, correlating with polysomnographic changes. Sleep Biol Rhythms. 2007;5(2):126–131.
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This guide is for general education and is not medical advice. Food supplements are not a substitute for a varied, balanced diet and a healthy lifestyle. If you are pregnant, breastfeeding, under 18, managing a medical condition or taking medication, ask a healthcare professional before taking any supplement.
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