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Physiological sigh: the fastest way to calm down, according to a Stanford study

In 2023, a Stanford University team (Balban, Spiegel, Huberman et al.) published a month-long randomized controlled trial with 114 participants in the journal Cell Reports Medicine. It compared four daily five-minute practices: cyclic sighing (two inhales through the nose and a long exhale), box breathing, inhale-focused breathing, and classic mindfulness meditation (passively observing the breath).

After a month, all four groups reported better mood and lower anxiety, but cyclic sighing had the largest effect on mood improvement of all the practices and lowered resting breathing rate the most — a measurable sign of the body calming down. The difference was already visible after a single five-minute session and kept growing with regular repetition over 28 days.

Zdroj: Balban a kol., Brief structured respiration practices enhance mood and reduce physiological arousal, Cell Reports Medicine, 2023.

Box breathing: the technique used by first responders and Navy SEALs, under scientific scrutiny

Box breathing (inhale, hold, exhale and hold, all equal in length) was made famous by Navy SEALs and first responders as a way to stay calm and focused in high-pressure situations. In the Stanford study mentioned above, box breathing was one of four techniques tested and also improved participants’ mood and reduced anxiety compared to baseline — but in direct comparison it lagged behind cyclic sighing, which had the strongest effect in that study.

That doesn’t mean box breathing doesn’t work — rather, its even rhythm is great for maintaining focus and calm during a demanding task, while the long exhale in cyclic sighing works more strongly in a moment of acute stress.

Zdroj: Balban a kol., Cell Reports Medicine, 2023.

Resonant breathing and heart rate variability (HRV)

Breathing at a pace of around 6 breaths per minute (the so-called resonant frequency) is the basis of a method called HRV biofeedback. A 2017 study published in Frontiers in Public Health (Steffen et al.) found that 15 minutes of breathing at this rate increased the HRV ratio linked to higher parasympathetic nervous system activity and improved participants’ mood compared to sitting quietly.

Review studies further show that breathing at around 0.1 Hz (roughly 6 breaths/min) oscillates the heart rate exactly in the frequency band linked to vagus nerve activity — one of the mechanisms by which slow breathing builds long-term stress resilience.

Source: Steffen et al., Frontiers in Public Health, 2017; review study in Frontiers in Psychology, 2021.

Why a longer exhale helps: the role of the vagus nerve

Several techniques (Calm, 4-7-8, cyclic sighing) rely on the exhale being longer than the inhale. Reviews from recent years (e.g. Gerritsen & Band, 2018, Frontiers in Human Neuroscience) describe the mechanism by which slow breathing with a prolonged exhale stimulates the vagus nerve and activates the parasympathetic branch of the nervous system — the one that slows the body down and puts it into rest mode, as opposed to the sympathetic branch responsible for the „fight or flight“ response.

Systematic reviews of slow-breathing studies agree that the effect is real and measurable (lower heart rate, higher HRV), although the exact size of the effect varies with the specific technique, the length of the inhale/exhale, and how long the practice is kept up.

Zdroj: Gerritsen & Band, Frontiers in Human Neuroscience, 2018; Zaccaro a kol., Frontiers in Human Neuroscience, 2018.

4-7-8: what we know about Dr. Andrew Weil’s technique

The 4-7-8 technique (inhale 4 s, hold 7 s, exhale 8 s) was popularized by American physician Dr. Andrew Weil as a modern adaptation of yogic pranayama. Compared to the physiological sigh or resonant breathing, the body of evidence is younger and smaller — but promising results aren’t missing either: smaller studies and recent reviews have found improvements in anxiety, sleep quality, blood pressure and heart rate variability in people with sleep disorders, after bariatric surgery, or with chronic lung disease.

In fairness, a large controlled trial comparable to the Stanford study on cyclic sighing is still missing for 4-7-8, and part of the evidence rests on smaller or uncontrolled studies. So it’s a safe and popular technique with reasonable scientific backing, not a miracle formula.

Source: scoping review of 4-7-8 breathing, 2025; smaller clinical studies in COPD and sleep disorders.

Diaphragmatic breathing: why slow belly breathing calms attention and cortisol

Diaphragmatic (belly) breathing engages the diaphragm instead of shallow chest breathing, deepens the inhale and exhale, and naturally slows the breathing rate. A 2017 Chinese study published in Frontiers in Psychology (Ma et al.) divided 40 healthy adults into a group with eight weeks of diaphragmatic breathing training and a control group.

The trained group had significantly lower salivary cortisol, better sustained attention and lower negative emotion levels after the program compared to baseline — the control group showed none of these changes. The effect wasn’t just a subjective sense of calm, but a measurable change in a stress hormone.

Zdroj: Ma a kol., The Effect of Diaphragmatic Breathing on Attention, Negative Affect and Stress in Healthy Adults, Frontiers in Psychology, 2017.

Alternate-nostril breathing: what the research on Nadi Shodhana says

Alternate-nostril breathing (Nadi Shodhana, also anuloma-viloma) is one of the most studied yogic breathing techniques. A 2017 systematic review covering 44 randomized studies found strong evidence for a positive effect on the autonomic nervous system, cardiovascular parameters and cognitive function.

A specific study by Shirley Telles’s team found that 18 minutes of alternate-nostril breathing in healthy volunteers lowered blood pressure while also improving performance on an attention test requiring fine motor skills and focus. The mechanism is similar to other slow techniques — engaging the vagus nerve and shifting toward the parasympathetic, “rest” branch of the nervous system.

Source: Telles et al., Alternate-Nostril Yoga Breathing Reduced Blood Pressure While Increasing Performance in a Vigilance Test, Medical Science Monitor Basic Research, 2017; systematic review of 44 RCTs, International Journal of Research in Medical Sciences, 2017.

Lion’s breath: a release valve for tension, though with thinner scientific backing

Lion’s breath (simhasana pranayama) is a deep inhale through the nose followed by a forceful exhale through the mouth with the tongue stuck out, often with a quiet “ha.” Unlike slow techniques such as Coherent or Calm, it’s not primarily about slowing the breath, but about releasing tension in the face, jaw and neck through a pronounced movement of the facial muscles and a loud exhale.

Direct clinical studies focused only on lion’s breath are still scarce — it’s more of a traditional yogic technique whose effect rests on the generally documented benefits of pranayama for the nervous system, and on the experience that actively stretching the facial muscles genuinely reduces felt tension. So it’s more of a quick, accessible way to “let off steam” than a technique with a large body of evidence like the physiological sigh or box breathing.

Source: reviews on the effects of pranayama on the nervous system and anxiety; Cleveland Clinic and expert yoga sources on the mechanism of lion’s breath, 2022–2025.

Breathing and music: why pairing it with ambient works even better

Guided breathing works on its own, but slow, unobtrusive music can boost the effect further. Ambient and chillout with no strong beat doesn’t force the body to “match” the tempo of the track the way faster music does, so it doesn’t override the pace set by the pulsing orb — instead it creates a sonic backdrop that helps you stay focused on your breath and blocks out distracting sounds around you.

If you want to pair the breathing exercise with ambient music, try playing SYNTHLUCIDA RELAX PLAYER in the background and start the breathing exercise here on Uklidni To — keep the music playing in one tab and let the orb guide your breath in the other.

Magnesium: popular, but not miraculous

Magnesium has recently become one of the most popular supplements for calm and better sleep, largely thanks to social media. Reviews from recent years show that in people prone to anxiety or with lower magnesium levels, supplementing may slightly improve feelings of anxiety and sleep quality.

The evidence isn’t particularly strong yet — studies tend to be small and use different forms and doses of magnesium, so there’s no clear-cut recommendation. Still, it’s a cheap and safe supplement with minimal side effects, so it’s a reasonable one to try, especially in the evening before bed. Talk to a doctor or pharmacist before starting — magnesium can be problematic for people with kidney problems.

Source: systematic reviews of studies on magnesium and anxiety/sleep, 2017 and 2024.

L-theanine: calm without drowsiness, from green tea

L-theanine is an amino acid naturally found in green tea that, according to EEG studies, increases so-called alpha brain waves — linked to a relaxed but alert state, similar to light meditation. In small studies, a dose of around 200 mg before a stressful situation slightly reduced feelings of anxiety and the body’s stress response, without causing drowsiness.

Unlike classic calming medications, L-theanine doesn’t slow reaction time or affect memory. Combined with caffeine (for example in a cup of tea), research shows it helps ease the jitters caffeine can cause on its own — which is why tea is said to feel “smoother” than coffee.

Source: clinical studies on the effects of L-theanine on anxiety and brain alpha activity, 2004–2026.

Cold showers: why the shock comes first, and calm only afterward

Cold water on the skin first triggers a so-called cold shock — the body briefly speeds up breathing and heart rate and releases stress hormones, just like with any other stressor. Only after this initial shock does the vagus nerve activate and calm set in: the heart rate drops below baseline and the nervous system shifts into a calmer mode. The effect is therefore the opposite of what you might expect — calm arrives as a reaction to the cold subsiding, not during it.

A 2022 study confirmed that applying cold to the face after a stressful task helped calm heart rate and subjective stress faster than without the cold. Regular cold exposure over several weeks has also been linked in smaller studies to slightly better heart rate variability (HRV) and better mood. To start, a few seconds of cold water at the end of a shower is enough, gradually extending the time — and right after the shower it’s good to breathe slowly for a bit to reinforce the calming effect. People with heart problems, high blood pressure or who are pregnant should only try cold exposure after consulting a doctor, since a sharp cold shock can briefly raise heart rate and blood pressure.

Source: study on the effect of a cold facial stimulus (Cold Face Test) on acute stress, Scientific Reports, 2022; reviews of studies on the safety and effects of cold water on mental health, 2023–2026.

Caffeine and anxiety: when it helps and when it hurts

The relationship between caffeine and anxiety isn’t clear-cut. At lower doses and in people used to regular consumption, caffeine often improves focus and mood; at higher doses or in more sensitive individuals, it raises cortisol and can trigger or worsen feelings of nervousness and a racing heart — so the effect is quite individual and dose-dependent.

If you’re prone to anxiety or sleep poorly, it can help to limit caffeine to the morning and watch how your body reacts — for some people, just one extra cup is enough to trigger restlessness. It’s best to try a breathing exercise or a cold shower outside caffeine’s peak effect, when the body is naturally calmer.

Source: systematic review of the effect of caffeine on anxious behavior, 2023–2026; studies on caffeine and cortisol reactivity to stress.

Progressive muscle relaxation: tense and release

Progressive muscle relaxation (Edmund Jacobson’s method from the 1930s) works on a simple principle — you tense and then release individual muscle groups one by one, from the feet up to the face. This helps the body better notice the difference between tension and release, which in turn helps you recognize and let go of hidden muscle tension you wouldn’t normally notice.

Recent reviews in adults confirm that regular progressive muscle relaxation reduces anxiety, stress and symptoms of depression, including in older adults or people in hospital care. Sessions usually last 5 to 20 minutes and can be done anywhere, sitting or lying down — it pairs nicely with a breathing exercise, for example as an evening ritual before bed.

Source: systematic reviews of the effectiveness of progressive muscle relaxation on stress, anxiety and depression, 2024–2025.

Meditation: attention training that also changes the brain

Mindfulness meditation means consciously and non-judgmentally focusing your attention on the present moment — most often on the breath, bodily sensations, or sounds around you. Whenever the mind wanders to thoughts of the past or future, you simply notice it and gently bring your attention back, without self-criticism. The best-known and most-studied program is the eight-week MBSR (Mindfulness-Based Stress Reduction) course, created by Jon Kabat-Zinn in the 1970s.

A large 2014 meta-analysis of dozens of clinical studies found that meditation programs lead to a mild but consistent improvement in anxiety, depression and pain perception — an effect comparable to other active therapies, though not dramatic. Another study showed that after eight weeks of regular MBSR practice, participants had measurable changes in gray matter density in brain regions linked to learning, memory and emotional processing. The effect mainly comes with regular, longer-term practice; as a complement to breathing exercises, starting with 10-15 minutes a day is plenty.

Source: Goyal et al., Meditation Programs for Psychological Stress and Well-being: A Systematic Review and Meta-analysis, JAMA Internal Medicine, 2014; Hölzel et al., Mindfulness practice leads to increases in regional brain gray matter density, Psychiatry Research: Neuroimaging, 2011.

Time in nature: why a walk in the woods calms more than a walk through the city

According to attention restoration theory, urban environments constantly flood the brain with stimuli you must actively react to — traffic lights, traffic, crowds — which drains what’s called directed attention. Natural environments, by contrast, capture attention gently and effortlessly (rustling leaves, running water), letting the brain rest and “recharge.” On top of that, stress hormone levels and blood pressure tend to drop measurably faster in green spaces than in built-up environments.

A 2015 brain-imaging study found that a 90-minute walk in nature, compared to an equally long walk down a busy street, reduced activity in a brain region linked to dwelling on negative thoughts (rumination). More recent research has shown that even 20-30 minutes in green space — even just sitting in a park without moving — can measurably lower salivary cortisol during the day, with longer exposure bringing a bigger drop, though even a short “dose” of nature had an effect. It doesn’t have to be wilderness; a city park or a tree-lined street works too.

Zdroj: Bratman a kol., Nature experience reduces rumination and subgenual prefrontal cortex activation, PNAS, 2015; Hunter, Gillespie & Chen, Urban Nature Experiences Reduce Stress in the Context of Daily Life Based on Salivary Biomarkers, Frontiers in Psychology, 2019.

Alcohol and sleep: why a nightcap doesn’t help you fall asleep, it wrecks your sleep

Alcohol initially depresses the nervous system, so it can seem like it helps you fall asleep faster — but that effect is deceptive. As alcohol is metabolized overnight, the body enters a kind of mild withdrawal state: sleep becomes fragmented, you wake up more often (even if you don’t remember it in the morning), and REM sleep — during which emotions are processed and memory is consolidated — is significantly suppressed. The result is sleep that looks longer on the outside but is far less restorative.

Alcohol also relaxes the throat muscles, worsening snoring and increasing the risk of sleep apnea, and it’s a diuretic, which leads to waking up at night to use the bathroom. Regularly drinking before bed is therefore linked long-term to worse sleep quality, more daytime fatigue and higher anxiety — exactly the opposite of what people are looking for when they reach for a drink “to relax.” For restful sleep, it’s best to avoid alcohol in the evening entirely, or at least give it enough time to be metabolized before you lie down.

Source: reviews of studies on alcohol’s effect on sleep architecture and REM sleep, 2018–2024; research on the link between alcohol, sleep apnea and sleep fragmentation.

Nicotine: a stimulant the body mistakes for calm

A cigarette or vape is often seen as a way to “calm down,” but nicotine is actually a stimulant — it speeds up the heart rate, raises blood pressure and stimulates the nervous system, similar to caffeine. The sense of relief smokers describe is mostly related to withdrawal symptoms subsiding between cigarettes, not to any real calming effect of nicotine itself. Studies also show smokers have, on average, higher anxiety and stress levels than non-smokers or former smokers, and that anxiety declines long-term after quitting.

Nicotine affects sleep much like caffeine — it shortens total sleep time, delays falling asleep and leads to more frequent nighttime waking, partly due to nighttime withdrawal in regular smokers. For calmer sleep and lower anxiety, the clearly most effective step is to cut back on nicotine or quit entirely; if that’s not possible right away, at least avoiding it for a few hours before bed helps.

Source: reviews of studies on the effect of nicotine on anxiety and sleep, 2019–2023; research on the relationship between smoking, quitting and anxiety levels.

Sleep hygiene: consistency, darkness and cool temperature, according to research

Good sleep rests mainly on consistency. The body’s internal clock (circadian rhythm) sets itself best when you go to bed and wake up around the same time, even on weekends — an irregular schedule and frequent “catch-up” sleep are linked in newer studies to worse sleep quality and higher cardiovascular risk, even when the total number of sleep hours is similar.

Two environmental conditions have genuinely solid support in the data, according to review studies. The first is a cooler bedroom — body temperature naturally drops as you fall asleep, and a room temperature of around 18-20°C makes that drop easier, while an overheated room demonstrably worsens sleep. The second is darkness: light (including blue light from screens) suppresses melatonin production via the retina, so it’s recommended to limit bright light and screens roughly 1-3 hours before bed and sleep in a dark room or with an eye mask. Conversely, morning exposure to daylight helps set the internal clock to the right time. Pairing this with a breathing exercise like 4-7-8 or the Calm technique (see above) can make for a good evening ritual that builds on these habits.

Source: Irish et al., The role of sleep hygiene in promoting public health: A review of empirical evidence, Sleep Medicine Reviews, 2015; Chaput et al., Device-measured weekend catch-up sleep, mortality, and cardiovascular disease incidence in adults, Sleep, 2024; Harding, Franks & Wisden, The Temperature Dependence of Sleep, Frontiers in Neuroscience, 2019; light-exposure recommendations per Brown et al., 2022.

Diet and adequate protein: how food affects calm and mood

Protein supplies the body with amino acids the brain uses to make mood-related neurotransmitters — among them tryptophan, a precursor of serotonin. A study using whey protein rich in alpha-lactalbumin (a protein high in tryptophan) in people prone to stress found that regular use over several weeks lowered cortisol and improved mood under stress compared to a control group. Research on protein source (animal vs. plant) and mood is still mixed, though — some studies link higher animal protein intake to lower depression risk, others find no difference, so it’s more one factor among many than a guaranteed recipe.

A more practically important mechanism is different: protein in a meal slows sugar absorption and helps keep blood sugar more stable. A sharp drop in blood sugar after a skipped meal or a sweet snack without protein can cause shakiness, a racing heart, irritability and a feeling of anxiety that’s hard to tell apart from the “ordinary” kind. A 2021 review summarizing research on diet and anxiety lists regular meals with enough protein among the simple recommendations — alongside enough fiber and limiting refined sugar and alcohol. A smaller 2016 study also found that in people with generalized anxiety disorder and hypoglycemia-like symptoms, adjusting the diet in this direction eased their anxiety symptoms.

So how much protein is “enough”? According to the European Food Safety Authority (EFSA) reference intake, a healthy adult needs roughly 0.8 g of protein per kilogram of body weight per day — for someone weighing 70 kg, that works out to about 55-60 g a day. Physically active people and older adults, who naturally lose muscle mass, are often given higher recommendations, roughly 1.2 to 2.0 g per kilogram, ideally after checking with a doctor or dietitian. For more stable blood sugar throughout the day, it’s also often recommended to spread protein evenly across main meals — roughly 20-30 g per meal — rather than loading most of the daily amount onto dinner.

It’s also worth paying attention to where protein (and food in general) comes from. Highly processed foods — packaged snacks, sweetened drinks, instant meals with a long list of additives — have repeatedly been linked in recent years to a higher risk of depression and anxiety. A large 2023 US study followed over 31,000 women for more than ten years and found that those who ate the most ultra-processed food had a significantly higher risk of developing depression than those who ate the least; the strongest link showed up for drinks and foods with artificial sweeteners. A similar link between ultra-processed diets and the development of anxiety and depression was described in a Chinese cohort study the same year, covering more than 180,000 people. The exact mechanism isn’t clear yet — a combination of rapid blood-sugar swings, a poorer nutrient profile, and effects on the gut microbiome may all play a role — but the practical takeaway is similar to that for added sugar alone: it’s better to build protein and the rest of your diet mainly around less processed foods (meat, fish, eggs, dairy, legumes, nuts) than around packaged snacks and sweetened drinks.

Zdroj: Markus a kol., The bovine protein α-lactalbumin increases the plasma ratio of tryptophan to the other large neutral amino acids and improves mood under stress, American Journal of Clinical Nutrition, 2000; Aucoin a kol., Diet and Anxiety: A Scoping Review, Nutrients, 2021; Aucoin a kol., Generalized Anxiety Disorder and Hypoglycemia Symptoms Improved with Diet Modification, Case Reports in Psychiatry, 2016; EFSA, Dietary Reference Values for protein, 2012; Wang a kol., Association of Ultraprocessed Food Consumption With Risk of Depression, JAMA Network Open, 2023; Sun a kol., Association of ultra-processed food consumption with incident depression and anxiety, Food & Function, 2023.

Sugar and dopamine: why sweets lift your mood fast — and drop it just as fast

Sugar, especially the fast-absorbing kind (white bread, sweets, sweetened drinks), triggers dopamine release in the brain’s mesolimbic reward pathway — specifically in a region called the nucleus accumbens, the same part of the brain activated by addictive substances like nicotine or cocaine. A striking example is a 2013 imaging study in which men were given two milkshakes that looked identical — equally sweet, equal calories, the same amount of protein and fat — except one was formulated so its sugar was absorbed quickly (high glycemic index) and the other slowly. The faster-absorbing shake triggered stronger nucleus accumbens activity; the difference wasn’t in sweetness, but in how sharply the food raised blood glucose.

The same study also showed the flip side: four hours after the fast-absorbing shake, blood sugar was lower and participants reported feeling hungrier than after the slower version — and that’s exactly when nucleus accumbens activity peaked, as if the brain were asking for another hit. This blood-sugar crash ties closely into what the previous article on protein describes: without protein or fiber to slow sugar absorption, the drop in blood sugar comes faster and sharper, bringing fatigue, irritability and cravings for more sweets along with it. Protein in a meal therefore doesn’t just prevent hypoglycemia-like symptoms — it also indirectly dampens this dopamine rollercoaster.

When it comes to long-term effects on the dopamine system, big conclusions call for caution. In animals it’s well documented that repeated access to large amounts of sugar produces addiction-like effects — tolerance (needing an ever-larger dose for the same reward), withdrawal symptoms after stopping, and a reduced number of so-called D2 dopamine receptors. In humans, the question of “sugar addiction” is still debated among experts, and direct evidence of the exact same mechanism is missing — though there are indirect clues: people with obesity or binge-eating patterns show lower D2 receptor availability in the striatum in research, similar to some substance addictions. High sugar intake is also repeatedly linked to higher rates of depression in observational studies, though the exact mechanism (inflammation, metabolic changes, or changes in the reward system itself) isn’t certain yet, and it’s not a proven direct causal link.

Zdroj: Lennerz a kol., Effects of dietary glycemic index on brain regions related to reward and craving in men, American Journal of Clinical Nutrition, 2013; Avena, Rada & Hoebel, Evidence for sugar addiction: Behavioral and neurochemical effects of intermittent, excessive sugar intake, Neuroscience & Biobehavioral Reviews, 2008; Qin a kol., Sugar Addiction: Neural Mechanisms and Health Implications, Brain and Behavior, 2025.

Exercise and movement: how physical activity calms the mind too

The relationship between exercise and anxiety is one of the best-studied topics in sports psychology. A classic 1991 meta-analysis, later updated in 2015, confirmed that even a single bout of aerobic exercise can briefly reduce so-called state anxiety — the anxiety felt in that specific moment — with an effect comparable to other commonly used calming techniques. A broader 2015 meta-meta-analysis, summarizing eight earlier reviews covering more than 10,000 participants, then showed that regular physical activity reduces anxiety even in the general, non-clinical population — the effect is smaller, but statistically reliable.

Not all types of movement work exactly the same way, though. A more recent 2024 network meta-analysis focused on young people compared different types of exercise, and so-called mind-body exercise — movement paired with conscious breathing and focus, like yoga or tai chi — came out as the most effective for anxiety, followed closely by classic aerobic exercise like running or cycling. For a lasting effect, consistency also matters — a meta-analysis in older adults found that exercise programs shorter than 10 weeks didn’t significantly reduce anxiety, while longer programs did, and it didn’t matter much whether it was walking, aerobics or strength training. Combining both approaches makes sense: exercise briefly activates the body and releases stress hormones, and a breathing exercise afterward helps consciously bring that activated state back down to calm.

Source: Petruzzello et al., A Meta-Analysis on the Anxiety-Reducing Effects of Acute and Chronic Exercise, Sports Medicine, 1991, updated by Ensari et al., Meta-Analysis of Acute Exercise Effects on State Anxiety, Depression and Anxiety, 2015; Rebar et al., A Meta-Meta-Analysis of the Effect of Physical Activity on Depression and Anxiety in Non-Clinical Adult Populations, Health Psychology Review, 2015; Tian et al., Comparative Efficacy of Acute Exercise Intervention on Anxiety in Adolescents and Young Adults: A Network Meta-Analysis, Scandinavian Journal of Medicine & Science in Sports, 2024; Goodarzi et al., Effect of Physical Activity for Reducing Anxiety Symptoms in Older Adults, BMC Sports Science, Medicine and Rehabilitation, 2024.