Stress is your body's way of responding to a threat, real or perceived. The body's defenses respond with what’s known as the “fight-or-flight” reaction or the "stress response."
Stress makes the heart beat faster, blood vessels constrict elevating blood pressure, blood sugar goes up, muscles tense, the digestive and reproductive systems shut down and the vagus nerve withdraws. These are all good things when it’s a short-term response to a genuine stressor. But mechanisms that are protective in the short-term become damaging over the long term. The long term constant activation of the stress response system erodes resilience and depletes metabolic reserve resilience. In other words, chronic stress is damages our bodies.
Stress is multi-factored and individual. An event that is incredibly stressful for one individual could be completely stress free for another. There’s a saying, “if you can’t measure it, you can’t improve it” but that doesn’t apply to stress. There’s no number that can be monitored. It’s not as simple as measuring the “stress hormone” cortisol because it’s more nuanced than that. Frankly, the best measure is if you feel stressed, then you’re stressed, but even that’s imperfect because one can lead a very harmonious life and be still be affected by stressors such as a high glycemic diet or toxic exposure.
Managing stress isn’t as simple as just taking a deep breath. But don’t stress out, with knowledge and certain practices, stress can be managed.
Causes of Stress
- Work pressure
- Financial worry
- Family issues
- Marital issues/divorce
- Loss of loved one
- Losing a job
- Raising children
- Perceived threat
- Caring for a loved one with difficult medical issue
- Chronic pain
- Chronic Illness diagnosis such as cancer, Multiple Sclerosis, Alzheimer’s etc.
- Over-exercise (produces high oxidative stress and prolonged elevated cortisol)
- Diet (glycemic control, food allergies/sensitivities) When insulin is chronically high, so is cortisol. If you are an adult and eat more than 30 grams of sugar a day, (one 12 ounce can of cola contains 39 grams of sugar) you are living in chronic stress (source: The Metabolic Approach to Cancer, Kindle location 4668 of 7162.). A poor diet can feed “bad bugs” in the gut (microbiome dysbiosis) thus deteriorating the gut–brain axis in regulating stress-related responses. Food sensitivities/allergies also place adrenal glands in chronic stress response.
- Prescription, over the counter, and recreational drugs
Toxic chemical exposure
- Heavy Metals
- Cleaning Products
- Body Care Products
- Airborne Chemicals
- Cigarette Smoke
The Damaging Effects of Stress
Chronic stress leads to dysfunction of the HPA Axis (Hypothalamic Pituitary Adrenal axis), also commonly referred to as adrenal fatigue. The hypothalmus in the brain produces CRF (corticotropin releasing factor), that stimulates the pituitary gland to release ACTH (andrenocoticotropic hormone), the ACTH causes the adrenal glands to release cortisol and other stress related hormones.
The more stress the body experiences, the more the adrenals have to work to produce cortisol, the harder the adrenals have to work, the more fatigued they become producing the less cortisol, less cortisol results in even more stress and inflammation.
Stress effects every single cell in the body. Every cell in our body has the ability to produce and receive neuropeptides which neurons use to communicate with each other. Stress changes the neuropeptides our cells release. When the neuropeptides serotonin, dopamine, and relaxin are exchanged they have a healthy effect on the immune system, but when certain neuropeptides such as cortisol, epinephrine, and adrenaline are produced over an extended period of time, they damage cells and weaken the immune system.
Stress and ApoE4
At the 2016 Ancestral Health Symposium, Dr Dale Bredesen, noted neurodegeneration researcher, presented a talk ApoE4 Mechanistics
In the presentation, Dr Bredesen explained that ApoE4 has been around for seven million years, it has served man literally since the dawn of mankind. He discussed how when our ancestors transitioned from tree dwellers to walking on the savannah new environmental insults were introduced: cuts to the feet, infections, fighting with others for food, going longer periods of time without food, fighting with predators, not cooking food, etc. An adaptive measure to increase survival in this new environment was inflammation. The ApoE4 pro-inflammatory state helped early man survive, it was a good thing. The ApoE3 allele showed up around 220,000 years ago, very “recently.” This was about the same time that man started using fire and cooking. ApoE3 is now the predominant genotype. The ApoE2 allele is a relative “newbie” showing up only around 80,000 years ago.
Dr Bredesen explained that one of the differences between ApoE4 and ApoE3 is that ApoE4 is RelA dominant. A RelA dominant state says, “I’m under attack, I want to set up most of my resources for inflammation, my NF-kappaB (NFκB) is going to be activated, I’m not worried about longevity, I’m not worried about recycling, and I’m not worried about oxidative phosphorylation, because I need rapid response to microbes.” This state was good for early man.
ApoE3 is SirT1 dominant. A SirT1 dominant state wants to put resources into recycling, into longevity, into oxidative phosphorylation, it’s anti-inflammatory. RelA and SirT1 are mutually antagonistic, you can’t have both, but you’re not locked in either, with certain strategies, an ApoE4 carrier can push over into a SirT1 dominant state, but stress is not a friend to an ApoE4 carrier trying to attain a SirT1 state. ApoE4s are particularly susceptible to Alzheimer’s disease, cardiovascular disease, and shortened longevity. Stress is not the sole driver in each of these conditions, but it does play an important role.
Stress and the Brain
As discussed above the stress chain of events in the HPA axis ends with pumping out high levels of cortisol. High levels of cortisol damages neurons, especially in the hippocampus contributing to cognitive, and in particular, memory decline.
Dr Bredesen emphasized reducing stress as one of the four pillars of his protocol: Diet, Exercise, Sleep, and Stress see Reduce stress
The early belief was that stress increases the cells that are dying in the brain, but according to Dr Daniela Kaufer from the Helen Wills Neuroscience Institute and the University of California, Berkeley, The Effects of Chronic Stress on the Brain stress itself does not kill brain cells, but stress makes those cells more vulnerable. Stress makes us more susceptible to the damage of other conditions that deteriorate brain heath. For example, if a person has Alzheimer’s disease, those cells are weaker, more likely to die, and stress can push them over the edge.
When it comes to neurons, we generate them throughout our life, even those in their 80s and 90s generate new neurons. But as we get older we generate fewer and fewer. Chronic stress depresses neuron generation. Depressing neuronal generation when your production is low to begin with isn’t a formula for success.
Stress also increases a number of risk factors that contribute to cognitive decline and Alzheimer’ disease, including increasing blood glucose levels, body fat storage which leads to insulin resistance, carbohydrate craving, leaky gut with its resulting inflammation, permeability of the blood brain barrier, calcium release, and hyperstimulation of neurons. Stress also attacks factors that protect against Alzheimer’s disease.
According to this study, the largest of its kind with over 2,000 participants mostly in their 40s, Circulating cortisol and cognitive and structural brain measures, published October 24, 2018, those with the highest levels of the stress-related hormone cortisol performed worse on tests of memory, organization, visual perception and attention. Higher cortisol levels were also found to be associated with lower brain volume and other changes that are often seen as precursors to Alzheimer’s disease. The association was particularly evident in women. ApoE4 was cited by the study with “no effect modification by the APOE4 genotype of the relations of cortisol and cognition or imaging traits.”
Women with midlife stress are more likely to develop Alzheimer’s decades later. Stressful life events and cognitive decline: Sex differences in the Baltimore Epidemiologic Catchment Area Follow‐Up Study (C.A. Munro, et al, Mar 2019)
For a deeper dive into stress as a risk factor for Alzheimer's Disease, this review article is quite comprehensive and endeavors to critically analyze the current knowledge (as of 2019) supporting stress as a potential risk factor for Alzheimer's: Risk Factors for Alzheimer’s Disease: Focus on Stress (A. Caruso, et al, Sept 2019)
Stress and the Cardiovascular System
According to the American Institute of Stress , “the relationship between stress, heart disease and sudden death has been recognized since antiquity. The incidence of heart attacks and sudden death have been shown to increase significantly following the acute stress of natural disasters like hurricanes, earthquakes and tsunamis and as a consequence of any severe stressor that evokes “fight or flight’ responses. Coronary heart disease is also much more common in individuals subjected to chronic stress and recent research has focused on how to identify and prevent this growing problem, particularly with respect to job stress.”
Similarly, WebMD recognizes stress as bad for heart health, “If you're often stressed, and you don't have good ways to manage it, you are more likely to have heart disease, high blood pressure, chest pain, or irregular heartbeats.…Studies also link stress to changes in the way blood clots, which makes a heart attack more likely.”
Stress often also presents a downward spiral. Many responses to stress are unhealthy to the cardiovascular system: smoking, overeating, inadequate sleep, isolating from others, or not exercising. Those things only stress a person more and the response to stress is more smoking, overeating, inadequate sleep, etc. Thus the downward health spiral.
Stress and Longevity
Telomeres are part of a human cell that that indicate how our cells are aging. According to T.A Sciences "What is a Telomere? short telomeres are connected to premature cellular aging. “Telomeres are the caps at the end of each strand of DNA that protect our chromosomes, like the plastic tips at the end of shoelaces. Without the coating, shoelaces become frayed until they can no longer do their job, just as without telomeres, DNA strands become damaged and our cells can’t do their job”
Elizabeth Blackborn, a Nobel laureate who is currently the President of the Salk Institute for Biological Studies and previously a biological researcher at the University of California, San Francisco, has studied telomeres extensively. Among her research, she looked at the telomeres of caregivers who are constantly faced with stress and discovered the telomeres were shorter in study participants who self-reported more stress. For a deeper dive, see The Telomere Effect
Stress also impacts immune system negatively in two ways:
- By creating chronic inflammation that harms tissues
- By suppressing immune cells needed to fight infection
Research has shown that those exposed to chronic social conflict experience high levels of stress and subsequent dysregulation of the immune system. This increases their vulnerability to infectious and autoimmune disease. Chronic stress can reduce our immune system’s ability to fight off antigens, the harmful invaders that can make us ill. This can make us more vulnerable to infections and disease.
This report Psychological Stress and the Human Immune System: A Meta-Analytic Study of 30 Years of Inquiry meta-analyzes more than 300 empirical articles describing a relationship between psychological stress and parameters of the immune system in human participants. From Conclusion:
- “The results of this meta-analysis support this assertion in one sense: Stressors with the temporal parameters of the fight-or-flight situations faced by humans’ evolutionary ancestors elicited potentially beneficial changes in the immune system. The more a stressor deviated from those parameters by becoming more chronic, however, the more components of the immune system were affected in a potentially detrimental way.”
Strategies to deal with Stress
Eating seasonal, organic, real (not processed or packaged – containing preservatives, additives, artificial flavors, artificial colors, etc.), low-glycemic foods can be considered a stress-reducing activity. It’s also very important to avoid food sensitivities/allergies. Our genetic material is older than we are. After thriving for millions of years, our DNA has specific expectations for certain foods, (i.e. not recently introduced from an evolutionary standpoint, such as foods native to North America or foods that are genetically modified, see Dr Gundry's Protocol). When fed "unfamiliar foods" our genes don’t react well, they get imbalanced, resulting in health concerns. A diet filled with foods of little nutrient value is also a huge stress on the body.
Low Glycemic Diet
Perhaps the most important strategy to lower stress with diet is to follow a low glycemic diet. The glycemic effect refers to how much food impacts blood glucose (sugar), see Insulin Resistance. According to The University of California at San Francisco Sugar Science website the World Health Organization recommends a daily allowance of 25 grams of sugar if on a 2,000 calorie a day diet, yet the average American consumes 19.5 teaspoons (82 grams) every day. When consumed, sugar and carbohydrates produce high levels of glucose (blood sugar). Insulin is subsequently released by the pancreas in response to high blood sugar in the bloodstream. The primary function of cortisol is to balance the effect of insulin, so if insulin is chronically high, so is cortisol. That evening dessert not only spikes insulin but cortisol too. As discussed in Circadian Rhythm below, cortisol levels should be trending down in the evening, that late day insulin/cortisol spike makes it harder to fall asleep, further stressing the body.
Food Allergies and Sensitivities
Second to the stress caused by our high sugar diets is our overconsumption of foods to which we’re sensitive or allergic these place adrenal glands in chronic stress response. When a food allergen is consumed the body produces histamine, an inflammation-producing compound modulated by cortisol. The more histamine that is released, the more cortisol it takes to control the inflammatory response, the harder the adrenals have to work to produce more cortisol. The harder the the adrenals have to work, the more fatigued they become, and less cortisol they produce, allowing histamine to inflame tissues even more.
Salt has been demonized in recent times but salt (sodium) is an essential nutrient for human health. As already discussed, cortisol is produced by the adrenal cortex, but so are other corticosteroids. Aldosterone is one of those corticosteroids, it balances fluid and salt. Aldosterone encourages kidneys to keep more salt (sodium), but when stressed, producing aldosterone is more difficult. According to this article, Did you know salt reduces stress? “Scientific research has shown, both in animals and in humans, that increased levels of salt consumption are very effective in reducing levels of cortisol.”
With an emphasis on dark. Just because the label on the chocolate says “dark” it may not be enough, look for those at least 70%. This means we’re not talking a typical candy bar made of milk chocolate here. The operative ingredient is cacao, which is bitter not sweet, but is also filled with polyphenols and can boost mood and brings a sense of calm as well as other health benefits. For more info: Dark Chocolate Reduces Stress and Inflammation, Boosts Memory and Mood and Dark chocolate consumption reduces stress and inflammation
Tea probably won’t eliminate all stress, but some teas are calming, plus drinking tea is also a slow, calm activity and if drinking tea becomes part of a routine, routines themselves are naturally relaxing.
- Peppermint Tea – Contains menthol a natural muscle relaxant. Don’t drink if pregnant.
- Chamomile Tea – Relaxing and is said to help with insomnia
- Lemon Balm Tea – Relaxes without drowsiness, also elevates mood
- Passion Flower Tea – Good for anxiety and helps with sleep
- Green Tea – Although caffeinated, has a polyphenol to combat anxiety and stress. Helps stay alert but calm.
- Rose Tea – Calming and helps you sleep well
Adaptogens are natural substances that work with a person’s body and help them adapt, most notably, to stress. They possess stress-protective effects including antifatigue and anti-infection, and are also restorative while normalizing impact on the HPA axis.
There are several adaptogen herbs, but most notable: ginseng, rhodiola, holy basil, ashwaganda, and licorice root.
For more info:
- Adaptogenic Herbs: List, Effectiveness, and Health Benefits
- 7 Adaptogenic Herbs or Adaptogens that Help Reduce Stress
- How Adaptogenic Herbs Reduce Stress
After food, emotions and thought patterns are our primary epigenetic modifiers.
Dr Candace Pert, a molecular biologist and author of Molecules of Emotion discovered that certain proteins and immune system cytokines facilitate and integrate communication between the brain and body. In other words our bodies reflect our thoughts.
Certain thought patterns can result in greater stress and negative health responses:
- Being overly conscientious and responsible
- Carrying others’ burdens
- Poorly defined personal boundaries
- Wanting to please other people
- Needing approval
- Internalizing toxic emotions, such as anger, resentment, and hostility, and difficulty expressing them
- Having a low threshold for stress
For those who identify with such patterns and traits, an essential read is Dr Brené Brown’s NY Times best selling book Daring Greatly. Dr Brown also has a TED talk The power of Vulnerability which as of the time of writing this Wiki article, (Aug 2018) has been viewed over 35 million times.
In another TED talk, How to Make Stress Your Friend health psychologist Kelly McGonigal suggests changing your attitude about stress. In her talk, she discusses a study where she said, “People who experienced a lot of stress but did not view stress as harmful were no more likely to die. In fact, they had the lowest risk of dying of anyone in the study, including people who had relatively little stress.” She also related a study where participants who learned to view the stress response as helpful for their performance, “well, they were less stressed out, less anxious, more confident, but the most fascinating finding to me was how their physical stress response changed."
Take a Stress Management Course
There are classes, local and on-line, that can help a participant focus on the life skill of stress management. One of the more popular courses is MBSR - Mindfulness Based Stress Reduction offered by various facilities including hospitals, retreat centers, yoga facilities, and more. For more info, visit MBSR: 25 Mindfulness-Based Stress Reduction Exercises and Courses.
MBSR was originally developed in the 1970s to treat hospital patients struggling with life’s difficulties and physical and/or mental illness. Due to its wide applicability, MBSR has since been used by a broad range of people. MBSR has its roots in spiritual teachings, but the program itself is secular. MBSR classes focus on teaching:
- mind and body awareness to reduce the physiological effects of stress, pain or illness
- non-judgemental awareness in daily life
- promoting serenity and clarity in each moment
- experiencing a more joyful life
- accessing inner resources for healing and stress management
- progressive muscle relaxation
- mindfulness meditation
The body follows certain rhythms or cycles. Circadian rhythm is a 24-hour internal clock found in most living things: animals, plants, even tiny microbes. Circadian oscillations even occur in the cells of our organs such as the liver and heart. Circadian rhythms influence sleep-wake cycles, hormone release, eating habits and digestion, body temperature, and other important bodily functions. The main cueing influence is daylight. Light turns on or off genes that control the molecular structure of biological clocks.. Changing the light-dark cycles can speed up or slow down these circadian rhythms.
The vast majority of hormones follow a daily cycle, but the most important hormones affected by the circadian clock are cortisol and melatonin.
- Highest in morning, helps wake us up. Lowest at night, disruption in this cycle results in body dysfunction and sleepless nights.
- Referred to as the stress hormone, too much is damaging
- Produced in the pineal gland in the brain chemically causes drowsiness and lowers body temperature
- Melatonin is produced in darkness, usually at night, production is suppressed by light, particularly blue light emitted by electronics and energy-efficient lightbulbs (LEDs, CFLs)
- When melatonin is secreted, cortisol will not be.
- Melatonin is a hormone the body’s first line of defense against oxidative stress. It is a direct scavenger of oxygen radicals and reactive nitrogen species.
Oxidative stress isn’t the same as job stress, you can sense job stress, you can’t sense oxidative stress but the body certainly does, it damages mitochondria and causes inflammation. Oxidative stress is the reason cigarette smoking is bad. Oxidative stress is essentially an imbalance between the production of free radicals and the ability of the body to counteract their harmful effects with antioxidants. Oxidative stress is of particular interest to ApoE4s. Per Oxidative Stress and Neurodegenerative Diseases: A Review of Upstream and Downstream Antioxidant Therapeutic Options
- “Oxidative damage can lead to a number of degenerative diseases in humans such as cancer, diabetes, cardiovascular disease, and “ROS [Reactive Oxygen Species aka free radicals] are particularly active in the brain and neuronal tissue as the excitatory amino acids and neurotransmitters, whose metabolism is factory of ROS, which are unique to the brain and serve as sources of oxidative stress.” (bold font added for emphasis.)
Circadian Rhythm Strategies to Employ
- Perhaps the best way to recalibrate your circadian rhythm is by going camping. Living to the cycles of the sun and darkness for a few days will reset your internal clock. Experience nature through all five senses – see the beauty of nature around you, listen to the birds, inhale the fragrance of the trees, dabble your fingers or toes in a stream, taste the fresh air and you’ll get the additional stress relieving benefit of Nature Therapy, also sometimes referred to as Forest Bathing. For more info:
- The benefits of nature experience: Improved affect and cognition
- Effects of Forest Bathing on Cardiovascular and Metabolic Parameters in Middle-Aged Males.
- Would You Be Happier Living in a Greener Urban Area? A Fixed-Effects Analysis of Panel Data
- Exposure to neighborhood green space and mental health: evidence from the survey of the health of Wisconsin
- Neural basis for the relationship between frequency of going outdoors and depressive mood in older adults
Other Circadian Rhythm strategies:
- Sleep in a darkened room or use an eye mask – Even dim light can interfere with a person's circadian rhythm and melatonin secretion. Hang blackout curtains, cover up any LED lights on phones, toothbrushes, baby monitors, or whatever other gadgets you have in in your room. Ditch nightlights or switch to ones with red light bulbs.
- Expose yourself to bright light during the day. Expose your naked eyes, (i.e. no sunglasses, prescription glasses or car windows) to sunlight first thing in the morning for 15 minutes (30 if cloudy) this will start the hormone cascade.
- Wear blue-blocking glasses under artificial lights or working on a computer/electronic device, especially after the sun goes down.
- Install an app that filters the blue/green wavelength on your computer/phone at night.
Exercise can reduce stress, as long as it's not too much. Over exercise produces high oxidative stress and prolonged elevated cortisol. Also see Exercise - Types, Lengths, and Benefits. Instead of going to the gym with the artificial lights, blaring music, and noisy weight machines, try going for a relaxing walk or jog outside. Listen to the birds singing and feel the breeze in the air or use earbuds/headphones to listen to inspiring music and focus on the pleasure and sensation of your movement.
To meditate: sit or lie down comfortably, close your eyes, breathe naturally, and focus your attention on your breath, clearing your mind and if your mind wanders, refocus on the breath. Sounds simple, yet many find this difficult. There are plenty of books, websites, DVDs, classes, even apps to teach meditation and offer guided meditation. Meditation is effective at calming, but should be practiced regularly for full effect.
Some websites for more info:
- Wikihow - Meditate
- How to Meditate
- Meditation 101: Techniques, Benefits, and a Beginner's How-To
- Kirtan Kriya (Sa Ta Na Ma Meditation) Kirtan Kriya meditation has been studied and appears to improve brain health when practiced just 12 minutes a day.
Recommended in Dr Bredesen’s book, The End of Alzheimer’s, Neural Agility is one of the recorded tracks of the product “RevitaMind” sold by Active Minds Global. Neural Agility is an audio track that sounds like a pulsing beat with white noise, so it is “effortless” meditation which not only relaxes you but is said to stimulate cognitive function too.
While sitting still and meditating can be very good for reducing stress, many find this difficult. But everyone breathes, so breathing exercises can be an effective alternative and some breathing exercises can be done inconspicuously in public.
- Inhale 1, 2, 3, 4
- Hold 1, 2, 3, 4
- Exhale 1, 2, 3, 4
- Hold 1, 2, 3, 4
Focus on the breath and repeat the same process over until you reach a calm state. You can add simple meditative thoughts to this, see Simple Stress Relief w/Square Breathing
Left nostril breathing
According to Left Nostril Breathing (For calming)
- “When you need to calm down, when your mind is racing faster than a hurricane, or when you can’t go to sleep, try left nostril (Ida) breathing. Simply take your right hand and, with your fingers outstretched, block off your right nostril by putting gentle pressure on it with your right thumb. Be sure to keep the rest of your fingers straight and pointing up towards the sky; the fingers act like antennas for the “cosmic” energy that surrounds us all. (Alternately, if sticking your fingers up in front of all your friends might not be the most appropriate thing to do, use any finger to block off the side of the nose)
- With a long, slow, deep breath, gently inhale through your left nostril. Then, just as gently, exhale long, slowly and completely, again through the left nostril. Relax your body as you feel the relaxing, cooling breath bringing new life into your body. Relax even deeper with each exhale as you breathe out all tension, all stress, and all disease.”
Deep Breathing, Breath Focus, Equal Breathing In and Out, Progressive Muscle Relaxation and Modified Lion’s Breath
See WebMD's Breathing Techniques for Stress Relief for more information on these breathing techniques.
Guided Breathing Meditation MP3 for download
In this link, Guided-Breathing-Exercise-with-Patrick-McKeown breathing instructor Patrick McKeown offers a 20 minute guided breathing meditation. The mp3 can be downloaded from the link.
Fractals in art and architecture
Fractals are patterns that look similar when repeated at different scales.
Incorporating these shapes on your screen saver or around your home may reduce stress.
The Potential of Biophilic Fractal Designs to Promote Health and Performance: A Review of Experiments and Applications(Taylor, R.P., Sustainability 2021)
- Fractal objects are prevalent in natural scenery. Their repetition of patterns at increasingly fine magnifications creates a rich complexity. .. These enhanced capabilities generate an aesthetic experience and physiological stress reduction.
The Stress-Reducing Effect of Fractal Architecture(Neda Ziabakhsh and Maryam Ghavami, 2016)
- This paper reviews the fundamental concept of nature’s fractal geometry in an architectural context, and presents the potential for incorporating the fractal patterns into art and architecture as a novel approach to reducing stress.
Hum or chant “OM” Hum into Health
Get a pet A pet gives purpose to life. According to 6 Ways Pets Can Improve Your Health “People with pets are generally happier, more trusting, and less lonely than those who don't have pets.”
From this study Cat ownership and the Risk of Fatal Cardiovascular Diseases. Results from the Second National Health and Nutrition Examination Study Mortality Follow-up Study., “The presence of pets has been associated with reduction of stress and blood pressure and therefore may reduce the risk of cardiovascular diseases.”
A dog will force you to get outside into fresh air and sunshine as they need to be walked daily. Walking a dog will also helps to connect with other people.
Having a “fur-baby” curl up next to you, look at you with those big eyes, purr (if a cat), and nap next to you while you gently pet it is very soothing.
Even an aquarium of fish can be a stress reliever, see Fish tanks lower blood pressure and heart rate.