Source: The Digital Artist/Pixabay

The stress hormone, cortisol, is public health enemy Number One. Scientists have known for years that elevated cortisol levels interfere with learning and , lower immune function and bone density, increase weight gain, blood pressure, cholesterol, and heart disease—the list goes on.

Chronic stress and elevated cortisol levels also increase one's risk for , mental illness, and lower life expectancy. This week, two separate studies were published in Science linking elevated cortisol levels as a potential trigger for mental illness and decreased — especially in .

Cortisol is released in response to or stress by the adrenal glands as part of the fight-or-flight mechanism. The fight-or-flight mechanism is part of the general adaptation syndrome defined in 1936 by biochemist Hans Selye of McGill University. He published his revolutionary findings in a simple 74-line article in Nature, in which he defined two types of "stress" — eustress (good stress) and distress (bad stress).

Both eustress and distress release cortisol as part of the general adaptation syndrome. Once the alarm to release cortisol has sounded, your body becomes mobilized and ready for action — but there has to be a physical release of fight or flight. Otherwise, cortisol levels build up in the blood, which wreaks havoc on your mind and body.

Eustress creates a "seize-the-day" heightened state of arousal, which is invigorating and often linked with a tangible goal. Cortisol levels return to normal upon completion of the task. Distress, or free-floating , doesn't provide an outlet for the cortisol and causes the fight-or-flight mechanism to backfire. Ironically, our own biology — which was designed to insure our survival as hunters and gatherers — is sabotaging our bodies and minds in a sedentary digital age. What can we do to defuse this time-bomb?

Luckily, you can make 5 simple lifestyle choices that will reduce stress and anxiety and lower your cortisol levels:

1. Regular Physical Activity. Kickboxing, sparring, or a punching bag are terrific ways to recreate the “fight” response by letting out (without hurting anyone), thus reducing cortisol.

Aerobic activities, like walking, jogging, swimming, biking, or riding the elliptical, are great ways to recreate the "flight" outlet and burn up cortisol. A little bit of cardio goes a long way: Just 20 to 30 minutes of activity most days of the week pays huge dividends by lowering cortisol every day and in the long run.

Fear increases cortisol. Regular physical activity will decrease fear by increasing your , resilience, and fortitude — which will reduce cortisol. Yoga will have a similar effect, with the added benefit of training.

If your schedule is too hectic to squeeze in a continuous session of aerobic activity, you can reap the same benefits by breaking daily activity into smaller doses. An easy way to guarantee regular activity is to build inadvertent activity into your daily routine. Rding a bike to work, walking to the store, taking the stairs instead of the escalator — these all add up to a cumulative tally of reduced cortisol at the end of the day.

2. Mindfulness and Loving-Kindness Meditation (LKM). Any type of meditation will reduce anxiety and lower cortisol levels. Simply taking a few deep breaths engages the which triggers a signal within your to slow heart rate, lower blood pressure, and decrease cortisol. The next time you feel yourself in a stressful situation that activates your "fight-or-flight" response, take 10 deep breaths, and feel your entire body relax and decompress.

Setting aside 10 to 15 minutes to practice mindfulness or meditation will fortify a sense of calm throughout your nervous system, mind, and brain. There are many different types of meditation. “Meditating” doesn’t have to be a sacred or New-Agey, “woo-woo” experience. People often ask me what kind of meditation I do and how to practice “Loving-Kindness Meditation” (LKM). I am not an expert, but have developed a technique that works for me. I suggest that you do more research, visit a meditation center if you can, and fine-tune a daily meditation practice that fits your schedule and . Below is my daily meditation routine:

Example of Mindfulness and Loving-Kindness Meditation (LKM) method.

I like to practice two types of meditation in one 15-minute session. Personally, I like to use a timer and an “Om” or “Aum” track I have on my iTunes. Some purists might call this "sacrilege," but it works for me, and it might work for you.

To begin, I jot down the names of people I know who are struggling or suffering on a notecard. Next, I set my iPhone to a 15-minute countdown that ends in a harp sound. Then, I sit upright in a chair with my legs crossed at the ankles, set the timer, start the Om/Aum track, and sit with my palms open and facing upwards on my knees.

I begin with a mindfulness meditation of simply focusing on my breath and repeating my "mantra," which is three words that resonate with me. You can choose any word or combination of words that have meaning and significance to you. I repeat these words silently in my mind like a rosary, as I take deep breaths, relax my shoulders, and feel myself drift into a trance-like state.

After a few minutes, I move into the Loving-Kindness Meditation (LKM) phase, which has three steps for me. First, I go through the checklist of specific people I know who are struggling, suffering (or frustrating me), and send them love, light, strength, and compassion. Secondly, I move to universal thoughts of loving-kindness for strangers I may have read about in the news or larger populations that are suffering. Thirdly, as part of the LKM phase, I focus on self-compassion and myself for my "trespasses" and ask for atonement.

After I’ve completed the LKM cycle, I return back to a single-focused meditation, emptying my mind and focusing on my breathing until the alarm goes off. When I hear the harp sound, there is always a Pavlovian-conditioned response of an "ahhh" feeling, accompanied by a big exhale, as I open my eyes and face the real world again.

Remember, you can meditate anytime and any place. is a powerful de-stressor and cortisol reducer that is always in your toolbox and at your fingertips. You can squeeze in a few minutes of meditation on the subway, in a waiting room, on a coffee break.

3. Social Connectivity. Two studies published this week in Science illustrate that social aggression and isolation lead to increased levels of cortisol in mice, which trigger a cascade of potential mental health problems — especially in adolescence.

Researchers at Johns Hopkins established that elevated levels of cortisol in adolescence change the expression of numerous linked to mental illness in some people. They found that these changes in young adulthood (a critical time for brain development) could cause severe mental illness in those predisposed for it. These findings, reported in the January 2013 issue of Science, could have wide-reaching implications in both the prevention and treatment of , severe depression, and other mental illnesses.

Akira Sawa, a professor of psychiatry at the Johns Hopkins University School of Medicine, and his team set out to simulate the associated with the difficult years of adolescence in human teens. They found that isolating mice known to have a genetic predisposition for mental illness during their adolescence triggered "abnormal behaviors" that continued even when they were returned to the group. They found that the effects of adolescent isolation lasted into the equivalent of mouse adulthood.

"We have discovered a mechanism for how environmental factors, such as stress , can affect the brain's physiology and bring about mental illness," said Sawa. "We've shown in mice that stress in adolescence can affect the expression of a gene that codes for a key neurotransmitter related to mental function and illness. While many genes are believed to be involved in the development of mental illness, my gut feeling is environmental factors are critically important to the process."

To shed light on how and why some mice got better, Sawa and his team studied the link between cortisol and the release of . Sawa says the new study suggests that we need to think about better preventative care for teenagers who have mental illness in their families, including efforts to protect them from social stressors, such as neglect. Meanwhile, by understanding the cascade of events that occurs when cortisol levels are elevated, researchers may be able to develop new compounds to target tough-to-treat psychiatric disorders with fewer side effects.

In another study published in Science, French researchers revealed that mice subjected to aggression by specific mice bred to be "bullies" released cortisol, which triggered a response that led to social aversion to all other mice. The exact cascade of neurobiological changes was complex, but also involved dopamine. The researchers found that if they blocked the cortisol receptors, the bullied mice became more resilient and no longer avoided their fellow creatures.

Close-knit human bonds — whether it be family, , or a romantic partner — are vital for your physical and mental health at any age. Recent studies have shown that the Vagus nerve also responds to human connectivity and physical touch to relax your parasympathetic nervous system.

The “tend-and-befriend” response is the exact opposite to “fight-or-flight.” The "tend-and-befriend" response increases and reduces cortisol. Make an effort to spend real face-to-face time with loved ones whenever you can, but phone calls and even Facebook contact can reduce cortisol if they foster a feeling of genuine connectivity.

4. Laughter and Levity. Having fun and reduces cortisol levels. American psychiatrist William Fry has found links to laughter and lowered levels of stress hormones. Many studies have shown the benefits of having a , laughter, and levity. Try to find ways in your daily life to laugh and joke as much as possible, and you'll lower cortisol levels.

5. Music. Listening to music that you love, and that fits the mood you're in, has been shown to lower cortisol levels. I recently wrote here about the wide range of benefits that come from listening to music. We all know the power of music to improve mood and reduce stress. Add reducing your cortisol levels as another reason to keep the music playing as a soundtrack of health and in your life.

Conclusion

President Obama’s second inaugural speech brought up many calls to action that can be framed through the lens of "Cortisol as Public Health Enemy Number One." The ripple effect of a fearful, isolated, and society increases cortisol levels across the board for Americans of all ages. This creates a public health crisis and a huge drain on our economy.

If each of us works alone, and together, to reduce cortisol levels, we will all benefit. As citizens, if we live like we are "All for one, and one for all," we can reduce the amount of stress hormone in our society and individual lives.

Feeling socially connected, safe, and self-reliant reduces cortisol. I hope these tips will help you make lifestyle choices that reduce your levels of stress hormone.

Lastly, in light of the Sandy Hook tragedy, we are all looking for components to a multi-pronged approach that will stop the violence and bloodshed. In my opinion, one way to do this is to create public health policies and funding aimed specifically at reducing cortisol levels in American youth.

In Obama’s speech, he declared, “Our journey is not complete until all of our children, from the streets of Detroit, to the hills of Appalachia, to the quiet lanes of Newtown, know that they are cared for, and cherished, and always safe from harm.” Beyond talk of gun violence legislation, if our legislators and business leaders strive to create policies and fund initiatives that create social connectivity among at-risk teens and reduce , they will be reducing cortisol levels in young people. This should make them mentally and physically healthier, more resilient, and less likely to be violent.