Conversely, a bad environment can hamper your functioning and even reinforce negative behaviors like addiction. Consider the case of heroin addiction among US soldiers in Vietnam.

Heroin Addiction Among U.S. Servicemen

In the 1970’s two congressman reported to Nixon that 15% of U.S. servicemen in Vietnam were addicted to Heroin. In itself, this finding is not particularly striking. War is extremely stressful.

Here's the crazy part. The number of soldiers who relapsed to heroin use upon returning to the states was only about 5%.

So 95% of the American heroin addicts in Vietnam did not become re-addicted when they returned to the States. And heroin is among the most addictive euphoriants known to man (along with tobacco).

The takeaway is that our environment unconsciously sculpts our behavior. Context is key.

Environmental Context and Drug Tolerance

Context also affects drug tolerance at the neurobiological level.

Consider someone who typically self-administers heroin in the bathroom. But now let's say that they take their usual dose of heroin in a difference context - their friend's house. This time, they experience a lethal overdose. Why?

One theory is that the brain begins to associate the bathroom with heroin use. This is your run-of-the-mill case of Pavlovian pairing of stimuli.

Pavlov's dogs with handlers

So we can imagine that when the heroin user enters the bathroom, their brain begins to compensate by down-regulating opioid receptors. The brain "expects" to receive heroin in this context based on past experience. And so tries to correct in advance, increasing its tolerance to the poison. But in a new context (like your friend's house) this compensatory response is thwarted.

If the same amount of a drug is administered in one context and later in another different and distinct context, then the effects of the drug are different," Cepeda-Benito says. "The drug has a much greater effect in a novel context rather than in a context that is associated with the administered drug.

Here are a few habits / behaviors I’m committed to testing out to inject some novelty into my environment.

1) Cold Showers

Please keep your eyes open in the shower

I was initially reluctant to test out this idea because, well, cold showers are a bitch.

People have varying levels of tolerance to cold, and I’m at the cold intolerant end of the spectrum. I have low-grade, subclinical hypothyroidism which makes it more difficult to tolerate the cold. But a friend was espousing the benefits of cold showers, and after doing some of research, I had to try it.

Whole-body exposure to cold water is expected to send a tremendous amount of electrical impulses from periphery the brain. A cold shower delivers a massive stimulus to the brain that resembles electroconvulsive therapy without the undesirable side effects (like seizures).

A lifestyle that lacks certain physiologic stressors - such as brief changes in temperature - may hinder brain function.

Exposure to cold activates the sympathetic nervous system. This has two effects: (a) increased catecholamine release, and (b) increased beta-endorphin which is the endogenous opioid. Endorphins also play a role in the antidepressant effects of exercise.

Hormesis is a phenomenon where small amounts of a harmful agent can be beneficial for health. An acute stressor triggers a compensatory increase in the functioning of repair/recovery systems. For example, exercise induces harmful reactive oxygen species (ROS). These ROS trigger an adaptive increase in antioxidant defense, which is net-beneficial.

Brief whole-body exposure to cold water is safe and has negligible effect on core body temperature 23.

Here was my regimen:

One ten-minute cold shower every other day. As someone who is relatively cold-intolerant, I had to work up to ten minutes. The biggest benefits I noticed were:

An easier time waking up in the morning

Shivering (no kidding!)

A mood boost that was analogous to the runner's high

2) Intermittent Fasting

Another habit I'm embracing in 2017 is intermittent fasting.

Researchers once noted that mice with restricted caloric intake live longer. Ever since, humans have been studying the relationship between fasting and life extension.

Caloric restriction, undernutrition without malnutrition, is the only experimental approach consistently shown to prolong survival in animal models.

But this consensus about the longevity-promoting effects of calorie restriction (CR) are not unanimous. Most evidence comes from animals and cannot be neatly translated to humans (See: Health effects of intermittent fasting: hormesis or harm? A systematic review) .

Here's the take-home message on intermittent fasting:

Like cold showers, intermittent fasting is another example of eustress. The prefix eu is of Greek origin and means "well" or "good." Hence, eustress is beneficial stress (in comparison to chronic, unpredictable stress which is harmful). Intermittent-fasting is eustress (mild stress) that induces a hormetic compensation.

Practical tips

I fast for 12 hours once a week. This is pretty minimal - there are people of there who regularly skip meals for days.

Your ability to tolerate hunger increases over time and with practice. If you have difficulty resisting the temptation to eat, it can help to keep your mind occupied.

3) Early-Morning Bright Light Therapy

No arbitrary stock photo meant to exemplify sunshine is complete without a pretty girl.

Most humans spend the majority of their time indoors, shielded from the sun.

But we need sunshine to entrain our biological clock and synthesize vitamin D. Sunshine is an antidepressant, and many people with seasonal affective disorder are not getting enough light 5.

An advantage of early-morning bright light therapy is that it calibrates your circadian rhythm without exposing you to much UV radiation. One day in the sun is comparable to about 1/6 of the typical dose of radiation delivered by an x-ray.

Fun fact: The Banana Equivalent Dose Curiously enough, the Banana Equivalent Dose (BED) is a unit of ionizing radiation exposure. It reflects the dose of radiation delivered by one banana. Bananas naturally contain potassium-40 - a radioactive isotope of potassium. One BED is frequently taken as 0.1 µSv. In practice this dose is not cumulative because potassium-40 is excreted to maintain metabolic equilibrium.

Parting Words

Environmental novelty is a concept in neuroscience that has received a lot attention because it helps animals thrive. You can apply this in your life by switching things up.