The physical and psychological effects of "HEAT STRESS" is well documented.
As the U.S. and Canada enter into a heat wave, I get a lot of questions about how heat impacts human behavior and our moods. So three years ago, I wrote a blog entry that reviews the research about weather affects our moods and behavior. It’s still a good overview of the research in this area and worth the read.
But it’s nice to highlight a few points from that article, as well as other research, that demonstrates how the weather — and especially hot weather, in this case — can impact our mood. Does a heat wave lead to more violence? Do we have more or less energy during high humidity? What about depression and anxiety?
Read on for the answers.
Heat waves come and go nearly every year in some part of the world. What makes them especially difficult for indigenous populations during the summertime is that the farther away you are from the equator, the less experience you have with dealing with hot weather. So a slew of 100o F days in Houston, Texas is generally no big deal. But string a few of them together in Vancouver and suddenly it’s an issue.
A few of the findings from the research stand out:
- Heat waves are related to more violent behavior and aggression
- Heat waves may be associated with higher drug and alcohol abuse
- Anxiety tends to decrease with a rise in temperatures
- Depression and lowered mood tends to increase with a rise in temperatures
- High levels of humidity — which often accompany a heat wave — lower concentration
- High humidity also increases sleepiness (probably related to poor sleep)
- High humidity also appears related to a lack of vigor and energy
If you see a pattern in the above list, you’re not alone. If high temperatures are accompanied by high humidity (as they often are in a summertime heat wave), people have more trouble sleeping (Okamoto-Mizuno, et al. 2005; keeping in mind, not everyone has an air conditioner). Less sleep or a poorer quality sleep over a number of consecutive days causes all sorts of problems in life — including lower concentration, less energy, and even a depressed mood.
The AP also points out that there are greater concerns for older people in hot weather too:
There are changes in an older person that raise the risk for heat stroke and other problems. An older body contains far less water than a younger one. Older brains can’t sense temperature changes as well, and they don’t recognize thirst as easily. [...]
Heat exhaustion can cause muscle cramps, low blood pressure, rapid pulse and nausea. It can be treated at home, by drinking water, getting into an air-conditioned room or sitting in front of a fan and misting the body with cool water.
Also, we need to keep in mind that the medication you take may also negatively affect your body’s ability to cope with higher temperatures:
Medicines many older people take also may make them more vulnerable to the heat. These include diuretics for high blood pressure, which increase urination – and make it more important to drink plenty of water, Dale said.
Some types of drugs can interfere with sweating and raise body temperature, including some medicines for insomnia, nausea, prostate conditions, Parkinson’s disease and even Benadryl. Many list “dry mouth” as a side effect – a tip-off to drink more water, Zich said.
Just because the heat didn’t used to bother you when you were young doesn’t mean you should ignore your body’s warning signs when it’s getting more and more dehydrated in hot temperatures.
What You Can Do in a Heat Wave to Help
So given all this, what can you do to minimize the negative side effects of a heat wave?
- Minimize the time outside in hot temperatures. Put off running any errands or trips outside the house that can wait until the heat wave breaks.
- If you don’t have air conditioning, seek out friends or family who do. Remember you can spend a lot of time in quasi-public places, like a Walmart or other stores, the local shopping mall, library, senior center, or similar kinds of places that offer air conditioning.
- If no air conditioner, minimize your indoor temperatures by keeping your blinds or curtains mostly shut, especially southern-facing windows.
- If you can’t afford an air conditioner, make sure you at least have one or two fans, and drink plenty of water. If you normally drink 2 or 3 glasses of water a day, try to get up to 8 or 12 glasses. Staying hydrated is the most important thing you can do.
- Talk to your doctor about the dehydrating effects of yourmedications.
- Look at the lifestyle of people who live closer to the equator and consider taking a mid-afternoon siesta or nap to help get through the hottest portion of the day.
- Avoid making any big life changes during a heat wave, especially anything that might be emotional or especially challenging in your life.
- If you’re a loner, a heat wave is the ideal time to make new friends who have air conditioning.
- If you’re feeling dizzy or odd, call 911 or emergency services right away.
Heat waves are a normal part of life in most parts of the world. You don’t have to worry about them too much as long as you’re sensible, take things especially easy, and don’t make any big plans for things to do or change in your life. Stay out of the sun and in the shade, and stay indoors in air conditioning as much as possible to limit the negative effects of the heat wave on your own mood and behavior.
Physical effects of HEAT STRESS are delineated here:
The Physiological Effects of Heat Stress
Adverse effects of elevated body temperature
Hyperthermia is a situation in which the actual body temperature is higher than your body’s “basal metabolism”, which is when the body is at idle. It can occur as a response to heat exposure if you cannot get rid of the heat that you are absorbing from the environment as well as the heat you are producing yourself. Your body attempts to return its temperature to the “basal metabolism” set point.
There are several health problems that can develop if your body is not able to deal effectively with Hyperthermia.
An extended elevated body temperature will eventually result in tissue damage, much like the situation when a mother has a child with a 105° fever.
People that experience heat stress also develop aggressive behavior. In a factory situation, this can lead to other serious problems in the workplace, especially with other workers who are also starting to feel the effects of the heat.
Recklessness is another symptom that develops. The affected worker no longer has the same level of patience that he or she usually exhibits, and cannot deal as effectively with small problems. This leads to unnecessary accidents, which in turn, can create some far-reaching problems.
Performance also slows down. The body begins to compensate for its immediate problem of too much heat when the brain receives the heated blood. As body temperature rises, the brain sends out instructions to decrease the muscle tone. Individuals may feel tired and listless, and not able to work as well. Not only does production suffer as a result, but also the individual feels more of the burden of work. It becomes increasingly harder to perform their regular tasks.
The health problems that result from heat stress can be serious. They include:
Heat Stroke, which is, by far, the most serious. 1700 people in the U.S. died of heat-related causes during one year. The mortality rate where individuals do not know how to handle this medical emergency can be upwards of 50%. It’s that serious.
Heat Syncope, which is fainting from exposure to heat.
Another is Heat Edema, which usually happens a day or two after the individual enters into a hot environment. Heat Edema is the result of the body not able to dump the salt and water it is ingesting, and usually shows up as ankle swelling.
Heat Cramps is another problem, which is a result of not enough salt.
Another major health problem is Heat Exhaustion. In this case there is no sensation of thirst – usually because they have been drinking water already, but not enough. The person exhibits headaches, nausea, vomiting, weakness, and anxiety.
We have a constant input of heat into our bodies and if we’re going to stay healthy, we have to have a constant output. If we don’t have this output, we develop heat injuries.
Working in the heat
When you are working in the heat, there will be increased blood. Exercising muscles require more blood, and, when you exercise, your muscles heat the blood. The heated blood reaches the brain and tells the hypothalamus to cause skin vessel dilation and sweating. Heat loss then happens through the mechanisms of direct convection heat transfer from the body to the environment and from the evaporation of moisture from the skin.
As a rule, there is not enough blood volume to supply all the little skin vessels and capillaries in order to attempt to dissipate the heat loss. The solution is to take in fluids to increase the volume. Often, however, this is not enough.
The average individual may lose one to two liters of fluid without much decrease in performance. When you become more dehydrated, however, your blood volume decreases and you cannot get rid of the heat load fast enough. You just don’t have enough blood volume to supply the skin vessels for sweat production. As a result, the body temperature begins to rise disproportionately as you become more dehydrated.
Getting Rid of Heat
People who perform hard, physical work have two basic problems.
First is the amount of heat that their bodies produce because they are working. Second, they are going to absorb heat out of the environment. Heat lost from the person must equal the heat gained from the environment along with the heat the body produces from work. The problem is to maintain the heat balance of the worker.
Basal metabolism, when you are not doing any work, produces 65 to 85 kilocalories/hr (like idling a car). If you are just sitting at rest, the rate of rise form basal metabolism you normally produce per hour, will be about 2°F/hr. If you work hard, you raise your body temperature at a rate of 9°F per hour. Doing heavy labor will generate up to 570 calories per hour. Outside heat is added to that, i.e., sunshine alone adds 150 kc/hr. There’s only so much a worker can handle before he must find some way to get rid of that extra heat. You can not stay in that environment very long. You must get rid of the body heat build-up.
The physiologic mechanism for eliminating heat is through the evaporation of water, the evaporation of sweat. Sweating is called upon when the physical means are no longer capable of eliminating heat, and our insensible water loss can’t keep up with production in the body. Evaporation, or sweating, accounts for roughly 22% of the total heat loss from the body. You can lose one kilocalorie for each 1.7 cc of sweat.
To handle a lot of heat requires the intake of a lot of fluids. The stimulus for thirst as a rule is not enough to replace the body water loss. Those of you who work in factories know that you must almost force workers to drink enough water. Compound that problem with the fact that when air temperature exceeds 80°F, the body does not effectively lose heat by convection, or the evaporative cooling of the skin. One actually begins to gain heat from the environment.
Simplified, work environments that are hot will create serious health problems for workers. That, in turn, will also create economic loss for the company. Relying on the human body to compensate is not enough. Hoping that the workers will take necessary precautions is not enough, either. Care and good planning is absolutely necessary to prevent the types of multiple problems that heat can create. There are several approaches that can be taken, and all of them should be taken into consideration.
We offer one solution with our Magic Cool Bandannas. These bandannas give an external source of moisture to create an evaporation cooling process right at the most vulnerable point. They can’t cool the air, but they can cool the blood and the spinal column. This product is not designed with an “R” factor in mind to retain coolness. Rather it enhances the same powerful evaporative process the body already employs. It also applies that cooling process right where it will be most effective, on the neck.
It is not the only solution to Relief from the Heat, but is certainly one of the most cost effective, easily employed, and directly applied that there is.