”There was a desert wind blowing that night,” wrote mystery writer, Raymond Chandler in ”Trouble is My Business” (1934). ”It was one of those hot dry Santa Anas that come down through the mountain passes and curl your hair and make your nerves jump and your skin itch. On nights like that every booze party ends in a fight. Meek little wives feel the edge of the carving knife and study their husbands` necks. Anything can happen.”
Literature and folklore simmer with stories of how escalating temperatures fuel escalating passions. But can sweltering heat really provoke people to rape, murder and pillage? Can the dog days of summer drive you crazy?
Well, no, not exactly. But the evidence is mounting that, despite our climate-controlled habitats, the human animal remains remarkably sensitive to the elements. And while scientists argue about the extent of weather`s influence on health and behavior, many blame summertime heat for a variety of troubles from depression to crime.
Experts have long recognized that the dark winter months leave some people depressed. Now researchers are investigating the flip side of winter blues: summer depression.
”This is a genuine depression,” says psychiatrist Thomas Wehr of the National Institute of Mental Health. Summer depressives score high on diagnostic tests and improve with antidepressants-two telltale signs of true depression, says Wehr, who is one of the first to describe the condition in 1986.
The difference between general depression and the summer variety seems to be timing and location. Summer depressives become severely depressed in late spring, yet are symptom-free as winter approaches. And the farther south they travel, Wehr says, the greater their risk. Conversely, traveling north lessens the symptoms.
Seasonal depression is hardly new. The ancient Greeks believed the environment influenced much of human illness and blamed the weather for several diseases. Many 19th Century psychiatrists wrote about seasonal depression and prescribed travel to different latitudes for their wealthy clients.
While the mechanisms of summer depression remain a mystery, Wehr and others suspect that temperature and light play important roles.
”Our bodies are very tuned to changes in heat and light,” Wehr says, speculating that early human survival depended on adapting to seasonal changes to conserve emotional and physical energy.
”Some people may have extreme reactions to climate,” he says. ”The brain mechanism that responds to the environment may be disordered in people prone to seasonal depressions.”
Wehr has experimentally treated some summer depressives by modifying temperature and light. Patients wear sunglasses, soak in cold baths and rest in cool, dimly-lit rooms. Most of his patients said their symptoms eased in 4 to 5 days.
More recently, Wehr is looking at how changes in light and heat may affect the thyroid gland. In normal people, thyroid function slows in summer. But in summer depressives, the gland may be particularly sluggish.
Several studies have shown that depressed people often lack the normal nighttime surge of a brain chemical that stimulates the thyroid gland. The challenge now, Wehr says, is ”to see if changes in temperature and light can alter thyroid function in summer depressives.”
Even people who suffer from nonseasonal depression, may find summertime heat and humidity makes their disorder worse. Researchers at the University of California at Davis found an increase in emergency-room visits for depression on days when the barometric pressure was low. And more schizophrenics found their way to emergency rooms during days of high air pollution.
”We picked up complex and subtle relationships between the weather and psychiatric diagnoses,” says Dr. James Spensley, a researcher on the study. He speculates that weather and pollution may affect specific brain chemicals of psychiatric patients.
There is less evidence that hot weather leads to criminal activities, even though such a notion is firmly embedded in the public`s mind.
According to the law
This idea probably dates back to the late 19th Century, when a French criminologist named Quartelet first speculated that climate influenced crime rates. Analyzing crime statistics, he accurately predicted that assaultive crimes were highest in the south of France or during the summer, while property crimes increased in the north of France or during the winter.
Today, U.S. crime rates seem to follow ”Quartelet`s Thermic Law of Delinquency”: armed robberies peak in the winter and aggravated assaults, including rapes, are greatest in the summer.
But whether heat is responsible is less clear. Psychologist Paul Bell of Colorado State University says assaultive crime sometimes increases as the mercury climbs past 90 degrees. But sometimes the opposite is true.
No one is quite sure what to make of the mixed statistics. Bell, who has studied assaultive behavior ”under laboratory conditions,” suggests that
”most people would rather flee than fight when it gets hot. But if they can`t flee, they will fight.”
FBI consultant Dr. Park Dietz, a criminologist and psychiatrist at the University of Virginia, says the number of aggravated assaults does peak during the summer nationwide, but the trend is less convincing within individual cities.
Dietz suggests that the summertime national increase in violent crimes, such as rape, has less to do with heat than it does with ”greater rates of social interaction, or more people getting together in the summer, especially on weekends.”
Geographer Keith Harries of the University of Maryland`s Baltimore County campus says homicide rates have been higher in the South since national crime rates were first recorded. But this murderous trend may have more to do with longer daylight hours and social conditions than with temperature.
Based on assault rates in Dallas from 1980 to 1985, Harries found heat had a ”marginal effect” on crime. The day of the week, economic status and the use of alcohol seemed more significant, he says.
And does crime increase when there are hot summer winds like the Santa Ana? ”We are not aware that homicide increases during the Santa Ana wind,”
says a spokesman from the Los Angeles Police Department. ”We don`t even keep statistics like that.”
But hot, dry winds have been linked with increased mental hospital admissions, heightened irritability and problem-solving difficulties, according to environmental psychologist James Rotton of Florida International University.
Rotton and others speculate that such winds may decrease the number of negatively charged particles in the air. Preliminary studies suggests that a drop in negatively charged ions may adversely affect mood.
Not everyone is convinced that the weather significantly affects behavior. Psychologist George Banziger of Marietta College in Ohio thinks that ”unemployment and family stresses have more to do with mental health and stability than the weather.” Weather can be stressful, he concedes, but
”it`s at the bottom of the list.”
Regardless of heat`s position on the stress list, says psychiatrist Alan Levenson of the University of Arizona, ”heat does tend to be a source of frustration for many people. And while it`s not the primary cause, it can be the final straw in exacerbating problems that already exist.”
Heat may not fuel passions or cause crime, but it seems that summer temperatures do influence behavior. Despite our air-conditioned cars, houses and offices, our swimming pools and icemakers, summertime heat continues to take its toll. And as the experts debate weather`s influence, one thing is clear during the summer of 1989: We still haven`t beaten the heat.
