Why Warm Weather and Hot Tubs Make Us Happy

Source: morgueFile

Lying on a sunbaked beach or soaking in a hot tub can lift your mood – but how? There’s good evidence that physical warmth has an antidepressant effect. In fact, researchers are testing whole-body heating chambers as a possible treatment for major depression. You may be able to reap some of the same benefits by simply stepping outside on a warm day.

One of the leading experts in this fledgling field is Christopher Lowry, PhD, Associate Professor of Integrative Physiology and a member of the Center for Neuroscience at the University of Colorado Boulder. Recently, I had a chance to chat with Dr. Lowry about the connection between feeling physically warm and feeling more upbeat. Here’s what he told me.

How do warm temperatures affect someone’s mood?

Dr. Lowry: Exposure to warm temperature stimuli that aren’t painfully or unpleasantly hot can elevate a person’s mood. This has been observed in clinical settings. And it also happens in the spring, when the onset of warm weather after a cold winter helps account for the mood lift seen in “spring fever.”

The key physiological mechanisms underlying this effect aren’t certain yet. However, we believe that warming of the skin increases electrical signals in sensory neurons. These neurons relay signals to the spinal cord, and neurons in the spinal cord then pass along the signals to the brain.

The result is activation of brain areas that process pleasant stimulation, such as the medial orbitofrontal cortex. Activity in the medial orbitofrontal cortex is low in depression, but it’s increased by warm stimulation in a way this is correlated with perceived pleasantness. Simply put, warming the skin makes people feel good emotionally.

Could this be useful in the treatment of depression?

Dr. Lowry: I believe that there are potential benefits to the use of infrared whole-body heating in a clinical setting. This involves heating a person’s body to a warm temperature in a heating chamber. The only part of the body that remains outside the chamber is the person’s head.

Infrared heat waves are ideal for this purpose, because this type of heat radiation doesn’t penetrate deeply into the body. Instead, it heats primarily the skin. Consequently, exposure to heating can be prolonged without elevating a person’s core body temperature, which could be dangerous.

My colleagues and I are currently collaborating with Dr. Charles Raison at the University of Arizona, Tucson, on a double-blind, placebo-controlled clinical trial of whole-body heating in patients with major depressive disorder. Who knows? Maybe someday psychiatry clinics in the United States will offer whole-body heating as a treatment option for major depression or other psychiatric disorders. That’s already the case in some clinics in Switzerland.

What about the more ordinary ways that people get warm — for example, by soaking in a hot bath, stepping outside on a warm day or snuggling under a blanket on a chilly night? Do they help?

Dr. Lowry: These methods of warming up in everyday life are likely to be effective strategies for giving your mood a little boost, at least transiently. However, they are unlikely to induce the type of long-term changes in the brain that would be required to bring lasting relief to patients with major depression.

Linda Wasmer Andrews specializes in writing about the mind-body connection. Follow her on Twitter and Facebook. Read more from her blog:
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