Sarah Brengarth doesn’t want to get out of bed. She looks outside the window in her room and sees it’s cloudy again. The 40-degree temperature completes the dreary morning.

Brengarth, Columbia, Mo., junior, just wants to stay inside and sleep. She is one of many people affected by the changing weather.

Steve Ilardi, associate professor of psychology, said about one in every three Americans felt the effects of the winter blues. If the feelings persist, he said, these people could fall prey to seasonal affective disorder, a type of depression brought on by the changing weather.

The impending winter’s most influential factors are the decrease in sunlight and the drop in temperature, Ilardi said. These changes affect the functioning of the brain and throw off the body’s internal clock, called the circadian rhythm. Ilardi said our brain notices the differences in light intensity and resets our body clock according to a 24-hour cycle.

“It’s not a Timex,” Ilardi said. “It needs to be reset every day.”

Ilardi said if the body’s clock wasn’t reset, there tended to be negative consequences. The personal costs of the changing season include drops in energy levels, negative moods and trouble sleeping. Ilardi said the quality of sleep also declined, becoming less restorative. He said the lack of sleep could bring on the full effects of depression.

Bret Jones, Topeka senior, said he tended to snuggle up with his Xbox when it was too cold to go outside. Usually an active person, Jones said his level of physical activity dropped drastically during the winter months.

The decline in physical activity is common from December through February, Ilardi said. He said the colder temperatures kept people from spending time outside, the consequences of which were two-fold. Ilardi said physical activity was a potent anti-depressant. A lack of activity makes people more prone to depression. Along with reduced activity, Ilardi said staying inside robbed people of an important part of their health: sunlight.

The sun helps the body in many important ways. Ilardi said exposure to sunlight stimulated brain circuits that produce serotonin and dopamine, essential brain chemicals. Dopamine, a chemical used mainly in the pleasure centers of the brain, helps keep people more alert and energetic. Ilardi said people reported “a sensation of raw pleasure” when outside on a sunny day. The other chemical, serotonin, plays a soothing role, reducing stress reactions in the brain.

Ilardi said sunlight also helped the skin make vitamin D, a nutrient vital to brain function. He said by the end of winter, 80 percent of Americans suffered from a vitamin D deficiency. The Mayo Clinic Web site said vitamin D was crucial to maintaining healthy bones as well as helping prevent certain cancers and high blood pressure.

Ilardi said the various factors that could contribute to depression during the winter were relatively easy to avoid. He said students could spend 30 minutes outdoors on reasonably bright days or take vitamin supplements to battle deficiency. He said students should aim to sleep about eight or nine hours to be fully rested. Ilardi said these strategies could help students avoid feeling down.

Jones said he generally managed to get enough sleep during the semester, averaging about seven hours each night. Ilardi said avoiding sleep deprivation was paramount, and that more than 80 percent of depression cases list a lack of sleep as a contributing factor. He said figuring out if a person was getting enough sleep was simple. He said yawning or getting drowsy when bored was an indication of sleep debt.

“Look at what happens to children,” Ilardi said. “They get enough sleep and they get restless, not sleepy. The vast majority of students should take that difference as a sign.”

— — Edited by Becka Cremer