BUFFALO, N.Y. (WIVB) — Feeling sluggish and down lately?

Seasonal Affective Disorder (SAD) is a type of depression linked to the changes of the seasons. According to Mental Health America, it impacts about five percent of the U.S. population.

“Seasonal affective disorder is a very well-characterized condition that consists of depression – generally in fall or winter, and people feel totally well or sometimes more “revved up” in spring and summer,” said Dr. Steven Dubovsky, chair of the University at Buffalo Psychiatry Department.

SAD is distinct from people who have year-round depression that worsens in the winter months, he added.

“It’s related to hibernation – everything slows down during the winter when there are scarce resources, versus in the summer when you go out and forage,” Dr. Dubovsky said.

Seasonal depression symptoms include sleeping a lot, eating more, craving carbohydrates and sweets, feeling sluggish and losing interest in things.

Typically, the further away you are from the equator, the earlier SAD starts and the longer it lasts.

“At this latitude, generally people start developing seasonal affective disorder in mid- to late September and it tends to last generally until March or early April,” Dr. Dubovsky said. “If you go a little further south, it starts later and goes away sooner.”

South of the equator, the pattern is reversed as their “winter” season starts around June.

The culprit is a lack of daylight, which messes with your bodily rhythms.

Sunlight – either real or artificial – can help to cure SAD.

Daylight lamps with a brightness of 10,000 lux – about as bright as real daylight – can be purchased for treatment at home. You’ll want the light to get in your eyes without looking directly into it, so Dr. Dubovsky suggests setting it about three feet away from you while you eat breakfast or do other activities. The average person will need about 30 minutes a day with the lamp.

You can also go out in the natural sunlight to get the effect.

Dr. Dubovsky says you’ll want to get your light therapy first thing in the morning when you wake up.

“The best cue for the time you fall asleep is exposure to bright light at the time you wake up,” Dr. Dubovsky explained. “If you have exposure to bright light at 8 a.m. in the morning, your brain says ‘I should wake up at 8 a.m. and go to sleep at midnight to get eight hours of sleep.”

Kaley Lynch is a digital reporter who has been part of the News 4 team since 2017. See more of her work here.