Find Information About:

Drugs & Supplements

Get information and reviews on prescription drugs, over-the-counter medications, vitamins, and supplements. Search by name or medical condition.

Pill Identifier

Pill Identifier

Having trouble identifying your pills?

Enter the shape, color, or imprint of your prescription or OTC drug. Our pill identification tool will display pictures that you can compare to your pill.

Get Started

My Medicine

Save your medicine, check interactions, sign up for FDA alerts, create family profiles and more.

Get Started

WebMD Health Experts and Community

Talk to health experts and other people like you in WebMD's Communities. It's a safe forum where you can create or participate in support groups and discussions about health topics that interest you.

  • Second Opinion

    Second Opinion

    Read expert perspectives on popular health topics.

  • Community


    Connect with people like you, and get expert guidance on living a healthy life.

Got a health question? Get answers provided by leading organizations, doctors, and experts.

Get Answers

Sign up to receive WebMD's award-winning content delivered to your inbox.

Sign Up

Depression Health Center

Font Size

Tweaking the Body Clock to Ease SAD

Subtle Shifts May Help Patients Handle Seasonal Affective Disorder
WebMD Health News

April 24, 2006 -- Nudging the body's "clock," or circadian rhythm, may help curb seasonal affective disorder (SAD), a new study shows.

SAD is a depression that occurs each year at the same time, usually starting in fall or winter and ending in spring or early summer. The exact cause of SAD isn't known, but the amount of sunlight is an important factor.

The new study included 68 SAD patients. The goal was to see if the medication melatonin could adjust the patients' internal clocks to cope with the later sunrise during winter.

The researchers included psychiatrist Alfred Lewy, MD, PhD, of Oregon Health & Science University.

"Although more studies are needed, these data suggest that most SAD patients might benefit from an appropriate low-dose formulation of melatonin taken in the afternoon," they write.

The study appears in the online early edition of Proceedings of the National Academy of Sciences.

Shifting the Body Clock

Lewy's team gave patients pills containing melatonin -- a hormone triggered by darkness that helps govern the sleep/wake cycle -- or a similar pill without melatonin (placebo). The body's pineal gland makes melatonin; melatonin supplements are also widely available but aren't subject to the same U.S. regulations as prescription drugs.

For three weeks during winter, the patients took a pill every two hours, starting when they woke up and ending four hours or two hours before sleep, for a total of seven or eight daily pills.

The patients were split into three groups. One group received melatonin in the morning and a placebo the rest of the day; another group got placebo in the morning and melatonin in the afternoon. The third group took placebo pills at all times. No one knew which pills contained melatonin.

The pill schedule and doses were based on the theory that "most SAD patients become depressed in the winter because of the later dawn," the researchers write, calling melatonin "the chemical signal of darkness."

Lewy and colleagues checked the patients' depression severity before treatment and every week during the study.

Soothing SAD

The researchers found that in most patients SAD was linked to delayed sunrises. Those patients tended to respond best when they got melatonin in the afternoon. Afternoon melatonin shifted their body clock to earlier in the day.

Today on WebMD

Differences between feeling depressed and feeling blue.
jk rowling
Famous people who've struggled with persistent sadness.
depressed man sitting on hallway floor
Learn the truth about this serious illness.
Sad woman looking out of the window
Tips to stay the treatment course.
unhappy teen boy
Health Check
jk rowling
Pills with smiley faces
Teen girl huddled outside house
Depressed man sitting in hospital hallway
antidepressants slideshow
pill bottle
Winding path