Skip to main content

Raymond Lam

Welcome to Health Advisor, where contributors share their knowledge in fields ranging from fitness to psychology, pediatrics to aging. Follow us @Globe_Health.

I'm a morning person. This time of year I like to watch the dawn arrive while having my morning coffee. It comes slowly, before sunrise, with a gradual increase in daylight over about an hour and a half.

In summer, first light starts before 5:00 a.m. where I live in Vancouver, but a winter dawn doesn't begin until well past 7:30 a.m. That means most people in winter wake up before there is any dawn light outside.

Maybe you have a terrible time waking up on dark winter mornings. If you also have low mood, feel tired all the time and crave carbohydrates, you may have the winter blues. More severe and persistent symptoms that greatly impair your social or work functioning gets you a diagnosis of seasonal affective disorder (SAD), a type of clinical depression. People suffering with SAD are only depressed during the winter and feel "normal" during spring and summer.

A main theory about what causes SAD is that biological rhythms are disturbed by a mismatch between the internal body clock and the external environment. The body clock is situated deep in the brain and is synchronized by light shining into the retina, the layer of light-sensitive cells at the back of the eyes.

The effect of light depends on both the brightness and the timing of light exposure. Outdoor natural light helps our body clock distinguish day from night, and light at dawn and dusk may play a special role to maintain our daily rhythms from summer to winter. The body clock of someone with SAD may not adjust properly to the later dawn signal in winter.

So, could waking up to a simulated "summer dawn" cure the winter blues?

Some winter depression studies have looked at simulating a summer dawn by using a special lamp to gradually brighten over a period of 90 minutes starting at 5:30 am. Even though the full brightness is only at room light levels (300 lux in illumination terms), waking up to a summer dawn may be as effective for SAD as bright light therapy (10,000 lux). The advantage of dawn simulation is that it happens while you are still asleep, unlike bright light therapy that requires you to be awake with your eyes open.

Stores now sell various types of "sunrise clocks" that gradually increase room light to help you wake up, and some even play natural outdoor sounds to enhance the experience. But scientists will tell you that a true dawn simulator requires a more sophisticated computer program and light source (read, more expensive) to ensure the proper gradual increase in light. The research is in early stages, so it's still not clear which is better for dawn simulation.

If you can't afford a sunrise clock or a dawn simulator, try putting your bedroom light on a timer, set for your usual wake-up time. A timer is cheap and most people find it is much easier to wake up into light than into darkness. But will it help your winter depression?

Some SAD studies have found that even a very short dawn pulse, that is, one that is less than 15 minutes from darkness to full brightness, was almost as good as a "real" simulated dawn of 90 minutes, and even as good as bright light therapy.

The dawn simulation studies are still preliminary and results are not yet conclusive, so sufferers of SAD should stick with evidence-based treatments like bright light therapy or antidepressant medications. For those with mild winter blues or who have trouble waking up on winter mornings, a bedroom light timer may be a simple way to bring a summer dawn into your winter life.

For me, I'm up anyway and relying on my morning coffee to help me get past the winter dawn.

Dr. Raymond Lam is a professor of psychiatry at the University of British Columbia and medical director of the Mood Disorders Clinic at the Djavad Mowafaghian Centre for Brain Health in Vancouver. He has written nine books on depression, including A Clinician's Guide to Using Light Therapy by Cambridge University Press. Follow him on Twitter @DrRaymondLam

Interact with The Globe