Bright light treatments may help lift people from the depths of severe winter depression, but new research suggests that timing these treatments to the body's internal clock may improve light's antidepressant affect.

The results of the study suggest that:

Light has its most antidepressant effect if used early in the morning.

Light therapy, a treatment for seasonal affective disorder (SAD), can alter the body's internal clock

Therapy sessions timed to match an individual's circadian rhythm, or internal clock, can be twice as effective as those applied later in the morning or in the evening. There's a direct neural connection from the retina in the eyes to the site of the biological clock in the (brain). The biological clock resets depending upon the pattern of daily light exposure.

As many as half the people in the middle and extreme latitudes of the earth feel at least mildly depressed with seasonal changes. In the US, 6% of these experience the more severe symptoms of depression known as seasonal affective disorder (SAD).

Light therapy, however, can trick the brain into thinking it is spring or summer instead of fall or winter.

Melatonin is the hormone in the animal kingdom that (alerts) the nervous system the season of the year. As night length grows longer the melatonin secretory episode also grows longer, and that's what puts our brain and body into a winter state.

The investigating team found that 30 minutes of intense, bright light (with no ultraviolet radiation) about 2 to 3 hours after the midpoint of sleep produced the best antidepressant results.

In fact, light timed to this point in the circadian cycle actually doubled the effectiveness of the therapy as compared to sessions in the evening, a time when melatonin begins to be released. SAD patients who underwent the early morning light therapy sessions had an 80% chance of sending their depression completely into remission.

"There's an optimum circadian time, internal time, for the administration of light therapy in order to achieve the antidepressant affect for SAD. The pattern of light exposure is the critical event to that synchronizes the internal clock to the external world.

Archives of General Psychiatry; January 15, 2001; 58; 69-75

Dr. Mercola's Comments:

Most are familiar with the benefits of light for treating SAD, but this article is useful as it provides valuable information on the timing of the light. Previous research has shown that even shining light on the back of the knee can be helpful at restoring natural biorhythms. SAD and winter depression are especially prominent during the winter months, as most of the regions we live in suffer from a severe deficit of sunlight. Therefore, in order to fill this sunlight void and effectively avoid depression, I highly recommend using Bio-Pure Light Boxes -- now available on my "Recommended Products" page. Bio-Pure Light Boxes contain light bulbs that project full spectrum sunlight. You see, in order to achieve natural balanced sunlight INDOORS it is important that your light bulbs contain a full spectrum of color, as well as infrared and ultra violet wavelengths. There are two models you can chose from (BP-12 Combo Box and BP-12 Junior), which contain these essential ingredients to help you obtain the balanced sunlight that is essential to your physical AND mental health. In addition, the study provides an elegant confirmation that early morning risers tend to do far better with depression. I have long encouraged people to get to bed early in the winter so they can get up early. Apparently the early arising exposes one to light that is closer to being synched with natural biorhythms. This will provide powerful normalizing forces for the adrenal glands, which control many of our hormone systems through delicate feedback mechanisms. And, with that in mind, I am excited to present The Sun Alarm™ SA-2002, which provides an ideal way to wake up each morning if you can’t wake up with the REAL sun. I use this clock to wake up each morning -- not the typical alarm clocks which “startle” you out of sleep, a very unhealthy way to start any day. Combining the features of a traditional alarm clock (digital display, AM/FM radio, beeper, snooze button, etc) with a special built-in light that gradually increases in intensity, this amazing clock simulates a natural sunrise. It also includes a sunset feature where the light fades to darkness over time -- ideal for kids or anyone who has trouble falling asleep. Related Articles: Light Treatment in Morning Best For SAD Seasonal Affective Disorder Hits Children Full-Spectrum Light Winter Depression Sufferers See The Light