Spending more time in the sun to improve your circadian rhythm health may also improve your vitamin D status, but the bright-light treatments that are at the heart of modern treatment of circadian rhythm disorders will not increase the vitamin D in your bloodstream. Not only is your biological clock set by light
hitting your eyes—not your skin—but the kind of light your body prefers for calibrating its clock is early-morning light. At this time of day, too little UVB radiation is penetrating the atmosphere to also get a good dose of vitamin D.
In addition to scheduling morning exposure to sunlight to help keep the biological clock ticking in time with the twenty-four-hour day, one of the most common methods used today to address circadian rhythm disorders is the light box. Light boxes emit up to 10,000 lux (a measurement of light intensity) and mimic natural sunshine at around noontime. The light emitted by these devices is twenty times the intensity of average indoor light (500 to 1,000 lux), which, most people are surprised to find out, is only as strong as the natural twilight.
The light boxes themselves consist of a set of fluorescent bulbs installed in a box with a diffusing screen that spreads the light evenly and filters out all UVB and most UVA radiation. Using a light box is easy. You simply position the box on a nearby table or desktop and sit comfortably for the treatment session. It’s imperative to sit or stand close to the light box, with or without the room lights on, and your eyes must be open. Looking directly at the lights is unnecessary;
instead, light-box users pass the time reading, writing, watching TV, or eating a meal. The only reported side effects are occasional slight headaches. The duration of bright-light treatment sessions varies from fifteen minutes to three hours a day, depending on your individual needs and the equipment you use. The more powerful the unit, the less time you have to spend in front of it to get the same effect. Also, the nearer you are to the light source, the higher the intensity of light shining through your eyes and the quicker and more effective the treatment.
The timing of light treatments is extremely important and varies with each person, depending on the type of circadian rhythm disorder being addressed.
People who have late-night insomnia, for example, and thus have trouble getting up in the morning after going to bed too late, may only need one brief treatment a day in the morning to speed the body clock up; those with early-morning insomnia have the reverse problem—they wake up too early and fall asleep in the early evening. These people need to slow down their body clocks and can typically do so with early evening sessions of bright-light therapy to avert their superearly bedtimes and align their bodies with the twenty-four-hour day.
Knowing exactly what kind of rhythm disorder you may have and then scheduling the right kind of light therapy is important, and this reinforces the need to use bright-light treatment under the supervision of a qualified sleep therapist.
You don’t need a prescription for a light box, but anyone suffering from a serious mood-related disorder should certainly seek a doctor’s recommendation before obtaining a unit and use it under the doctor’s supervision. Choose your doctor wisely, and question one who only prescribes drugs such as sedatives or antidepressants for your condition. Some doctors are unaware of the successful results of bright light therapy.
Several reputable companies sell light boxes (see the Resource Guide on page 269). The key to successful bright-light treatment is using a product that provides strong light at a reasonable unit-to-user distance. It is important that you purchase your light box from a trusted company, because there’s no way you can measure the lux output of a bright-light unit. If your symptoms don’t improve, you won’t know if it is because the inexpensive light box you bought is not emitting strong enough light or because your condition is resistant to bright-light treatment. Tests of products sold by disreputable companies demonstrate that certain light boxes don’t put out the amount of light they are advertised as emitting. Also, poor-quality screens may not filter out enough UV radiation, which may damage your eyes. A portable unit might suit you if you travel a lot, or one with a stand may fit your needs if you plan to get bright-light treatment while working out on a treadmill or stair climber. Numerous accessories are also available, including padded carrying cases and stands that let you place the light box in different positions. These units can cost between two hundred and seven hundred dollars, depending on a variety of factors, the most important being the unit’s lux output and the distance it can project that light intensity. Many insurance companies will reimburse the purchase price of light fixtures for the treatment of seasonal affective disorder, PMS, and sleep disorders.
Seasonal Affective Disorder (SAD)
If you live at a higher latitude, you are probably aware of some minor changes in yourself that accompany the lengthening days of late fall and winter. Because there’s less light—in terms of both intensity and duration—your hibernation impulse makes you want to eat more and be less energetic. Most of us cope quite well with these changes, and indeed, some become energized by the prospect of brisk January days and winter sports.
However, a significant number of people are extremely sensitive to changes in the length of the day, so much so that for them living a normal life in the modern
age is difficult. In winter, their biological clocks tell them to hibernate, even though life tells them they have work to do, meetings to attend, prime-time television shows to watch, and kids to feed. Most of these people find it difficult to fulfill the everyday demands of life during the winter months.
This syndrome has been known for millennia. Hippocrates identified it in the time of the ancient Greeks. On May 16, 1898, Arctic voyager Dr. Frederick Cook wrote poignantly of psychological changes his fellow explorers were experiencing in response to the lack of sunlight:
The winter and the darkness have slowly but steadily settled over us. . . . It is not difficult to read on the faces of my companions their thoughts and moody dispositions. . . . The curtain of blackness which has fallen over the outer world of icy desolation has also descended upon the inner world of our souls. Around the tables . . . men are sitting about sad and dejected, lost in dreams of melancholy from which, now and then, one arouses with an empty attempt at enthusiasm. For brief moments some try to break the spell by jokes, told perhaps for the fiftieth time. Others grind out a cheerful philosophy, but all efforts to infuse bright hopes fail.
This condition was formally identified in 1984 by Dr. Norman Rosenthal of the National Institute of Mental Health and was given the name seasonal affective disorder, or SAD (a highly appropriate acronym). Rosenthal established that this was a bona fide disorder by taking a group of people who reported serious symptoms of “winter depression” and tracking them through the various seasons. With startling accuracy, he showed that their symptoms worsened with the shortening days and improved as the days got longer. Since Rosenthal’s landmark study, many other researchers have confirmed his findings.
How Do You Know If You Have SAD?
The characteristic symptom of SAD is the onset of major depressive feelings at certain times of the year. Physical activity decreases. You feel very lethargic and even sluggish. Almost any physical activity seems to be too much effort. On the other hand, your appetite increases and you have a particular craving for carbohydrates and sugars, such as starches, pastries, and other sweets, and alcohol. This explains why people with SAD usually put on weight during the winter. Most people with SAD sleep for long hours—or wish they could! They
may lose interest in sex, become irritable and bad tempered, and have trouble thinking clearly and quickly, which may lead to mistakes.