The days are darkening here in Corvallis, and it won't be long until what little slanty sun could shine will be thwarted by rain clouds. If you notice yourself getting sleepy, lethargic, or gloomy, you're in good company. Seasonal changes in light have a very real and physiologic effect on mood and energy. Our brains and bodies are set up by evolution to react to long light days with increased energy (work those fields! harvest!) and to cooler, dark days by slowing the system down (sleep! now sleep some more!). Our bodies would be perfectly happy going to bed not long after the sun sets. That probably worked well in days before widespread use of artificial light and 24/7 availability of food and things to do-- but it's unrealistic for most of us now. The result in the split between rapid societal evolution and much slower physiologic evolution can be sleep, energy and mood disorders.
A light box can address both typical and more drastic results of the effects of waning light on the brain and body. Light boxes produce effects similar to sun exposure and can be used in the morning to assist in wakefulness and mood regulation and in the afternoon to increase energy. Exposure is typically between 15-30 minutes at a regular time each a.m. or early afternoon. To be effective, the light source should be at or above face level, with eyes open (although it is not necessary or recommended to look directly at the light)and within 15-30 inches of the light source. Specific instructions vary according to model. There is a great deal of evidence of effectiveness in the use of light boxes to treat seasonal affective disorder, a type of depression linked to low winter light.
Because they have a real--and sometimes profound-- effect, they are best used according to specific directives based on the particular mood or sleep issues one is experiencing. In some cases, use can increase hypomania (agitation, excess energy, and insomnia among other symptoms). Usually a reduction in the exposure time is enough to remedy that. However, I encourage persons considering light therapy to consult their physician or mental health practitioner and have some sort of system in place to track results. Because it isn't completely clear that such intense light exposure is safe over long periods for eyes, light therapy isn't for everyone and the risks as well as benefits should be explored.
I'm a chronically terrible sleeper, and an even worse waker. I noticed that the best sleep I have is when I am camping and rise and go to sleep with the summer sun. Since that time frame is typically also when I rise and wake in the winter, I have found great benefit in the use of a dusk/dawn simulator. The device I use attaches to my bedside lamp and is programmed to turn the (100 watt full spectrum) light down very gradually in the evening and then up again gradually in the morning. I use it from October to May and find I don't even need an alarm clock, as the dawning light creates a gentle alertness over time. I wake up refreshed instead of startled. Research suggests that gradual lightening stimulates a chemical cue to awakening, just as gradual darkness stimulates a chemical cue to drowsiness. I rarely use a light box since I've bought my dawn simulator. They aren't cheap-- mine was $150-- but I find it a bargain for the help it's provided me with sleep and waking.
Meanwhile, if it's a nice day, get out there! I recently read that the average American is getting LESS than the 20 minutes of sun a day needed by the body to manufacture adequate vitamin D. My MD tells me northwesters are often deficient, and the government just doubled the recommended RDA.
For more information on light and mood, see the wonderful website of Dr. James Phelps at www.psycheducation.org. Dr. Phelps is a psychiatrist who has done extensive literature review on the subject of mood disorders and light therapy.
