Christmas vacation is ending, It has been wonderful to spend some relaxing time with family, getting up later in the day, lounging around and playing games, reading, or watching TV… and eating too much good food.
Now the challenge is getting back to a more productive schedule. For many of us, our bodies are in a “hibernating” mode that makes it hard to wake up in the morning.
Think of a bear and you will get the picture. Bears, during the winter, don’t actually sleep all the time, rather they enter a twilight zone where they alternate, almost at random, between a lethargic, half asleep, waking state, and a very light, half awake, sleeping state. 
What happens that makes this possible is that the bear’s internal clocks, their biorhythms, are all out of sync with each other, and out of sync with the outside world.
If we lived back in the past, when there weren’t the crazy demands of modern life, many of us would be naturally, and perhaps pleasantly, semi-hibernating all winter.
But we don’t.
The solution to this problem is to use a therapy light to resynchronize our body clocks. Bright light in the morning is what “sets” our clocks every morning, and the reason that we enter semi-hibernation is because there is very little bright light in the winter… especially if we work indoors and drive to work (usual indoor light is not bright enough to synchronize our body clocks).
There are two types of therapy lights: full spectrum lights and blue spectrum lights.
Blue Light
Blue spectrum lights make use of the fact that it is the blue end of the light spectrum that is mostly responsible for setting our body clocks. The result is that blue spectrum lights can be smaller and put out less total light, because 
they just emit the “active” part of the spectrum. You can, for example, buy one that runs on a battery and can therefore be taken with you on business trips or vacations. The trouble with blue spectrum lights is that they have a theoretical potential for causing eye damage, especially if you have blue eyes (which are more sensitive to light). I say theoretical because, whereas it is clear that ultraviolet light can hurt your eyes, it is not clear that blue light can do so. And if it does hurt your eyes, it is much less of a problem than going outdoors in the sun without sunglasses…
The first, and in many ways still the best device is the Philips goLite Blue. Among other things we like, is the option to use this device on the road with an internal battery.
Full Spectrum Light
Full spectrum lights serve two purposes. They sync your body clocks and they help you see things better. Full 
spectrum light is the ideal light for doing things that require good vision – reading, knitting, etcetera. I particularly like full spectrum floor lamps, because one of the most common problems with people who use therapy lights is that the light is not close enough to their eyes, often because it is on a table that is already a couple of feet below eye level. The BlueMax lights are compact and reliable and I have several of them for personal use (at home, and in two of my offices). You can see one being used as a sewing light in the picture at the right.
Read the Fine Print
We have recently run across several “therapy lights” claiming to provide 10,000 lux (the standard “dose”of light), however the fine print reveals that these lights provide that intensity of light at ridiculously small distances from the bulb (in one case, 6 inches). In practice, this means that you won’t be getting enough light. Look at the small print, you want a light that delivers 10,000 lux at 1.5 feet, and that blocks ultraviolet light.
OK, now that you have a light, what do you do with it?
Recommended Use
My usual prescription is 45 minutes of bright light (10,000 lux of full spectrum light) every morning before 9 am.
The key is that the light has to be set up so that it is no more than one and a half feet from your eyes. This may require some creative use of stands, if you haven’t bought a floor lamp. The fact that it is awkward to set up a light is illustrated by the fact that most ads for therapy lights show them being used incorrectly… 
The picture on the left shows a blue light improperly set up (it is from the Mayo Clinic website) and the picture on the right shows a full spectrum light improperly set up (it is from the Harvard website)…
When you have set up the light check to make sure that you can see it with both eyes (close one eye and look towards the light, then close the other eye and do the same). You don’t need to look at it when it is on, but it should be in your peripheral vision.
Most people do other things while they are getting light exposure. For example, right now I am writing this blog post while sitting under a therapy light. Other people watch TV or read.
That is it.
Therapy light should help you to sleep better (more deeply) and feel more alert during the day within two or three days. And if you have a tendency to seasonal depression, it should help your mood almost as quickly.
For More Information
Supercharge Your Circadian Rhythms – this is a nice summary of why light matters, and provides more details about how to avoid dysregulated circadian rhythms.
Is Daylight Savings Time Making You Crazy? – a post that talks about why the switch from daylight savings to standard time might make you more depressed.
Luminette Light Therapy Glasses – a new option for therapy light is this portable device.
Using a Therapy Light – More on how to use a light.