Light therapy is the use of natural or artificial light to treat various ailments, but unproven uses of light extend to lasers, colors, and monochromatic lights.
The use of natural or artificial light includes colored light and high-intensity light for health purposes. It has been documented to be useful for seasonal affective disorder, with less evidence for its usefulness in the treatment of more general forms of depression and sleep disorders. Hormonal changes have been detected after treatment. Although low-level laser therapy is claimed to be useful for relieving pain, reducing inflammation, and helping to heal wounds, strong scientific proof of these effects is still needed.
The use of light as a therapeutic tool has a long history, with reports of sunlight being used to treat depression and lethargy over 2000 years ago in ancient Greece and Rome. The use of light in therapy today however stems largely from research carried out in the 1980s that looked at the cycle of depression, and other problems, associated with changes in the seasons of the year.
Many of the body's functions are regulated by an internal clock, which operates on a pattern that repeats roughly every 24 hours and that gives a rhythm to our lives. Indeed, this is often referred to as the body's circadian rhythm, from the Latin 'circa dies' meaning 'about a day'.
Unlike your kitchen clock or wristwatch, however, which are more often than not powered by batteries these days, your body clock is essentially a chemical clock and is powered by a variety of different environmental factors, the most significant of which is the alternating pattern between daylight to darkness. In simple terms, as your body senses the fall of darkness it sends out signals, shutting down many of your body's functions in preparation for sleep. Similarly, as daylight returns, signals are again sent out for these same functions to start up again.
There are three main types of insomnia - initial, or sleep onset, insomnia (difficulty falling asleep), middle insomnia (difficulty remaining asleep through the night) and late, or terminal, insomnia (waking too early in the morning). It is in the first and last of these three that light therapy can be particularly useful.
In the case of initial insomnia your body clock has often shifted so that, instead of sending out the chemical signals to start shutting down at say ten or eleven o'clock in the evening, your body doesn't start sending out the necessary messages until perhaps one or two o'clock in the morning.
Similarly, at perhaps seven o'clock in the morning, when you should be starting your day, your body clock hasn't yet started to send out its 'wake up' signals and won't be doing so for perhaps another three or four hours.
To solve this problem, and to re-adjust your body clock, bright light therapy can be used in the morning to get you up and going. If bright light therapy is used for perhaps thirty minutes to an hour each morning for several days, your internal body clock will gradually shift to align itself with your normal sleeping routine.
The same treatment can be applied in the case of late insomnia. In this case your body clock is set too early so that it is telling you to go to bed before it is time to do so and similarly to get up too early.
Here, bright light therapy can again be used to re-adjust your body clock, but now needs to be applied in the evening, rather than in the morning. Although bright light therapy is being used increasingly to treat insomnia it remains very much a secondary form of treatment and has yet to achieve the prominence that it deserves. It is, however, gaining ground in the treatment of insomnia associated with two specific problems, those of jet lag and shift work, and so it is perhaps only a matter of time before it becomes a far more widely used form of treatment for insomnia generally.
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