One of the more deeply ingrained truths about sleeping is that everyone needs it to be dark to get the best sleep. Open any webpage giving advice on sleeping conditions and there will be instructions to hang heavy curtains. This not only keeps out the light, but also helps to reduce noise from outside and maintain a more even room temperature. Yet, as anyone who naps during the day or, because of shift-work, needs to sleep, having complete darkness is not necessary. People can and do sleep when they are tired, regardless of the surrounding conditions. We learn to ignore the traffic roaring past our windows, and the airplanes taking off and landing, waking only when we hear the alarm clock. Curiously, the latest piece of research was triggered by interest in people who fall asleep in front of TV sets. They have both flashing lights and sound to wake them, but sleep through. More interestingly, they can be harder to wake in the morning. This is not simply because their sleep has been disrupted by the light and sound. That happens to millions of people without the same result. It has to do with the color of the light they have been exposed to.
We are all used to thinking of most “light” in the visible spectrum as being “white”. In fact, ordinary light is a mixture of different colors from across the spectrum. There are real differences in the quality of the light projected by TV sets, the computer screens we watch so intently, lamps filtered through different shades, and so on. The eye is made up of multiple photoreceptors of different shapes and with different levels of sensitivity to colors. The most “influential” colors for sleep are blue and green, i.e. they can be used to reset the body’s circadian rhythms and establish new sleeping patterns. This can have a real benefit for those suffering from seasonal affective disorder, and help those with changing shifts adjust to different sleeping times.
It’s estimated some forty million people in the US have serious, long-term problems with sleep. The latest research with a joint team from the US and Singapore kept people awake for fifty hours with no windows or other ways of measuring the passage of time. They were than allowed to sleep for eight hours. On waking, one half of the group were exposed to green light for six hours, the other to blue. The findings are that bright blue light and dim green light help to reset the body clock and adjust hormone levels to produce “healthy” sleep at new times.
This does not deny the importance of a drug like ambien. Taken over the short term, this medication can help someone get a reasonable amount of sleep during the time available. But, if the use of colored light can naturally persuade the body to change its internal clock so that you feel tired at different times, this will be a better, long-term method of encouraging people to adjust to new time zones and to new sleeping conditions. Although the research is still in its early stages, it’s worth watching out for new information on light treatment and avoiding all problems that may come from the long-term use of ambien.
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