A person’s sleep-wake cycle is controlled by what’s called the internal circadian rhythm, which in turn is largely controlled by the presence and absence of light going through the eyes and sending signals to the brain.
With at least 50 percent of Americans reporting they generally don’t get enough sleep, it would be beneficial if we could aid our body’s internal clock, which runs in 24-hour cycles, more or less. Again, think light — daytime sunlight tells the brain that we need to be active, and nighttime and its absence of light tells the brain it’s time to sleep. If we can control our light sources, we can help send the right signals to our brain.
University of Colorado researchers recently reported that a week in the woods camping out — back to nature! — can go a long ways toward resetting our internal sleep-wake clock. Problem is, how many of us figure to spend a week camping sans light anytime soon?
Therefore, the answer must be more practical. Since we live in a 24/7 lighted world, at least potentially, it behooves us to reexamine how we treat light and light-emitting devices at home, in the crucial hours before bedtime. Even working on a computer, sending text messages on a cell phone or watching television can send signals to our brain that we’re still active and there’s no reason to produce melatonin, the sleep hormone.
It may be impractical to turn off all light sources two hours before going to bed, but we can at least limit our involvement. Many sleep researchers recommend using blue-blocking glasses at night since blue light is the trigger that tells the brain it’s daytime.
Light sources belong to what sleep scientists call zeitgeibers — literally, time givers. Exposure to light can literally reset your internal 24-hour clock, so that your daytime might start at 8 p.m., thus making it extremely difficult to get a good night’s sleep.
Consider this: When researchers invited volunteers into the laboratory and exposed them to light at intervals that were at odds with the outside world, the participants unconsciously reset their biological clocks to match the new light input.
Bottom line, then, is that it’s easy to get our internal clocks out of sync with reality. We need sunlight in the daytime for our health and as a trigger for our internal clocks, but at night we need to moderate the light we let into our lives. Whether we use blue-blocking glasses or just pay more attention to what we do at night involving light sources (which these days are fairly ubiquitous), we need to be careful not to unconsciously reset our body clocks so that we can never again enjoy a normal night’s sleep.
In short, a lot of our sleep difficulties are under our control, but we’re just not paying enough attention to what our nighttime activities mean for our sleep and health.