Once upon a time, human beings lived from sunrise to not long after sunset. Today, your body still sets its clock by sunlight.
Since artificial light came along, most of us stay up well past sunset. Shift work, personal habits, and individual genes can push your clock’s timing mechanism even later. Night owls have a rough time in the typical office setting — bosses tend to admire employees who show up at 8 a.m. and frown upon those who slip in just before 10 a.m., even if they put in the same number of hours. But dragging yourself to work after too little sleep is also a bad idea. Chronic sleep deprivation has been tied to a range of dangers, including heart disease, obesity, and depression. Fortunately, there are ways to shift your body clock into keeping time earlier.
Morning sunshine is your friend. Ideally, sleep in a room with morning sunlight, and keep your blinds up. If that can’t be arranged, sleep therapy using a "light box" can wake you up with full-spectrum light. Nancy Collop, MD, director of the Emory Sleep Center in Atlanta, recommends a light box that produces an hour of 2,500 lux, a photometric unit of illuminance, of natural-spectrum light each morning. Even a half hour will help. At the end of the day, cut out screen time with laptops and cell-phones as early as possible.
Over an 8-hour day, we need exposure to at least 2,500 lux over 2 hours to sleep well at night, research suggests. Standard office lighting provides about 500 lux — compared to about 11,000 outdoors in full daylight on a clear day, roughly a half-hour of bright sunlight. Dimly-lit hospital rooms, on the other hand, interfere with sleep and are linked to fatigue, aggravating pain.
As the weather warms this spring, consider bathing yourself in sunlight and entirely removing artificial light from your life. In one study, only a week of camping in the Rockies — without flashlights or cell phones — was enough to synchronize the circadian clocks of eight people to the solar day, regardless of whether they were early birds or night owls at home.
Their normal habits had been determined previously, during a week when they wore wrist monitors, recording the timing and intensity their light exposure and keeping track of their activity, including sleep. The researchers also measured their levels of the sleep-regulating hormone melatonin, which rises before sleep and declines as we awaken.
After the week of natural light only (including the glow of a campfire), their bodies released melatonin near sunset, and levels declined around sunrise.
In a related study, researchers tested the effect of taking .5 mg of melatonin about 6 hours before your normal bedtime, exposure to 3 hours of 3,000 lux broad spectrum white light beginning an hour before normal rising time — and the two combined. It turned out that the melatonin and white light worked about equally well to move the body clock earlier, and the combination did the best job. This approach could be useful to minimize jet lag after traveling east or to shift your clock earlier when you start a new work or school schedule.
Being slow in the morning doesn’t mean you’re lazy or apathetic. Don’t assume, however, that you have a strong genetic tendency toward dragging in the morning — you may simply have fallen into night-owl habits. After about the age of 60, even night owls shift to earlier body-clock schedules.
March 20, 2015
Christopher Nystuen, MD, MBA