DEAR DOCTORS: We live in Northern California and every time we have strong winds the electricity company turns off the electricity because of the risk of fire. We use candles and lanterns to light the house and my husband thinks he sleeps better these nights. Do you think there is a connection?
DEAR READER: We humans, like most living beings on this planet, are adjusted to the daily light-dark cycle. Not only is it reflected in our habits and behaviors, but research shows it has an impact at the cellular – and even molecular – level. Known as the circadian cycle and often referred to as the body clock, it controls metabolic and biological processes in our body. A number of these, including body temperature regulation, hormone secretion, and alertness, play key roles in preparing the body for the transition from wakefulness to sleep.
Studies have shown that exposure to even small amounts of artificial light can delay the body’s vital preparation for sleep. That means that with the very first campfire people lit to postpone the night, it was disrupting the delicate mechanisms of the circadian cycle. As the firelight gave way to candlelight, then gas light, and now electric light, the disturbance became more and more evident. That’s because, as we now know, spending time in bright light slows down the production of melatonin, the hormone whose night-time spikes make us sleepy. The advent of blue light in all of the screens we use has also been shown to have devastating effects on the quantity and quality of sleep.
People also read …
In a small study conducted by researchers from the University of Colorado at Boulder, eight participants camped in a wilderness area so remote that it was free from artificial light. The campers left all portable light sources behind and lived only on natural daylight. Laboratory tests showed that her daily melatonin rhythm and her individual sleep rhythm synchronized with the daily ups and downs of the light after just one week. The realization was that the circadian physiology of humans has changed due to the reduced solar radiation in our mostly indoor life and the almost constant presence of electric light.
Interestingly, another study found a wide range of tolerances for artificial light. For some participants, the dim glow of a few candles caused the same decrease and delay in melatonin production that others in the study only experienced with sustained bright light. All of this contributes to the fact that it is entirely possible that your husband’s sleep will improve with his days and evenings free of screens and electric lights. This is important as insufficient sleep and poor quality sleep are linked to a number of serious health conditions. These include high blood pressure, depression, obesity, and coronary artery disease. The sleep deficit in the United States is so severe that the Centers for Disease Control and Prevention has classified it as a public health problem.
You don’t have to get cold with electric lights. But the research is clear: spending more time in daylight and dimming the lights – and screens – after dark can help you sleep better.
Eve Glazier, MD, MBA, is an internist and associate professor of medicine at UCLA Health. Elizabeth Ko, MD, is an internist and assistant professor of medicine at UCLA Health.