Human beings are built to respond to the natural light and dark cycle of the day. It makes sense that we would have evolved this way. After all, unlike cats, our eyes aren’t equipped to see very well in the dark. So, we had to do our hunting in the daytime and, the earlier we started looking for food, the more food we’d find before the day was over. As a consequence, our brains are more alert during daytime hours. As the sun sets, we start to slow down. Even if you consider yourself a night person, your productivity still wanes with the loss of daylight. Of course, nowadays we are surrounded by artificial light. It makes sense that this light might wreak some havoc on our sleep/wake patterns.
Circadian rhythms are our built-in 24-hour biological cycles—processes that control when our bodies engage in certain regulatory biological activities. These rhythms are independent of light. They occur even in complete 24-hour darkness, but that doesn’t mean they are impervious to disruption. The light/dark cycle regulates circadian rhythms, keeping them carefully tuned. In excessive light or darkness, the cycle can lose its synchronicity, causing all sorts of sleep-related problems. For example, melatonin, a sleep chemical we will discuss in greater detail in a moment, peaks in the evening, plateaus during the night, and drops off in the morning. Cortisol, a stress hormone, peaks in the morning and tapers off during the day. If these chemicals begin to rise and fall out of order (or in overlapping order) you may experience insomnia or excessive sleepiness. Any kind of artificial light at bedtime can affect these chemicals.
Turn Off Your Computer and Cell Phone Well Before Bedtime
Unfortunately, a series of new studies have shown that exposure to the light from self-luminous displays like computer screens, tablets, televisions, and cell phones, can dramatically reduce sleep quantity and quality. This is because the light these devices emit mimics sunlight closely enough to suppress melatonin. If your brain thinks it’s daytime, you’re less likely to feel tired and less likely to sleep deeply.
Melatonin’s Other Effects
In addition to regulating your sleep/wake cycle, melatonin can also lower blood pressure, regulate mood, and regulate glucose metabolism. It follows then, that an irregular melatonin release schedule can lead to high blood pressure, diabetes, obesity, depression, mood disorders, and heart disease. I’ll tell you, after learning all of this, turning off the lights at night never seemed more important. And, as always, if turning off the lights isn’t enough, you can reliably improve the quality of your sleep with a natural latex mattress.