How Does Light Affect Sleep?
Do you ever ask yourself why it is that we sleep at night and not during the day; how does light affect sleep? Well, we did too, and after putting on our researcher’s cap, here’s what we found out about it.
For humans at least, light triggers alertness, whether it be from the sun entering your bedroom in the morning, or a being in a well lit area in the evening. Darkness is essential to sleep. The absence of light sends signals to the body that it’s time to rest. Exposure to light when there shouldn’t be any can affect the body’s internal clock, the biological mechanism that regulates sleep-wake cycles, in ways that interfere with sleep quantity and quality. Melatonin, also known as the “sleep hormone”, is also inhibited when you’re exposed to light during late hours of the night. Melatonin levels naturally rise as darkness falls and peaks in the early hours of the morning.
Remember that, for most of human history, outside of fire, there was no such thing as having light during the night, so relatively speaking, this is a new problem. Thanks to the invention of the lightbulb, we are now exposed to much more light at night than we had been throughout evolution. This pattern of light exposure is almost certain to have affected sleep patterns. Generally speaking, humans now have later sleep times than before, and sleep less overall than before.
However, problems can also occur when our exposure to light changes due to a shift in time zones or an altered sleep-wake cycle due to working an untraditional work shift. Under regular conditions, our internal clock strongly influences our ability to sleep at various times over the course of a 24-hour day, as well as which sleep stages we experience when we do sleep. With time zone and work shift changes can come two things, insomnia and/or jet lag; you want neither.
Now, the affects of light can be different from person to person. What about you, can you sleep in broad daylight, or do you need a dark room to doze off? Let us know.