You know the drill, you snuggle in with an iPad and Netflix and hope to find some nice sleep. If you have an injury, that’s great, because some of the best healing you’ll get is while sleeping. However, what if the type of light that’s shining in your face keeps you away from the restful and restorative sleep you need?
Sleep and the Body Clock
We all want better sleep as a high-quality, full-night sleep is imperative not only to help keep the body physically productive and maintained, but it also clears the clutter from our brain and keeps our brain cells healthy. The body has its own internal “clock,” called the circadian rhythm (plants and animals also have a circadian rhythm). We function on a continuous 24-hour day-night cycle, and while many of us may consider ourselves either morning or night people, the body is naturally attuned (the terminology for this is endogenous, meaning it’s naturally built into the human makeup) to rise with the sun and sleep at dark, much like a morning glory opens its bloom with the sun each morning and closes at nightfall. While it’s been shown that humans do best when they function within their circadian rhythm, artificial light sources can disrupt our body clock by slowing the release of melatonin, our sleep hormone. These light sources are detected via our photosensitive retinal ganglion cells.
Retinal ganglion cells are neurons, or nerve cells, that live inside the retinas in our eyes. They have long projections called axons that make up the optic nerves and other optic structures that transmit visual sensation to the brain. There are specific retinal ganglion cells that are photosensitive, meaning sensitive to light, and these cells transmit information from the eyes along the retinohypothalamic tract to the hypothalamus, the part of the brain that manages the circadian rhythm. These cells detect when darkness sets in at night and mediate the secretion of melatonin. You may have heard of melatonin, as it’s a natural sleep hormone also sold over the counter as a sleep aid.
It was these photosensitive retinal ganglion cells and their response to short wavelengths (blue light) in artificial light at night that the researchers focused on.
How to Get Better Sleep? Blue-Light Blocking from the Retinal Ganglion Cells Study
In the new study 21 subjects, over a period of two weeks, were monitored for the response in their photosensitive retinal ganglion cells to both short- and long-wavelength artificial light while wearing blue-blocking glasses in the evening. Different colors of light have different wavelengths (blue and violet, for example, are higher-energy lights at the shorter end of the spectrum, while red and orange are lower energy and are at the longer end). The blue-blocking glasses only blocked the high-energy blue-colored lights at the shorter end of the wavelength spectrum from the photosensitive cells. A number of indicators were measured throughout the study period, including light exposure, retinal dilation, activity levels, sleep quality, and melatonin content.
The result? Wearing the blue-blocking glasses prior to bedtime increased melatonin secretion by 58% while the amount of sleep increased by 24 minutes. Subjects also reported better sleep in terms of the quality of their sleep. Researchers concluded that limiting or blocking artificial blue light at night may regulate sleep.
Sources of Blue Light and How to Block It
Blue light is present in all light sources. The sun is a natural source during the day, but at night, blue light exists artificially in our televisions, smartphones, computer screens, tablets, and any other electronic device with a lit screen. Just turning down the brightness level on your monitor won’t block blue light. However, you can minimize or block blue light using blue-blocker glasses, screen filters, or blue-light-blocking apps, all of which can be found online.
The upshot? If you have trouble sleeping, a simple solution to block blue light is to check the settings of your tablet. The iPad has a “Night Shift” feature found in settings under “Display” that will automatically eliminate it. Windows 10 and Mac also has a blue light filter settings. Since I both stare at a computer and an iPad before hitting the hay, you can bet that I’ll be making these changes. Who couldn’t use an extra 24 minutes of sleep a night!
Links to get rid of the blue light in your devices: