If you use your computer and mobile phone frequently and especially so hours before bed, here’s why and how you can reduce blue light to your eyes and brain to improve your sleep. Light is the most powerful stimulation for shifting the phase or resetting the time of the 24 hour biological clock (or circadian rhythm). In other words, if your biological rhythm is messed up, your sleep quality will be affected.
We know that melatonin helps us sleep and is produced by the pineal gland in the brain. Our body is supposed to produce it at low levels during the day. In normal circumstances, it begins to be released a few hours before bedtime, and peaks in the middle of the night. Studies have shown that light suppresses melatonin, such that light in the early evening causes a circadian delay (resets the clock to a later schedule), and light in the early morning causes a circadian advancement (resets the clock to an earlier schedule). Viewing your devices near bedtime may result in difficulty falling asleep before midnight for example.
You see, light is made up of electromagnetic particles that travel in waves. These waves emit energy and range in length and strength. Blue light has a very short wavelength, and so produces a higher amount of energy than the other colors in the visible spectrum. Blue light is commonly emitted from screens (flat screen televisions, computers, laptops, smart phones, and tablets), electronic devices such as e-readers, and fluorescent and LED lighting.
In today’s age, after using a computer throughout the day, is it common for people to come home from work or school and relax by watching television, surfing the internet, use their mobile phones or reading an e-book. In fact, if you work mostly on the computer and use the cell phone, I will not be wrong to suggest that most of us would clock about 6-7 hours of electronic screen time.
Here’s why I caution our patients against using light-emitting devices before bed. Why? The light from our devices is “short-wavelength-enriched” meaning it has a higher concentration of blue light than natural light. While light of any kind can suppress the secretion of melatonin, blue light affects melatonin levels more than any other wavelength.
Harvard researchers and their colleagues conducted an experiment comparing the effects of 6.5 hours of exposure to blue light to exposure to green light of comparable brightness. The blue light suppressed melatonin for about twice as long as the green light and shifted circadian rhythms by twice as much (3 hours vs. 1.5 hours). For patients who report insomnia and/or fatigue as a significant symptom, we can help them test their melatonin levels via a saliva sample collected by the patient in a small vial a few times a day. This can help us better determine the best treatment for poor sleep.
How can we reduce our blue-light exposure before bed? For those who just cannot turn off digital devices, here are a few tips.
- Dim the brightness of devices. Some phones lowest light setting is still too high.
- Use apps such as Twilight on Android phones that reduce short-wavelength light in the evening.
- You can use Night-Shift mode on the iphone/ipad above iOS 9.3. Go to Settings ->Display & Brightness -> Night Shift. See pictures below. I set mine to “very warm” for the baby.
- Use dim red lights for your bed time night lights, as red light has the least power to shift circadian rhythm and suppress melatonin.
- I wear blue-light blocking eye-glasses, so don’t have to purchase blue screen filter on my computer and mobile devices. Get an extra pair of glasses
- Best, and least popular solution, is to simply turn off these devices at least 2-3 hours before going to bed.