Are you one of those people who can’t seem to fall asleep after late-night doomscrolling or binge-watching a show, you’re not alone. Over exposure to blue light can leave you tossing and turning when you should be sleeping. Let’s face it, blue light is everywhere and it’s not all bad. But when it comes to your sleep, eyes, and even hormones, it might be doing more harm than you think.
To put it simply, blue light is a high-energy, short wavelength light that’s naturally emitted by the sun. It’s actually a good thing during the day, it helps boost energy, mood, and alertness. The problem is the constant exposure to artificial sources of blue light from our devices, and the fact that most of us are on them from basically the moment we wake up until right before we go to bed.
So here’s the truth: blue light can penetrate deep into the eye, all the way to your macula lutea, a small yellowish area in the retina that’s responsible for sharp central vision and color perception. It’s important for tasks such as reading, driving, or recognizing faces. The macula lutea is rich in two carotenoids: Lutein and Zeaxanthin, which are antioxidants that help filter harmful blue light and protect your retina. But, prolonged exposure to blue light can cause damage to these protective compounds and eventually lead to a condition called macular degeneration, which is the leading cause of sight loss in senior citizens.
Blue light exposure, especially at night, can also suppress melatonin production; the hormone that tells your brain it’s time to sleep. Here’s a simple version of what happens:
1. Photosensitive cells in your retina called ipRGCs detect blue light.
2. The ipRGCs send a signal to the suprachiasmatic nucleus (SCN), a region in the hypothalamus that’s known as the master clock of your body.
3. The SCN interprets this signal as daytime, and sends an inhibitory signal to the pineal gland, which is responsible for producing melatonin. It tells it to reduce or stop producing melatonin.
4. Without melatonin, your body stays alert and you don’t feel sleepy. Over time, this can impact your mood, memory, immune function, and even metabolism.
It doesn’t stop at melatonin, it also affects other hormones and neurotransmitters including:
Cortisol: Blue light can increase cortisol levels. Cortisol is good for alertness, but chronic elevation can lead to fatigue and anxiety.
GABA: This neurotransmitter helps promote relaxation and winding down. Suppression of GABA activity can lead to poor sleep quality and brain fog.
Dopamine: Some research suggests that it can also cause an imbalance in dopamine levels, affecting mood, motivation, and emotional regulation.
As you can see, excessive exposure to blue light results in more than just a restless night or a headache. From eye health and sleep quality to hormone balance, the light from your phone is doing more than you realize
So, take care of your eyes, and your sleep. Your body will thank you for it.
References
Harvard Health Publishing. (2020). Blue light has a dark side. Harvard Medical School. Blue light has a dark side - Harvard Health
Bollinger, E., & Bollinger, E. (2025, May 22). Your brain on blue light: Understanding the science. BlackDoctor.org. https://blackdoctor.org/your-brain-on-blue-light-understanding-the-science/
Kanukuntla, Dr. J. (2025, July 9). How blue light affects hormones. Best Hospitals in Hyderabad. https://continentalhospitals.com/blog/how-blue-light-affects-hormones/
This was an interesting read I really liked the way you made the connection between blue light, the retina and also melatonin, it makes the physiology behind it more easier to understand. I knew that blue light affected sleep but never knew what it could do to hormone levels like increasing cortisol levels. It is crazy how something simple like checking our phones can throw off many things internally. It makes me wonder how simple changes could make a very big difference such as limiting screen time before we go to bed. Really good job on explaining the short and long term effects of blue light exposure.
ReplyDeleteI was guilty for doomscrolling and falling asleep to YouTube or TikTok videos, and waking up the next morning feeling iffy. These days, it is best to have 15-30 minutes of 'no-screen time' before going to sleep. I knew blue light interfered with melatonin but I did not know that it may affect with cortisol, GABA and dopamine. It's a lot harder to deal with since we rely on our phone, iPads, and computers on a day-to-day basis.
ReplyDeleteI know that there are blue light glasses that blocks the blue light, and a "What To Eat (and Avoid) When You Have Macular Degeneration" blog post done by Cleveland Clinic. If someone is going through macular degeneration, what would you recommend to prevent it from worsening?
We always hear about how it is bad to be on screens before bed because it makes it more and more difficult to sleep, but I never realized the depth of harm that is being done. I have fallen asleep with some kind of device on for close to 10 years, and it never occurred to me that some of my issues with sleep may have been compounded over all of that time because of the screens and blue light. I would be interested to see if there was a correlation between people who use screens for their jobs versus people who don't and their sleep habits. Does blue light "accumiliate" through the day, or does it "filter out"?
ReplyDeleteWhat an interesting blog!! All of the points you discussed seem very reasonable, and I like how you clearly explained the step in why blue light suppresses blue light. Though many of us are aware that using our phones or other technologies before bedtime is bad, as it negatively impacts our sleep, I am curious why so many people are so addicted to the idea of scrolling and continue scrolling until the point where it gets too late to get good quality sleep.
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