Light Questions
What is ‘junk light’ and why does it matter?
"Junk light" is TrueDark’s term for the portion of the blue light spectrum (380–500nm) emitted by LED screens, fluorescent lighting, and most modern artificial light sources that is particularly disruptive to your body’s biological processes. Exposur
How does junk light impact your health?
Junk light impacts the photoreceptor cells in your eyes, disrupting communication between your eyes and your brain. This is especially harmful at night, as exposure can suppress melatonin, the hormone that helps you fall and stay asleep. Beyond sleep
Is all blue light bad for you?
Not at all. Natural blue light from the sun plays an essential role in regulating your circadian rhythm. During the day, it signals to your brain that it’s time to wake up, stay alert, and feel energized. As daylight fades, your body naturally increa
What is a circadian rhythm, and why does it matter?
Your circadian rhythm, often called your sleep/wake cycle, is your body’s internal 24-hour clock. It helps regulate when you feel awake and alert, when you get sleepy, and how your body carries out essential daily functions. This rhythm is guided by
Why is staying aligned with natural light important for your circadian rhythm?
When your body’s master clock stays aligned with the natural rise and fall of the sun, meaning you’re alert during daylight hours and asleep at night, it can send clear, well timed signals throughout your body. This alignment helps regulate essential
Where can I find more information and studies about blue light and its harmful effects?
We’d love for you to explore the TrueDark blog, where you’ll find helpful articles, research insights, and expert tips designed to make the science clear and approachable. If you’d like to go deeper, we also offer a curated collection of scientific s
How does blue light affect melatonin and sleep?
Blue light in the 460–480nm range activates specialized retinal cells (intrinsically photosensitive retinal ganglion cells, or ipRGCs) that signal the brain’s master clock (the suprachiasmatic nucleus, or SCN) to suppress melatonin production. When t