Blue light, particularly when exposed to directly before bedtime, can have serious implications on sleep quality, circadian phase, and cycle durations. Exposure to blue light suppresses the secretion of melatonin, a hormone that influences circadian rhythms, and even dim light can interfere with a person’s circadian rhythm and melatonin secretion .
Blue light exposure from screens is relatively small compared to the amount of exposure from the sun. However, there is concern about the long-term effects of screen exposure, especially when it comes to excessive screen time and screens being too close to the eyes. Studies have shown that exposure to blue light before bedtime can disrupt sleep patterns and affect the body’s creation of melatonin, which plays a crucial role in regulating the circadian system .
Blue light is part of the visible light spectrum and is emitted by the sun, as well as digital devices like laptops, smartphones, and LED lights. Exposure to blue light during the day can improve performance, attention, and sleep quality at night. Strategically timed exposure to blue light can help treat sleep disorders by realigning the body’s circadian rhythms .
To protect your circadian rhythm and minimize the impact of blue light on sleep, it is recommended to limit screen time in the two to three hours before bedtime. Nighttime settings on devices can also be used to minimize blue light exposure in the evenings .
While there are claims that blue light-blocking glasses can help with sleep, the studies on whether blue light affects circadian rhythms have mostly been conducted on animals rather than humans. The main factor in how screens disrupt healthy sleep is likely the content being viewed on the screen, rather than the blue light itself .