Blue Light and Sleep: What You Need to Know

We’ve all been there—scrolling through our phones in bed, telling ourselves “just five more minutes,” only to find ourselves wide awake an hour later. While we might blame our lack of willpower, there’s actually some interesting science behind why that glowing screen makes it so hard to fall asleep, often leading to poor sleep quality, sleep disruption, and even sleep deprivation.

What’s the Deal with Blue Light?

Blue light is a type of short wavelength light within the visible light spectrum that produces higher amounts of energy. It is emitted by both natural and artificial light sources, including the sun, light emitting diodes (LEDs), and fluorescent lights. The blue spectrum is especially prominent in LED and fluorescent lighting, which are common in modern homes and devices. During the day, blue light is actually beneficial—it boosts attention, reaction times, cognitive performance, and mood, and helps regulate the circadian system. The sun is our primary source of blue light, which is why natural light helps us feel alert and awake.

Blue light can be compared to other colors in the visible spectrum, such as red light, green light, and orange light. Red light and amber light have longer wavelengths and are less likely to disrupt sleep, while green light has a lesser effect on melatonin suppression and circadian phase shifts compared to blue light. White light contains all colors of the visible spectrum, including blue wavelengths, and is commonly produced by artificial light sources like LED bulbs and fluorescent lights.

The problem is that our electronic devices (smartphones, tablets, computers, LED TVs) also emit significant amounts of blue light. The blue light emitted from these blue light emitting devices is a major source of artificial blue light in the evening. When we use these devices at night, we’re essentially telling our brains that it’s still daytime, increasing blue light exposure and potentially causing negative effects on sleep health.

How Blue Light Disrupts Your Sleep

Your body has an internal clock called the circadian rhythm, or human rhythm, which regulates your sleep-wake cycle and sleep cycles. This rhythm is heavily influenced by light exposure, especially blue wavelengths. When it gets dark, your brain produces melatonin, a hormone that makes you feel sleepy. When it’s light, melatonin production decreases, helping you stay awake and alert.

Blue light is particularly effective at suppressing melatonin production and melatonin secretion. Blue light exposure can trick the brain into thinking it is still daytime, disrupting circadian rhythms and leaving individuals feeling alert instead of tired. Studies have shown that exposure to blue light in the evening can delay melatonin onset by over 50% and suppress melatonin levels more powerfully than other light colors. Blue light exposure at night can shift your internal biological clock by up to 3 hours, leading to circadian misalignment and sleep disturbances. Even dim light at night, including from artificial sources, can suppress melatonin secretion and disrupt sleep cycles.

Chronic exposure to blue light at night can lead to negative health impacts, including metabolic disorders and mental health issues such as depression. Light exposure at night, including blue light, is associated with an increased risk for depression, diabetes, and cardiovascular problems. This can create a frustrating cycle where you stay up later, get less sleep, and feel groggy the next day, experiencing bad sleep, poor sleep quality, and daytime dysfunction. For athletes and those with busy training schedules, managing blue light exposure is crucial for good sleep hygiene, sleep efficacy, and optimal physical performance.

What You Can Do About It

The good news is that you don’t need to swear off technology entirely. Here are some practical strategies to minimize blue light’s impact on your sleep quality, sleep efficiency, and overall sleep health:

The most effective way to reduce blue light exposure in the evening is to simply turn off the sources, such as electronic devices and bright lights. Dimming or reducing LED and fluorescent lighting in your home can help decrease blue light exposure and support restful and good sleep.

Create a digital curfew. Try to stop using electronic devices at least one to two hours before bed. Use that time for other relaxing activities like reading a physical book, taking a bath, or practicing gentle stretches.

Use night mode features. Most smartphones and computers now have built-in settings that reduce blue light emission in the evening. On iPhones, this is called Night Shift; on Android devices, it’s often called Night Mode or Blue Light Filter. These features shift your screen’s colors toward the warmer, amber end of the spectrum, reducing artificial blue light and supporting better sleep latency.

Try blue light blocking glasses. If you must use devices in the evening, consider wearing blue blocking glasses specifically designed to block blue light. Wearing blue light blocking glasses can reduce the melatonin-suppressing effects of bright light, and using them for two hours before sleeping can improve sleep duration and overall quality of life. Blue light blocking glasses can also help improve sleep efficiency and sleep latency in various sleep disorder conditions, and are recommended for those experiencing sleep disturbances or sleep disorders. Blocking nocturnal blue light, such as by using blue blocking glasses or avoiding blue light emitting devices, can improve sleep health and reduce sleep disturbances.

Adjust your lighting. Dim the lights in your home as evening approaches. Consider using warm-colored bulbs in your bedroom and avoiding bright overhead lights before bed. Bright white LED bulbs can disrupt circadian rhythms, while red or amber light has the least impact on sleep. Some people find that red or amber night lights work well if they need some illumination.

Prioritize morning light exposure. Getting bright light exposure early in the day helps reinforce your circadian rhythm, making it easier for your body to recognize when it’s time to wind down at night. Blue light is beneficial during the day, helping to improve sleep quality and daytime activity. Try to spend some time outdoors in natural sunlight each morning, or at least near a bright window.

Keep your bedroom dark. Make sure your sleeping environment is as dark as possible. Use blackout curtains, cover or remove electronic devices with glowing lights, and avoid checking your phone if you wake up during the night.

Finding What Works for You

Everyone’s sensitivity to blue light is different. Young adults may be particularly sensitive to blue light exposure, and those with sleep disorders or mental health concerns should be especially mindful. Some people can scroll through their phones right up until bedtime without issue, while others find that even a quick email check disrupts their sleep. Pay attention to your own patterns and adjust accordingly.

The key is being mindful about your evening technology use and creating habits that support good sleep hygiene and higher sleep efficacy. Small changes, like charging your phone outside the bedroom or reading a physical book before bed instead of a tablet, can make a meaningful difference in how well you sleep and how rested you feel the next day. Strategically timed exposure to blue light can also help treat several sleep disorders by realigning circadian rhythms.

Your sleep is worth protecting—and sometimes that means putting down the screen and giving your brain the darkness it needs to prepare for rest. Further research, including randomized controlled trials and systematic reviews, is needed to fully understand the effects of blue light on sleep health, cognitive performance, and physical performance, but managing blue light exposure remains one of the very important factors for achieving good sleep quality and optimal wellbeing.