Blue in the Face: The Effects of Blue Light on Sleep

Matt Gratton, University of Kansas/Children's Mercy Hospital

Aside from temperature, light is the single most important trigger our body uses to regulate sleep and waking. When light is low, our bodies release a hormone called melatonin. This hormone tells the body that it’s time for sleep. 

While the sun is the major source of bright light in our lives, it’s not the only source. Electronic screens, which emit blue light, are another constant source. Exposure to blue light at bedtime can trick our bodies into slowing the release of melatonin. 

This light source is also paired with stimulating on-screen activities. Scrolling through social media, finishing up work tasks, and watching gripping TV shows are all too entertaining for our brains to put down. Blue light and internet browsing before bed can negatively affect sleep. It can disturb the body’s normal rhythms, hinder sleep, and impact overall health. 

How using screens before bed effects sleep

Exposure to blue light at night can disrupt your circadian rhythm. The circadian rhythm is a natural process that is part of the body’s internal clock. It is the cycle of physical, mental, and behavior changes that the body goes through every 24 hours. This process repeats each day, creating a healthy loop when it isn’t disturbed.

Excessive exposure to blue light before bedtime can stop smooth transitions from one point in the cycle to the next. You may find yourself feeling unrested after a nights’ sleep or waking frequently throughout the night.

When melatonin production decreases, the body may think that it’s still daytime while you’re trying to sleep. This can cause you to feel more awake. You may find yourself wanting to look at something on your phone screen until you feel tired. This has the opposite effect and only disrupts sleep further.

Preventing the negative effects of blue light on sleep

• Lights down at sundown. Turn off all bright lights at least an hour before bed. Dim light doesn’t impede the production of melatonin. 
• Stop scrolling. If possible, avoid using 30 minutes screens before bed. Even phone screens emit enough blue light to affect melatonin production. Try turning down your screen brightness or use a dim light to read a book or a printout instead of scrolling on your phone. 
• Wind down. Create a 30–60-minute wind down routine before bed, if possible. During your wind down, it’s best to perform relaxing activities such as nighttime hygiene, reading, or stretching. Try to do these outside the bedroom so your brain associates your bed with sleep only. 
• Block out distractions. Keep your sleep area clear of excess noise and light. Blackout curtains, sleep masks, or white noise generators can be effective tools.
• Waketime. Choose a consistent wake time and stick to it. Wake with enough time to have a full day and be ready for bedtime. This helps solidify your circadian rhythm and creates other sleep triggers for your body.  
• Nightlights. Sleeping with bright lights on can also disrupt natural sleep cycles. Instead, try using a dim nightlight or red light. These can help keep you drowsy and ready for sleep. 
• Get bright light during the day. Expose yourself to bright lights early and often during the day. Spend time outdoors whenever possible. This promotes wakefulness during the day and drowsiness at night. 

Blue light exposure near bedtime can have a disruptive effect on sleep. This can lead to poor sleep and drowsiness during the day. Following these steps and avoiding screens before bed can help you create better sleep habits. Improving sleep can help your mood, your health, and your ability to think clearly.  

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