Rethinking Screen Time: Why Blue Light Might Not Be the Sleep Culprit

For years, experts have warned that exposure to blue light from devices such as smartphones, televisions, and laptops before bedtime can interfere with sleep. This light suppresses melatonin production, the hormone that signals the body to prepare for rest, leading to increased alertness and difficulty falling and staying asleep.

However, the connection between blue light and sleep disruption is more nuanced than previously believed. Recent analyses indicate that blue light alone may not be the primary factor causing poor sleep quality. In some cases, screen use might even have a neutral or positive effect on sleep.

This article explores what current research truly reveals about blue light and offers insights on how to improve sleep amidst today's digital environment.

Many studies on blue light and sleep are dated and limited by small sample sizes. Additionally, much of the research was conducted in highly controlled laboratory settings, which may not fully represent everyday life conditions.

While blue light exposure can reduce melatonin levels, evidence suggests that screen use does not always lead to this effect. Factors such as the duration of device use, the distance from the eyes, and screen brightness appear to influence the degree of melatonin suppression.

For example, research has shown that using an iPad at full brightness for two hours results in a slight melatonin decrease, whereas one hour of use produces no significant change. Watching television from about eight feet away has been found to have no impact on melatonin levels. Moreover, higher screen brightness settings can suppress melatonin more than dimmer settings.

Daytime habits also play a role. Exposure to ample natural sunlight during the day may reduce the sensitivity to melatonin suppression caused by evening screen exposure.

Individual sensitivity to blue light varies widely. In one study, some participants required up to 40 times more light exposure to achieve the same melatonin suppression effect as the most sensitive individuals.

It remains uncertain whether the melatonin suppression from screen exposure is sufficient to negatively affect sleep quality. Other factors such as caffeine intake, stress, or environmental noises might also contribute to sleep disturbances, complicating cause-and-effect conclusions.

Reviews of multiple studies reveal mixed findings. While many research efforts found no clear link between blue light exposure and poor sleep, a few reported some associations.

Recent assessments conclude that current evidence is insufficient to definitively state that screen exposure to blue light before bedtime harms sleep.

More research is needed to clarify these relationships and better understand the factors influencing sleep in the digital age.

Beyond light exposure, what users do on their devices may significantly affect sleep. Interactive activities like gaming, social media browsing, online shopping, and gambling can activate the brain's reward system, keeping users engaged and awake later into the night.

Social media platforms are particularly designed to capture and hold attention, which can prolong screen time and hinder sleep onset.

Both stimulating and distressing digital content—ranging from chatting with friends and playing games to endlessly scrolling through upsetting news or videos—can heighten brain activity in ways that disrupt sleep.

Though you can turn off your device, the mind may remain active and alert, making it difficult to fall asleep.

A 2024 study involving around 500 adolescents found that those who engaged in texting, talking, or gaming on devices before bedtime tended to fall asleep later and sleep fewer hours than peers who did not.

There is less consensus on how other screen activities like watching television or reading affect sleep, which may depend on the type of content consumed.

Starting a new suspenseful show or book is more likely to interfere with sleep than revisiting familiar, comforting series or stories. Knowing the ending can make it easier to disengage and fall asleep.

The adolescent study also found no significant differences in sleep for those who watched TV or movies before bed versus those who did not, though content types were not specified.

For individuals struggling with negative thoughts at bedtime, watching certain calming shows or movies, or reading relaxing material on a tablet, may help distract from intrusive thoughts and facilitate sleep.

The ideal content tends to be positive and familiar, such as a light-hearted comedy. One insomnia patient found relief by watching a sitcom repeatedly, effectively curbing rumination.

Regardless of content, experts advise avoiding screen use in bed to help the brain associate the sleeping environment exclusively with rest.

Ultimately, some individuals might find that screen use does not negatively impact their sleep. For those people, there is no compelling reason to change their habits.

If you fall asleep quickly, sleep soundly through the night, and feel refreshed in the morning, your current routine may be working well without adjustments.