For years, 'night mode' features on devices from Apple, Microsoft, and others have promised to cut blue light exposure and protect sleep. Yet, a rigorous U.S. study finds it offers little real benefit.
Blue light from screens is well-known to strain eyes and disrupt sleep by suppressing melatonin, the hormone that regulates rest. It's even linked to age-related macular degeneration (AMD), a retinal condition common in those over 50. Apple's 2016 iOS Night Shift was a pioneer, shifting screen colors to reduce short-wavelength blue light. Soon after, Microsoft followed with similar tools in Windows 10.
But research from Brigham Young University in Provo, Utah, published in Sleep Health on April 16, 2021, challenges this. Lead researcher Chad Jensen and team from Cincinnati Children's Hospital Medical Center tested 167 young adults aged 18-24, split into three groups: night mode users, regular screen users before bed, and a no-screen group.
Surprisingly, sleep quality showed no significant differences across groups. Even narrowing to two groups based on prior sleep logs, improvements were minimal—sleep duration hovered around 7 hours in better-sleepers versus under 6 hours otherwise. Any small gains from night mode were negligible.
The no-screen group consistently reported superior sleep quality and longer duration. Experts conclude that screen time itself—not just blue light—is the primary disruptor, as engaging activities keep the brain alert.
