Library.

“Screen time before bed has a negative effect on sleep quality.”

Multiple large-scale studies and meta-analyses consistently link pre-bed screen use with poorer sleep quality, shorter sleep duration, and delayed sleep onset in adults. A plausible biological mechanism (blue-light-mediated melatonin suppression) supports this association. However, the claim's blanket causal framing overstates the evidence: most supporting studies are observational and cannot prove causation, effects vary by age group (youth studies show weaker or null effects), and factors like content type and in-bed versus pre-bed use matter significantly.

“Blue light emitted from smartphones causes permanent retinal damage.”

This claim is false. While high-intensity blue light can damage retinal cells in laboratory settings, the American Academy of Ophthalmology, Harvard Health, and a 2023 NIH review all state there is no evidence that blue light from smartphones causes permanent retinal damage under normal use. Studies cited in support either used unrealistic exposure intensities, animal models, or showed only statistical associations — not causation. The primary proven harms of prolonged screen use are digital eye strain and sleep disruption, not permanent retinal damage.