Changes in prefrontal hemodynamics and mood states during screen use: a functional near-infrared spectroscopy study.

Screen use has been associated with poor cognitive and mental health, yet few studies have examined its effects on brain activity. Our aims were to describe changes in brain activity and mood states following brief exposure to screen-based content; assess the feasibility of using functional near-infrared spectroscopy (fNIRS) to measure these effects; and gather preliminary data to inform future investigations. Twenty-seven young people (age = 21.5 ± 2.8 years; range = 18-25) completed six consecutive 3-min screen conditions in a psuedorandomized cross over design. All screen exposures were presented on an iPhone 12-Max while sitting. Hemodynamic changes in the dorsolateral prefrontal cortex (dlPFC) were measured continuously using fNIRS (Portalite Mk II). Changes in mood states (energy, tension, focus, happiness) were assessed before and after each condition. Condition exposure altered the hemodynamic response in the dlPFC, where oxygenated hemoglobin (HbO) increased more compared to baseline after exposure to social media (largest increase), gaming, and TV-viewing (smallest increase), respectively. Deoxygenated hemoglobin (HbR) and total hemoglobin (HbT) increased more following exposure to gaming (largest increase), social media, and TV-viewing (smallest increase), respectively. Both TV-viewing and gaming were associated with increased focus relative to baseline, whereas social media use was associated with decreased focus. Findings indicate that even short durations of screen use have measurable effects on brain regions involved in cognitive control, emotion, and social decision making. These effects are nuanced and context dependent, rather than universally beneficial or detrimental. fNIRS is a feasible method for measuring these effects.