Nighttime Smartphone Blue Light Exposure, Sleep Quality, and Metabolic Health in Adolescents

Nighttime smartphone use has become very common among adolescents in recent years, and this may affect both sleep quality and metabolic health. However, the specific effect of smartphone-emitted blue light is difficult to separate from behavioral forms of smartphone-related sleep disruption, especially when looking at adolescents. Smartphone-emitted blue light can disrupt circadian rhythms and melatonin secretion. This can potentially affect glucose regulation and insulin sensitivity, leading to specific metabolic outcomes in adolescents. However, other forms of sleep disruption (stress, room temperature, physical discomfort, and bedtime delay) can also contribute to these outcomes. This paper looks at the association between sleep quality and nighttime smartphone-emitted blue light, compared with other forms of sleep disruption, and metabolic outcomes in adolescents. This study uses a literature review and survey to analyze whether blue light has a specific role in these relationships. 70 individuals responded to the survey. Greater smartphone use after getting into bed was associated with poorer self-reported sleep quality (ρ = −0.284, p = 0.017). Difficulty stopping smartphone use before bed was also associated with more frequent bedtime delay (ρ = 0.392, p = 0.001). However, blue-light-reduction feature use was not significantly associated with sleep quality (ρ = 0.176, p = 0.144). Blue-light-specific associations were weaker in the survey, while the literature showed stronger evidence of blue light affecting sleep and metabolic regulation. This difference suggests that other behavioral, psychological, and environmental forms of sleep disruption may also contribute to these outcomes alongside blue-light exposure