Background: Widespread smartphone use during the pre-sleep period has raised concerns regarding its potential effects on sleep physiology and cardiovascular regulation. Exposure to screen light and cognitive stimulation before bedtime may alter autonomic balance, leading to measurable changes in morning cardiovascular parameters. This study aimed to evaluate the effect of smartphone screen exposure before sleep on morning heart rate and blood pressure in healthy young adults. Material and methods: A prospective observational study was conducted among 80 healthy adults aged 18–35 years. Participants were grouped based on smartphone screen exposure during the 60 minutes preceding sleep into a high-exposure group (≥30 minutes) and a low-exposure group (<10 minutes). Pre-sleep smartphone use was objectively recorded using built-in screen-time tracking applications over seven consecutive nights. Morning resting heart rate and blood pressure were measured under standardized conditions using a validated automated sphygmomanometer. Data were analyzed using appropriate parametric or non-parametric tests, with statistical significance set at p < 0.05. Results: Baseline characteristics were comparable between groups, although the high-exposure group had a shorter mean sleep duration (p = 0.01). Morning resting heart rate was significantly higher in the high-exposure group compared to the low-exposure group (76.8 ± 6.9 vs 71.3 ± 6.1 beats/min; p < 0.001). Both systolic (121.6 ± 7.4 vs 116.2 ± 6.8 mmHg; p = 0.002) and diastolic blood pressure (78.4 ± 5.9 vs 74.9 ± 5.6 mmHg; p = 0.01) were also significantly elevated. Duration of pre-sleep smartphone use showed a moderate positive correlation with morning heart rate (r = 0.46) and systolic (r = 0.41) and diastolic blood pressure (r = 0.33) (all p < 0.01). Conclusion: Prolonged smartphone screen exposure before sleep is associated with higher morning heart rate and blood pressure in young adults, suggesting a potential adverse effect on cardiovascular regulation.

Smartphone use; Screen exposure; Heart rate; Blood pressure; Sleep hygiene