Nocturnal use effect of smartphone on sleep-wake cycle, autonomic response and morning cognitive processing of university students
Adolescents, sleep-wake cycle, smartphone use, cognitive processing, autonomic response.
University experience promotes major changes in the lives of emerging adults. In relation to media use, college students report greater media use compared to high school students. The multi-task capacity and small and practical dimensions of smartphones raise interest rates and increase light exposure at night, sleep irregularity and deprivation. Sleep irregularity and deprivation affect the basic cognitive processes that regulate the performance of individuals, such as attention, operational memory, inhibitory control, and cognitive flexibility. However, some researches suggest that performance and somnolence might suffer a compensatory effect of the activation of other brain areas on the impairment caused by sleep deprivation. Recent research has identified Locus ceruleus as a possible promoter of this compensatory effect, which can be measured in cortical and autonomic activity. In this work, we evaluated the impact of smartphones nocturnal use over sleep parameters and cognitive performance. In parallel, the masking effect of the hyperactivity of the autonomic nervous system on the damages caused by sleep deprivation was evaluated through autonomic measures. From the planned sample of 150 students, 45 completed questionnaires assessing socioeconomic status, nighttime smartphone use, chronotype, sleep quality and daytime sleepiness. In addition, they filled out the sleep diary and used the actigraphs for 10 days. At this stage, they performed cognitive tests and the collection of autonomic response variables once between 7 and 9 h. At the weekend, the bedtime (F (1,430) = 14.57, p <0.005) and wakeup time (F (1,431) = 53.11, p <0.005) were later, time in bed was higher F (1,430) = 12,10, p <0.005) and sleepiness on awakening, lower (F (1,426) = 8.29, p = 0.004). Participants were divided into 2 groups according to the duration of the smartphone use after 6:00 pm. The group of greater use reported later bedtime (F (1,430) = 8.61, p <0.005), shorter time in bed (F (1,430) = 11.64, p <0.00), and greater sleepiness at awakening (F (1.426) = 18.83, p <0.001). In addition, the frequency of poor sleep quality was higher (X² = 103.81, p <0.001). There were no differences between the groups for the components of attention. The data collected for the other cognitive functions, autonomic measures and actimetry are under analysis. It is necessary to enlarge the sample to confirm the observed results.