How SMART is it to go to bed with a PHONE?

The present proposal aims to examine the impact of smartphone usage during bedtime on sleep and memory consolidation in an adolescent population. Currently, many studies show a considerable influence of a certain wave-length light (about 480nm, blue-light) on the human sleep-wake cycle. This specific light is used in the screens of mobile devices such as smartphones, tablets and laptops. The eye is very sensitive to this wavelength of light which activates the mechanism that causes us to wake up and be attentive. Therefore, we assume that smartphone use during bedtime has a negative effect on sleep and especially on sleep-dependent memory consolidation in adolescents. 60 adolescents aged between 16-18 years will take part in the study. The duration of the experiment will be five weeks in total, including three adaptation and three experimental nights. During the whole period of the study, i) the sleep-wake cycle of the adolescents will be monitored with sleep logs and actigraphy, and ii) smartphone-use will be tracked with a mobile device application. During the laboratory nights, polysomnography, body temperature, salivary melatonin/cortisol (i.e., hormones controlling our sleep-wake-cycle and stress regulation) levels and stress as well as affect states will be measured. Light stimulation will take place during the last 2h before falling asleep. All adolescents will participate in the following experimental light-conditions in a randomized order each separated by one week: (i) NORMAL, (i.e., smartphone use with regular screen, rich with blue-light waves), (ii) FILTER, (i.e., orange-tinted blue-light filter application), and (iii) ZERO (no smartphone use 2h before falling asleep). To investigate the impact of smartphone use before falling asleep on memory consolidation processes, we will assess performance in a word-pair associate task before and after sleep. In general, we expect blue-light exposure during bedtime to have a negative impact on sleep. More precisely, we assume that use of blue-light devices (i) reduces the duration of the deep sleep phase as well as REM sleep and thereby reduces the restorative effect of sleep, (ii) leads to an attenuation of the evening increase in melatonin and subjective sleepiness as well as an increase in individual stress levels as well as negative affect scores, and (iii) decreases memory storage during sleep. The projects outcomes are bound to result in ground-breaking scientific papers worthy of publication in international journals. They will contribute to our mechanistic understanding of the impact of technology in the bedroom to adolescents sleep, memory consolidation and emotion regulation a question that has never been so timely. Adolescents in industrializes nations are well known to be the most sleep-deprived population in society with currently limited knowledge of these effects on their cognition and well-being. We are convinced that our research proposal will offer significant and highly relevant scientific output that is further echoed by immense societal relevance. Besides our basic research approach, we seek to achieve scientific insights and recommendations for handling smartphone use during bedtime by adolescents, which will be additionally useful for educational programs at schools and for parents

How SMART is it to go to bed with a PHONE? The impact of blue-enriched smartphone light exposure before falling asleep on sleep-dependent memory consolidation The use of electronic devices with blue-enriched light emitted by LED screens for reading, communication and entertainment has increased tremendously, especially among children and adolescents. According to a survey conducted by Common Sense Media, 40% of adolescents and 26% of parents in the U.S. check their smartphones within five minutes of going to bed, and a significant proportion even use their mobile devices in the middle of the night. Accumulating empirical evidence suggests that blue light exposure before bedtime disturbs sleep functions. In this project, we investigated whether evening exposure to short-wavelength light from smartphones affects adolescents and young adults differently, not only with respect to acute sleepiness and melatonin suppression, but also in terms of effects on sleep architecture and physiology, in particular sleep-related memory consolidation. We exposed 33 adolescents and 35 adults to three different light conditions in the late evening, each varying in the amount of short-wavelength light emitted (i.e., reading from a printed book or reading from a smartphone either with or without a blue light filter). We observed the lowest melatonin levels after 90 minutes of reading on the smartphone without a blue light filter, while melatonin levels were highest in the book condition. Notably, in adults, this suppression of melatonin after smartphone reading persisted for the next 50 minutes before bedtime. However, adolescents fully recovered from this suppression and showed comparable melatonin levels in the three light conditions at bedtime. Consequently, the observed effects on subsequent sleep were only seen in adults, resulting in a slight reduction in the percentage of N3 sleep during the first quarter of the night. Importantly, total night sleep and adolescent's sleep were unaffected by the light conditions. Sleep-dependent memory consolidation, assessed both behaviorally by a declarative word-pair learning task and physiologically by analysing the coupling between slow oscillations and sleep spindles, was also unaffected. Overall, the results of this project contribute to our mechanistic understanding of the impact of bedroom technology on sleep and memory consolidation in adolescents and young adults - a question that has never been more relevant. Adolescents in industrialized nations are known to be the most sleep-deprived population in society, with limited understanding of how this affects their cognition and well-being. Our research empirically supports general sleep hygiene advice and can inform future recommendations regarding the handling of LED-screen device exposure before bedtime.Therefore, we are currently running workshops in schools on "healthy sleep and smartphone use" implemented as an outreach project funded by one of the Austria's major health insurance companies (Österreichische Gesundheitskasse).