Many adolescents regularly use electronic devices, and a substantial proportion of adolescents use these devices in bed before they go to sleep. They are also at risk of using alcohol, recreational drugs, and tobacco, of becoming overweight or obese and having poor mental health. This thesis has investigated how adolescents' electronic device use affects their sleep and their wellbeing and examined (a) whether weekday and weekend sleep are explained using the same variables, (b) how device use affects sleep, and (c) how poor sleep affects mood. This thesis consists of three studies. Study 1 (N = 405) and study 2 (N = 489) both examined whether device use predicted poor and ill-timed sleep whilst simultaneously including other variables which are known to affect adolescents' sleep. Moreover, the studies also examined whether the factors which predicted weekday sleep also predicted weekend sleep. Thirdly, the studies examined the relationships between device use, sleep, and health related factors. The third study (N = 19) examined whether the blue light, content that was viewed on devices or the timing of device use affected adolescents' sleep and their following day mood.
This thesis has shown that adolescents' weekday and weekend sleep are explained differently. Adolescents who were more anxious or were more aroused had poorer weekday sleep and adolescents who socialised more at the weekend had poorer weekend sleep. Importantly, the thesis has shown that more frequent device use, later use of electronic devices and using more interactive content predict poorer sleep quality and ill-timed sleep. Finally, this thesis has shown that poor and ill-timed sleep predicted worse mood.
The findings from this thesis show that research should recognise that adolescents sleep differently on weekdays than they do at the weekend. The findings also show that researchers should investigate how the timing and content that individuals view on their electronic devices affects sleep
