4. Discussion
This study suggests that use of a mobile phone, particularly a smartphone, as an alarm clock is associated with significantly greater personal mobile phone use (about 14.97 h per week, compared to 8.15 h for those with an actual alarm clock). Thus, substituting a smartphone for an alarm clock is associated with 1.8 fold increase in leisure time spent using a mobile phone. As the Supplementary material shows, similar trends can be observed for all leisure-based Internet use (including Internet use on personal computers). As this study is correlational in nature, causal relationships cannot be inferred; thus, we cannot say that non-use of analogue alarm clocks leads to elevated mobile phone use or Internet consumption. Indeed, the converse may also be true, i.e.