Night-time mobile phone use has the potential to detract from sleep quality and continuity, resulting in tiredness and impaired psychological function. An on-line survey of the mobile phone habits of 397 adults (M age = 34.45, SD = 13.29) revealed that 75% used a mobile phone after lights out at least once a month, with 12.8% making calls at any time of night. More than 50% of participants reported being woken by the phone use of other people sharing their sleeping space. Using the phone after lights out and a general unwillingness to turn the phone off made a small but significant contribution to the level of tiredness. Tiredness made a significant contribution to DASS scores, with higher levels of tiredness being associated with more depression, anxiety and stress. Objective measures of sleep fragmentation and phone use along with diary recordings of participants' evaluations of the affective value of each call or text, would be valuable in the exploration of the impact of night time phone use on tiredness and psychological function.