Demi?rci?, Akgönül, & Akpinar (2015) conducted a research on relationship of Smartphone Use Severity with Sleep Quality, Depression, and Anxiety in 319 male & female University Students. The participants were divided into three groups – a smartphone non-user group, a low smartphone use group and a high smartphone use group. The Pittsburgh Sleep Quality Index, Beck Depression Inventory, Beck Anxiety Inventory and the Smartphone Addiction Scale were administered to the participants. Findings of the study indicated that smartphone overuse may be associated with depression, anxiety, and poor sleep quality.
Amra, et.al (2017) conducted a study to investigate the relationship of late-night cell phone use with sleep duration and quality in a sample of Iranian adolescents. 2400 samples were chosen for the study aged between 12-18 years. Data regarding age, body mass index, sleep duration, cell phone use after 9 p.m., and physical activity were documented and sleep was assessed using the Pittsburgh Sleep Quality Index questionnaire. Result of the study indicated that 1270 participants reported that they use their cell phone after 9 p.m and 56.1% of girls and 38.9% of boys reported poor quality of sleep. Findings of the study indicated that late-night cell phone use by adolescents was associated with poorer sleep quality and Participants who were physically active had better sleep quality and quantity.