The study came out with a conclusion suggesting that 39% of young adults may be addicted to their phones and suffer poor sleep because of it. It took into account the number of hours the participants were using their phones each day, measured sleep patterns, and noted decreases in socializing as well as negative feelings such as anxiety when the subjects were away from their smartphones.
The study states:
The overall prevalence of smartphone addiction was 38.9% (95%CI: 35.9–41.9%; n = 406/1,043). This includes 35.7% of males who were addicted and 40.1% of females (Table 3). For participants aged under 21 years, 42.2% exhibited smartphone addiction, compared to 34.2 and 28.0% of participants aged 22–25 years, and over 26 years, respectively. Of participants who used their smartphone for 2 or less hours per day, 20.3% were addicted, compared to 53.9% of those who used it for more than 5 h. Of those that stopped using their device more than an hour before bedtime, 23.8% exhibited addiction, compared to 42.0% of those stopping <30 min before bedtime.""
The study claims that "validated addiction instrument should be used to capture this phenomenon [of addiction]." University College London seems to have done their best to use professional and certified indexes to objectively measure each factor that was used to diagnose what constituted "addiction," and references 47 other formerly published studies on the subject. If nothing else, the study should at least bring awareness to how much we are staring down at a screen when we could be doing better things, and the study objectively correlates that more screen time (especially later at night) leads to poorer sleep—which we can probably all work to improve.