New research suggests that adults who use mobile phones or tablets right before bed are more likely to experience poor sleep.
The study, published in JAMA Network Open, challenges the notion that screen-related sleep disruption primarily affects younger demographics.
Researchers from the American Cancer Society analysed data from over 122,000 participants in the US and Puerto Rico, focusing on sleep habits and screen use (excluding television) during the hour before sleep.
The study found that approximately 41 per cent of participants used screens daily before bed, while 17 per cent reported no screen time at all in that time.
The findings revealed a significant correlation between pre-sleep screen use and reduced sleep quality.
Individuals who reported daily screen use were 33 per cent more likely to report poor sleep quality compared to those who avoided screens before bed.
Additionally, daily screen users tended to have later bedtimes.
The study also noted that 58 per cent of participants were identified as “morning larks”, individuals naturally inclined to be more active earlier in the day.
Overall, people who used screens before bed each day had 48 minutes less sleep every week.
The light from the screens may play a part, the authors suggested.
“Light exposure at night can disrupt sleep by disrupting this natural cycle through delaying the onset of melatonin,” they wrote.
“This can lead to reduced sleepiness and increased alertness.”
But they said that disruptions to sleep due to screen use “may not be limited to effects of screen light”, adding: “It is not only the light being emitted from these devices that needs to be considered, but the content as well”.
They said that social media is one of the major sources of content being consumed on mobile devices but “only a handful of studies have looked at social media use at bedtime”.
Associations between screen time and poor sleep appeared to be more pronounced among night owls – or people categorised as evening chronotypes, who are more active later in the day.
The researchers said night owls are already at risk of poor sleep due to “social jetlag” or the “misalignment between circadian rhythms and social commitments”, meaning that night owls would prefer to sleep in later but cannot because of work or school.
The team found that morning larks who used a screen before bed went to bed 9.33 minutes later on workdays compared with those who kept screens out of the bedroom.
And night owls went to bed 15.62 minutes later on workdays. Results were similar for non-workdays.
The authors concluded: “Our findings strengthen the evidence that electronic screen use and disruptions to sleep duration and quality are not limited to children and adolescents but to the broader adult population as well.
“The decrease in quality and duration appeared to be greater among those with a later chronotype and may be due to delayed bedtimes.
“Continued work is needed to understand the mechanisms through which screen use disturbs sleep (eg, artificial light at night vs content), especially among individuals with later chronotypes who are already at increased risk of poor sleep due to work and social commitments necessitating earlier wake times.”
