A good bedtime routine can be the difference between a restful or restless night — and one key habit may be severely impacting some adults’ sleep, a study suggests. Research found that adults who used a mobile phone or tablet directly before going to bed experienced poorer quality sleep and reduced sleep time.
A team led by experts from the American Cancer Society said their findings show that sleep problems linked to screens do not just affect children and teenagers. The study gathered data on sleeping habits and screen use — not including television — in the hour before sleep from more than 122,000 people from the US and Puerto Rico. Around 41% admitted to using their screens, while 17% said they did not use screens shortly before bed, and the rest said they occasionally did.
Compared with people who did not use phones or tablets before bed, people who reported daily use were a third more likely to report having poor sleep quality.
Screen users were also more likely to go to bed later and had 48 minutes less sleep every week.
Suggesting reasons for the trend, the researchers wrote in the journal JAMA Network Open: “Light exposure at night can disrupt sleep by disrupting this natural cycle through delaying the onset of melatonin. 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.”
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”, the authors noted.
The study also found that 58% of participants were so-called morning larks, or people who have the innate inclination to be more active earlier in the day.
The link between screen time and poor sleep appeared to be stronger among night owls who are more active later in the day.
Night owls are already at risk of poor sleep due to “social jetlag” or the “misalignment between circadian rhythms and social commitments”, the researchers said, meaning they would prefer to sleep in later but cannot because of work or school.
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.”
