Parents who let kids use phones in bed could be dooming their sleep health
By Study Finds
For years, parents and health experts have warned teens about the dangers of using screens before bedtime. The common wisdom has been that scrolling through social media or watching videos late at night disrupts sleep and leads to tired, cranky kids the next day. However, a new study suggests this advice may need updating.
Researchers in New Zealand found that screen time in the two hours before bed had little impact on adolescents’ sleep. What mattered more was using screens after getting into bed. The study, published in JAMA Pediatrics, provides a nuanced look at how different types of screen use affect sleep in young people.
The research team, led by Dr. Bradley Brosnan at the University of Otago, studied 79 adolescents between 11 and 14 years-old. They used wearable cameras to capture detailed information about participants’ screen use in the evenings. Unlike previous studies that relied on self-reported data or focused only on smartphones, this approach allowed researchers to observe all types of devices and screen activities.
Participants wore the cameras for four non-consecutive nights over the course of a week. The cameras recorded their screen use from two hours before bedtime until they attempted to fall asleep. A stationary camera in the bedroom captured any screen use after the teens got into bed.
The results challenged some long-held assumptions. Screen time in the two hours before bed didn’t significantly affect most measures of sleep health. On average, teens spent about 56 minutes using screens during this period. While screen use was associated with later sleep onset, it was matched by later wake times, resulting in no change to overall sleep duration.
However, using screens after getting into bed was linked to shorter sleep duration. On average, participants spent 16 minutes using screens while in bed before attempting to sleep. For every 10 minutes of screen time during this period, total sleep time decreased by three minutes.
The type of screen activity also mattered. Interactive screen use, such as gaming or multitasking across multiple devices, was particularly disruptive. For every 10 minutes of interactive screen time in bed, sleep duration decreased by 9 minutes. Even passive activities like watching videos were associated with shorter sleep, though to a lesser extent.
“It quickly became obvious that adolescents spend a lot of their screen time while in bed,” Dr. Brosnan says in a statement. “Our most interesting findings were that this screen time before they got into bed had little impact on sleep that night. However, screen time once in bed did impair their sleep – it stopped them from going to sleep for about half an hour, and reduced the amount of sleep they got that night.”
These findings suggest that current sleep hygiene recommendations, which often advise against all screen use in the hour before bed, may need refinement. Dr. Brosnan and his colleagues argue for a more nuanced approach that recognizes the reality of adolescents’ screen use habits.
The study also highlighted the importance of distinguishing between different periods of evening screen use. The interval between getting into bed and attempting to sleep – what researchers call “shut-eye latency” – emerged as a crucial period. Screen use during this time was more strongly associated with reduced sleep than use earlier in the evening.
Interestingly, the study found no significant link between screen use and sleep quality measures like how long it took participants to fall asleep once they tried or how often they woke up during the night. This suggests that screen time primarily affects sleep by delaying bedtimes rather than disrupting sleep itself.
The researchers also examined whether following current guidelines about stopping screen use 30, 60, or 120 minutes before attempting sleep made a difference. They found no association between time since the last screen use and any sleep measure, further challenging existing recommendations.
While the study provides valuable insights, it’s important to note its limitations. The sample size was relatively small and participants’ parents were highly educated, which may limit how widely the results can be applied. The study also focused on a narrow age range before significant shifts in sleep preferences typically occur in late adolescence.
Despite these caveats, the findings offer food for thought for parents, health professionals, and policymakers. They suggest that a one-size-fits-all approach to screen time and sleep may not be the most effective. Instead, focusing on reducing screen use once in bed, particularly interactive activities, could be a more practical and impactful strategy for improving adolescent sleep.
“Our findings suggest that the impact of screen time on sleep is primarily through time displacement delaying sleep onset rather than any direct effects of blue light or interactive engagement as we didn’t find associations with sleep latency and wakefulness during the sleep period,” says Brosnan. “We need to revisit sleep guidelines, so they fit the world we live in, and actually make sense – the current ones aren’t achievable or appropriate for how we live.”
Paper Summary
Methodology
The researchers used a combination of wearable cameras, stationary bedroom cameras, and wrist-worn accelerometers to gather data. Participants wore the cameras for four nights over a week, capturing their screen use from two hours before bedtime until they tried to sleep. The bedroom camera recorded any screen use after getting into bed. Accelerometers measured sleep duration and quality. This approach allowed for objective measurement of both screen time and sleep patterns, providing a more accurate picture than self-reported data.
Key Results
The study found that screen use in the two hours before bed didn’t significantly affect overall sleep duration. However, using screens after getting into bed was associated with shorter sleep. Interactive screen activities, like gaming or multitasking, were particularly disruptive. For every 10 minutes of interactive screen time in bed, sleep duration decreased by 9 minutes. Even passive screen use in bed was linked to shorter sleep, though less dramatically.
Study Limitations
The study had a relatively small sample size of 79 participants, and their parents were highly educated, which may limit how widely the results can be applied. The age range studied (11-14 years) was narrow, missing potential changes in sleep patterns that occur in later adolescence. The study also can’t rule out all possible confounding factors that might influence the relationship between screen use and sleep.
Discussion & Takeaways
The findings challenge the conventional wisdom that all screen use before bed is harmful to sleep. They suggest that current sleep hygiene guidelines may need updating to focus more on limiting screen use once in bed, particularly interactive activities. The study highlights the importance of the “shut-eye latency” period – the time between getting into bed and attempting to sleep – as a crucial window for sleep health. The researchers argue for a more nuanced approach to screen time recommendations that aligns with the reality of how adolescents use technology.
Funding & Disclosures
The study was funded by Lotteries Health Research. One of the researchers, Prof Taylor, was supported by the Karitane Fellowship. The authors reported no conflicts of interest.
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