Date Published: October 16, 2018
Publisher: Public Library of Science
Author(s): Naja Hulvej Rod, Agnete Skovlund Dissing, Alice Clark, Thomas Alexander Gerds, Rikke Lund, Jacobus P. van Wouwe.
Round-the-clock use of smartphones holds a potential for awakenings and/or shorter sleep duration, which may have adverse health consequences. We aim to describe overnight smartphone activity among young adults and to characterize those with smartphone interrupted sleep in terms of sleep impairment and mental and physical health indicators.
We use unique objective high-resolution information on timing of smartphone activity (based on >250,000 phone actions) continuously monitored over a four-week period among 815 young adults combined with indicators of mental and physical health.
We find substantial overnight smartphone activity. More than 12% had smartphone activity in the middle of the night (3 to 5 hours after self-reported bedtime) and 41% had smartphone interrupted sleep on at least one weekday during a 4-week period. Those with frequent smartphone interrupted sleep had on average 48 minutes shorter self-reported sleep duration and higher body mass index, whereas there were no differences in physical or mental health symptoms.
The substantial smartphone activity during bed hours among young adults may pose a public health challenge and especially the relation to overweight warrants close attention.
Bip…zzzz…bip…zzz…bip…zz…bip…z…! Being awakened during sleep is a well-known method used in experimental sleep studies to show adverse health consequences of sleep deprivation and impaired sleep quality, and such experimental studies have rather consistently shown detrimental effects on physiological and mental functioning following sleep interruptions [1,2].
We find substantial overnight smartphone activity in a unique dataset with objective information on duration and timing of smartphone activity in 815 young adults continuously monitored for four weeks. While smartphone activity around bedtime and awakening is expected, it is striking that more than 12 percent have smartphone activity in the middle of the sleep period and that 41% have smartphone interrupted sleep on at least one weekday during a four-week period. Those with frequently interrupted sleep had shorter self-reported sleep duration and higher body mass index. Apart from this there were no major differences in physical or mental symptoms according to the level of smartphone interrupted sleep.
We document substantial overnight smartphone activity in young adults, but it is unclear whether this smartphone activity is causing sleep interruption or if it is used as an entertainment device among those with sleep impairment due to other causes. It is, however, striking that more than one third of the young adults in the study had smartphone interrupted sleep during at least one weekday within a four-week period. Those with frequently interrupted sleep had shorter self-reported sleep duration and higher body mass index. There were no clear relations to other physical or mental health symptoms. Improving sleep hygiene through better management of technology, including advice to set limits for accessibility during the sleep period, may improve health and well-being in the general population.