Short summary

Over the last decade, profound changes have taken place in technology of screen media and how it is used. The possible harmful effects of exessive screen media use on young people and adults has not been investigated in well controlled randomized experiments. The present study aims to investigate the short-term effect of limiting habitual (free-living) use of screen-based media, and timing of limiting use, on physical activity patterns, circadian rhythm, and sleep in a randomized trial in families of children and parents that have excessive use of screen media  

Rationale

Today's population-wide excessive use of screen-based media is heavily discussed in the public in terms of its possible harmful effects on physical and mental health in young people and adults and is considered an emerging public health concern. To date there is limited evidence from experimental studies on the effects of today's excessive habitual screen-based media use, and this scarcity severely hinders our basic causal understanding of the plausible effects on circadian rhythm and sleep patterns, habitual physical activity, and physiological stress. The present study aims to investigate the short-term effect of limiting habitual (free-living) use of screen-based media, and timing of limiting use, on physical activity patterns, circadian rhythm, and sleep in a randomized trial in families of children and parents that have excessive use of screen media. Participants will be recruited via a survey that will be sent out to households in families residing in municipalities of Funen, where one adult at minimum and at least one child between the age of 6 and 10 resides. Only one adult and one child between 6-10 years of age will be included in the survey. The parent reported survey will include questions about screen-time behavior, willingness to join an experiment to reduce screen media use, and the participants are encouraged to install an application for IOS and Android devices, which quantify the screen activity of tablets and smartphones. Based on the survey, eligible parents and children will be recruited to a 2-week three-arm randomized experiment conducted under free-living conditions. After baseline measurements families will be randomized to a control group, a group that removes recreational screen media use, or a group that removes recreational screen media use in the evening in 1:1:1 ratio. An expected total of 90 families will be recruited. Outcome measures include habitual physical activity, heart rate variability, sleep, saliva cortisol, circadian rhythm, and self reported mental health. A pilot study in one municipality will be carried out to evaluate the recruitment strategy and the feasibility of the measurements and compliance to the intervention and to estimate the necessary sample size in the study.  

Description of the cohort

Family households of 1-2 adults and 1-2 children 6 to 10-years of age, all of whom reside on the same address and registered on this address only. All invited participants will reside in municipalities on Funen.

Data and biological material

Children and parents:

Sleep (EEG-based objective measurements), heart rate variability (24-hour recordings), combined hip- and waist worn accelerometry for assessment of physical activity, self-reported measures, objective assessment of screen media use (app-based and device monitoring) 

Parents only:

Salivary cortisol and cortisone

Collaborating researchers and departments

Department of Sports Science and Clinical Biomechanics, University of Southern Denmark

• Associate professor Anders Grøntved
• Post doc Line Grønholt Olesen
• Ph.d scholar Martin Gillies Rasmussen
• Associate professor Peter Lund Kristensen
• Post doc Jan Christian Brønd
• Research assistant Jesper Pedersen
• Assistant professor Heidi Klakk Egebæk