The purpose of this pilot experiment is threefold.

1. To assess the efficacy of the recruitment strategy
2. To assess the acceptability and feasibility of the outcome measurement methods obtained in free-living in the participants homes
3. To assess the acceptability of the prescribed interventions to reduce screen media use

Modern day's excessive use of screen-based media is heavily discussed in the public in terms of its possible harmful effects on physical and mental health among children and adults. To date there is little rigorously conducted research available on the effects of high use of todays screen-based media. Of particular notice, no controlled experimental studies in free-living have been carried out to study the immediate effects of screen-based media use on habitual physical activity patterns, sleep, and temporary stress- and emotional state.

To undertake a large-scale randomized controlled trial of the efficacy of limiting screen-based media use in families of parents and children the investigators aim to conduct a pilot study to assess the acceptability and feasibility of the outcome measurement methods obtained in free-living in the participants homes and the acceptability of the prescribed interventions to reduce screen media use. The investigators also perform the pilot study to investigate the efficacy of our recruitment strategy.

The participating families (households with children ≥4 and <18 years old) will be invited to answer a recruitment questionnaire sent out to their personal digital mailbox, which is a compulsory digital solution to receive mail from i.e. public authorities. Based on the survey answers eligible families (see section on inclusion/exclusion criteria) will be invited to participate in this pilot experiment. Families who are willing to participate will be randomized to one of two intervention groups after completion of the baseline measurement protocol. One group must reduce all recreational screen-based media use to less than three hours per week for a period of two weeks. Participants in this group will be asked to hand over their portable screen devices and in exchange they will be handed an old model Nokia phone. The other group must remove all screen-based media use (both work-related and recreational) after 6PM for a period of two weeks. The experiment does not include a control group. To ensure compliance to the interventions, the investigators will install an app, which will measure screen use on each participant's smartphone(s) and tablet(s). Furthermore, the investigators will connect a device to all televisions in each household, which will monitor television usage. To investigate the effect of the interventions all participants will go through a 7-day measurement protocol just before the family is randomized to one of the interventions and again during the last week of the intervention period.

Inclusion Criteria:

• High amount of screen-based media according to self-report (based on the adults only)
• In each household, at least one adult and one child must be above the 50th percentile for self-reported screen-based media use (characterized as "high" in this study). The 50th percentile is based on the responses from all adults who answered the recruitment survey.
• The children in the household are ≥ 4 and ≤ 18 years old, at the time the survey is sent out. In this way sleep measurements do not get distorted by infants and toddlers in the household (e.g. sleep).
• Adults and children who participate in the measurements must have the resources to remove all recreational- and work-/school-related screen-time in the evening hours, with a few exceptions, for a period of 2 weeks (intervention length).
• Participants must report that they consider the extent of their screen-based media use an issue
• Participants must report to be motivated to decrease screen-based media use for the whole family household.
• Family members who choose to not participate or are ineligible must be willing to support the success of this family experiment.

Exclusion Criteria:

• If the adults or children only reside in the household part time, i.e. have multiple addresses
• Diagnosis of stress from their general practitioner within the last year
• Diagnosis of sleep disorders from their general practitioner within the last year
• Working night shifts
• In any shape or form limited in one's ability to participate in habitual physical activity
• Has or is in inquiry of Neuropsychiatric disorders, such as Attention Deficit Hyperactivity Disorder (ADHD) or development disorders such as Autism.
• Already participating in research studies, such as the Odense Child Cohort