Electronic media use is becoming an increasingly important part of life for today's school-aged children. At the same time, concern of children's sleep habits has arisen, and cross-sectional studies have shown that electronic media use is associated with short sleep duration and sleep disturbances. The purpose of this longitudinal study was to investigate whether baseline electronic media use and media presence in a child's bedroom predicted sleep habits as well as changes in these sleep habits 18 months later among 10- to 11-year-old children in Finland.
The school-aged children (n=353, 51% girls) from 27 schools answered a questionnaire in 2006 and again 2008 in the Helsinki region of Finland. Electronic media use was measured by computer use and TV viewing. Media presence in a child's bedroom means the presence of a TV or a computer in a child's bedroom. Sleep habits were measured by bedtimes on school days and at the weekend days, sleep duration, discrepancy of bedtimes, and discrepancy of sleep duration between school days and weekends. Linear regression analyses were used to examine whether electronic media use and media presence predicted sleep habits with adjustments for grade, family structure, and baseline sleep. Gender differences were also examined.
The children used a computer for one hour per day and watched TV over one hour a day in 2006. They slept over nine hours on school days and over ten hours at the weekends in 2008. Computer use and television viewing predicted significantly shorter sleep duration (p
This study investigated gender-specific interaction between effort-reward imbalance and video display unit (VDU) postural risk factors at work on the incidence of self-reported musculoskeletal symptoms in the shoulder-neck, lower back and upper limbs regions.
A cohort of 2,431 VDU users - consisting of white-collar workers in three Canadian public service organizations - was assessed on postural risk factors and effort-reward imbalance at work.
After a mean follow-up time of three years, the six-month incidence proportion of musculoskeletal symptoms in each body region was measured. Interaction was estimated with the attributable proportion of cases due to interaction.
For women, two significant attributable proportions due to interaction between effort-reward imbalance and postural risk factors were observed in the shoulder-neck (64%) and upper limbs (57%) regions, while an interaction of 25%, although not significant, was observed in the lower back. No interaction was observed for men.
This interaction means that, among women, when effort-reward imbalance and postural risk factors are simultaneously present, the incidence of musculoskeletal symptoms is greater than the sum of effects of the individual factors. Successful interventions on either one of these exposures would thus have the supplemental benefit of preventing cases due to interaction.