More screen time, less sleep (probably due to less vitamin D)

Sleep and use of electronic devices in adolescence: results from a large population-based study

BMJ Open 2015;5:e006748 doi:10.1136/bmjopen-2014-006748

Mari Hysing1, Ståle Pallesen2,3, Kjell Morten Stormark1, Reidar Jakobsen1, Astri J Lundervold1,4, Børge Sivertsen5,6,7

1Regional Centre for Child and Youth Mental Health and Child Welfare, Uni Research Health, Bergen, Norway

2Department of Psychosocial Science, University of Bergen, Bergen, Norway

3Norwegian Competence Center for Sleep Disorders, Haukeland University Hospital, Bergen, Norway

4Department of Biological and Medical Psychology, University of Bergen, Bergen, Norway

5Division of Mental Health, Norwegian Institute of Public Health, Bergen, Norway

6Uni Research Health, Bergen, Norway

7Department of Psychiatry, Helse Fonna HF, Haugesund, Norway

Correspondence to: Dr Mari Hysing; mari.hysing@uni.no

Received 26 September 2014, Revised 28 November 2014, Accepted 2 December 2014, Published 2 February 2015

* Study took place at 60 degrees North Latitude - which gets little sun/vitamin D * Vitamin D is not mentioned once in the publication * VitaminDWiki predicts re-analysis of the data will get even stronger relationship if look at: *    Winter season *    Dark skin - lower level of vitamin D *    Obese - Vitamin D is stored in fat and not available to the body See VitaminDWiki * Sleep longer if have more vitamin D – many studies *    Vitamin D was the only statistically significant predictor in the blood of longer sleep * 2nd study on same page: 2.2X more likely to sleep < 5 hours if low vitamin D *    vs 2.7 X in study on this page * Sleep disorders cured by 60-80 ng of vitamin D and some B vitamins – March 2013 * Supplementing with Vitamin D might be a cure for screen time/sleep problems. * Does Less Sun Mean More Disease? 5 minute video has the following * Dark skinned teens use media much more - June 2011 has the following graphic 1. See also web * Poor Sleep May Spur College Weight Gain NYT Oct 2015 * Increased screen time and lower vitamin D NOT mentioned

Objectives Adolescents spend increasingly more time on electronic devices, and sleep deficiency rising in adolescents constitutes a major public health concern. The aim of the present study was to investigate daytime screen use and use of electronic devices before bedtime in relation to sleep.

Design A large cross-sectional population-based survey study from 2012, the youth@hordaland study, in Hordaland County in Norway.

Setting Cross-sectional general community-based study.

Participants 9846 adolescents from three age cohorts aged 16–19. The main independent variables were type and frequency of electronic devices at bedtime and hours of screen-time during leisure time.

Outcomes Sleep variables calculated based on self-report including bedtime, rise time, time in bed, sleep duration, sleep onset latency and wake after sleep onset.

Results Adolescents spent a large amount of time during the day and at bedtime using electronic devices. Daytime and bedtime use of electronic devices were both related to sleep measures, with an increased risk of short sleep duration, long sleep onset latency and increased sleep deficiency. A dose–response relationship emerged between sleep duration and use of electronic devices, exemplified by the association between PC use and risk of less than 5 h of sleep ( OR=2.70 , 95% CI 2.14 to 3.39), and comparable lower odds for 7–8 h of sleep (OR=1.64, 95% CI 1.38 to 1.96).

Conclusions Use of electronic devices is frequent in adolescence, during the day as well as at bedtime. The results demonstrate a negative relation between use of technology and sleep, suggesting that recommendations on healthy media use could include restrictions on electronic devices.

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