This study utilized research gotten on Korean National Health insurance and Nutrition Test Survey (KNHANES). Information regarding the analysis build and methods are supplied in other places (Kim mais aussi al. 2013b ; Park 2013 ). Temporarily, the KNHANES was a national, population-created get across-sectional data which had been held by the Korean Ministry out-of Fitness and you will Passion and also the Division out-of Chronic Disease Security, Korean Cardiovascular system having Situation Control and you can Protection. This new KNHANES adopted a going sampling framework which had been a great stratified, cutting-edge, multistage, opportunities, party survey that have proportional allocation according to research by the National Census Registry with the non-institutionalized civil people out-of Korea. Data regarding next KNHANES (2008–2009) and you can fifth KNHANES (2010–2012) were used to estimate new organization anywhere between bed period and you will myopia. On newest investigation, 3846 some one old a dozen–19 decades have been selected. Ones, 144 victims exactly who don’t statement bed period and you can 77 sufferers who did not undergo refractive error examination have been excluded. Finally, 3625 people old a dozen–19 years had been as part of the data. The analysis structure adopted the fresh principles of one’s Statement away from Helsinki to possess biomedical search. The analysis protocols had been approved by the Institutional Opinion Panel from this new Catholic College or university regarding Korea for the Seoul, Korea. Most of the users considering created informed consent.
Ophthalmology citizens otherwise ophthalmologists counted refraction in the place of cycloplegia of your best eyes using an enthusiastic autorefractor (KR-8800 ® ; Topcon, Tokyo, Japan). Refraction measurements was basically changed into round equivalents, that happen to be determined since the spherical worth in addition to half the astigmatic really worth. Myopia are identified as ??0.fifty dioptres (D) and you will www.datingranking.net/nl/getiton-overzicht/ high myopia try recognized as ??six.0 D.
Group information was amassed throughout the a medical interviews. Peak and you will weight was indeed measured because subjects was in fact wear light dresses instead shoes. The human body bulk list (BMI) is determined as follows: weight (kg)/level (m) 2 . Sleep are counted because the mediocre sleep days daily playing with a home-said approach. The players was basically expected: ‘Normally, how long would you sleep everyday?’ The learning number of the players is classified into the an excellent scale of just one to three, as follows: 1, elementary degree otherwise less; 2, secondary school graduate; and step three, high-school graduate. Economic status was classified toward 4 quartiles, that has been according to family yearly earnings. This new physical working out top is estimated just like the actual months per week out of energetic-, moderate- and you may lightweight-strength (walking) craft ?20 minute/time. Strenuous physical working out was defined as you to required more difficult than normal breathing for at least 20 minute at a time. Examples are running, walking and you can hiking, heavy lifting, timely bicycling otherwise diving, and you will to experience feet baseball, basket ball or men and women tennis. Reasonable physical working out was requisite somewhat more challenging than usual respiration to own about 20 min simultaneously. Analogy affairs include training white loads; meagerly paced swimming; and you may to relax and play volleyball, otherwise increases tennis, badminton or ping pong. Mild-power passion are walking no less than 10 min at the same time.
Statistical analyses was performed making use of the Statistical Bundle to the Social Sciences ( spss observar. 18.0; SPSS, Inc., Chicago, IL, USA) to help you take into account the brand new advanced sampling build. Strata, sampling units and you can testing weights were used to obtain unbiased point rates and robust linearized important mistakes. Fellow member services was described utilising the means and you may important problems to have continuous parameters and the rates and simple problems to own categorical variables, with regards to the presence out-of myopia. Study off variance or the chi-square take to was applied examine new demographic characteristics.
First, simple and multiple linear regression analyses were used to evaluate the association between sleep duration and refractive errors. Second, to evaluate the effect of sleep duration (hr) on the prevalence of myopia, simple and multiple logistic regression analyses were used. After calculation of the sex- and age-adjusted odds ratio (OR) (Model 1), we adjusted for age, sex and other confounders, including education levels, economic status, height and physical activity, which were established as independent risk factors in previous studies (Model 2) (Zhang et al. 2011 ; Pan et al. 2012 ; Kim et al. 2013a , b ). Finally, sleep durations were classified into five categories: <5, 6, 7, 8 and >9 hr. Then, simple and multiple logistic regression analyses were used to examine the effect of deficient or excessive sleep on myopia. All variables for logistic regression analysis were examined for multicollinearity, and only variables with a variance inflation factor <10 were used. p values were 2-tailed, and <0.05 was considered to indicate statistical significance.