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Table 1 Demographical and clinical characteristics in adolescents with and without delayed sleep phase syndrome (DSPS) in the ung@hordaland study (n = 9,338)

From: Delayed sleep phase syndrome in adolescents: prevalence and correlates in a large population based study

  No DSPS (n = 9032) DSPS (n = 306)   
  %/mean (SD) %/mean (SD) P- level Cohen’s d
Age, mean 17.8 (0.8) 18.0 (0.8) .006 0.25
Girls, % 96.3%   3.7%   .007  
Boys, % 97.3%   2.7%    
Vocational situation, %      .153  
 In school 98.1%   99.3%    
 Trainee 1.3%   0.0%    
 Not in school 0.7%   0.7%    
Maternal education, %      .119  
 University/College 48.7%   51.4%    
 High school 41.4%   35.7%    
 Primary school 9.9%   12.9%    
Paternal education, %      < .001  
 University/college 43.1%   51.1%    
 High school 46.7%   33.5%    
 Primary school 10.3%   15.5%    
Parents live together, %      < .001  
 No 32.0%   46.3%    
Family economy      .006  
 Approx. like most others 67.8%   61.1%    
 Better economy 25.2%   27.7%    
 Poorer economy 6.9%   11.2%    
Current smoker 31.9%   35.9%   .225  
Ever tried alcohol 73.6%   87.6%   < .001  
Body mass index 22.2 3.6 22.2 3.5 .818 0.00
Insomnia, % 12.3% (32.8) 55.9% (49.7) < .001 1.04
Depression (total SMFQ score) 5.7 (5.7) 8.8 (5.9) < .001 0.53
Non-attendance, mean       
 Self-reported days* 1.4 (2.4) 2.3 (2.6) < .001 0.36
 Self-reported hours* 2.1 (3.2) 3.7 (3.9) < .001 0.45
 Number of days$ 3.9 (4.9) 7.1 (6.0) < .001 0.58
 Number of hours$ 7.2 (10.8) 15.4 (14.5) < .001 0.64
  1. *Last month.
  2. $Official register-based during last 6 months.