Table 1 Characteristicsa of n = 213 adolescents (age 9–18 years, N = 572 questionnaires) at first and last measurement over a maximum of 5 years follow-up, DONALD Study, 2015–2019b.

From: Changes in chronotype and social jetlag during adolescence and their association with concurrent changes in BMI-SDS and body composition, in the DONALD Study

Variable

First measurement

Last measurement

Female n (%)

95 (45)

 

Follow-up (years)c

2.1 (1.9–3.3)

 

Age (years)

12.9 (11.0, 15.0)

15.1 (14.6, 18.0)

Pubertal markers

 Growth curves

 Age at take-off (years)

9.7 (8.1, 10.6)

 

  ♂

10.5 (9.8, 11.2)

 

  ♀

8.0 (7.4, 8.7)

 

 Age at peak height velocity (years)

12.8 (11.3, 14.0)

 

  ♂

13.6 (12.9, 14.6)

 

  ♀

11.2 (10.5, 11.9)

 

Anthropometric data

  

  BMI (kg/m2)

19 (17, 22)

20 (18, 23)

  BMI-SDS (kg/m2)

−0.01 (−0.69, 0.76)

0.05 (−0.70, 0.80)

  FMI (kg/m2)

4 (2, 5)

4 (3, 6)

  FFMI (kg/m2)

15 (14, 16)

16 (15, 17)

  Overweight (yes)d

33 (15)

28 (13)

Chronobiological variables (hh:mm)

  MSFsc

3:28 (3:02, 4:15)

4:07 (3:23, 5:00)

  Social Jetlag

1:45 (1:15, 2:25)

2:02 (1:28, 2:45)

  Sleep onset week

21:55 (21:12, 22:40)

22:28 (21:30, 23:10)

  Sleep onset weekend

00:22 (0:01, 0:23)

00:04 (0:01, 00:23)

  Total sleep duration week

08:25 (7:35, 9:10)

07:40 (7:00, 8:30)

  Total sleep duration weekend

09:45 (8:50, 10:30)

09:00 (8:25, 09:55)

  Wake up alone during weekend

182 (85)

186 (87)

Season of chronotype assessment

  Spring

46 (21)

44 (21)

  Summer

61 (28)

69 (32)

  Autumn

56 (25)

49 (23)

  Winter

50 (25)

51 (24)

Other risk factors

  Total Energy Intake (kcal/d)

1829 (1558, 2130)

1831 (1558, 2210)

  Physical activity (kcal/d)e

328 (198, 562)

361 (207, 543)

Family characteristics

  Persons per household

4 (3, 4)

 

  Overweight mothersf

66 (31)

 

  Highly educated mothersg

160 (77)

 

  Smoking in the household (yes)

28 (13)

 
  1. BMI Body mass index, SDS Standard Deviation Score, FMI Fat Mass Index, FFMI Fat Free Mass Index.
  2. aCharacteristics are presented prior imputation. The following variables had (n) missing values ATO (58), Tanner (127), Energy (72), physical activity (128), persons per household (121), maternal BMI (5), maternal education (10).
  3. bResults are presented as number and (percentage), median (25th, 75 h percentile) or mean ± Standard Deviation.
  4. cFollow-up was calculated as time between last and first measurement.
  5. dOverweight definitions according to the International Task Force BMI cut-offs for children corresponding to an adult BMI of 25 kg/m2.
  6. eExpressed as energy expenditure in kcal based on the sum of organized and unorganized sport activities.
  7. f≥ 25 kg/m2.
  8. g≥ 12 years of schooling.
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