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Table 1 Characteristics of the 3698 middle-aged birth cohort participants according to the quartiles of bedtime regularity (standard deviations of accelerometer-measured bedtime over seven days)

From: Regularity of bedtime, wake-up time, and time in bed in mid-life: associations with cardiometabolic health markers with adjustment for physical activity and sedentary time

 

Bedtime regularity (hh:mm:ss)

 
 

Q1  ≤ 00:39:52

Q2 00:39:53–00:58:50

Q3 00:58:51–01:29:20

Q4  ≥ 01:29:21

 p-value

n (total = 3698)

925

924

925

924

 

Factors related to sleep and time in bed

Bedtime (hh:mm)

23:02 (00:53)

23:08 (00:58)

23:17 (01:09)

23:57 (01:34)

 < 0.001

Wake-up time (hh:mm)

07:01 (00:59)

07:12 (01:01)

07:17 (01:07)

07:39 (01:25)

 < 0.001

Time in bed (hh:mm)

07:59 (00:51)

08:04 (00:50)

08:00 (01:00)

07:42 (01:09)

 < 0.001

Chronotype (n [%])

 < 0.001

 Morning-type

399 (44.9)

356 (40.5)

353 (40.4)

357 (41.3)

 > 0.05

 Day-type

453 (51)

486 (55.4)

471 (53.9)

432 (49.9)

 > 0.05

 Evening-type

36 (4.1)

36 (4.1)

50 (5.7)

76 (8.8)

 < 0.05

Work schedule (n [%])

    

 < 0.001

 Day work

658 (71.1)

646 (69.9)

626 (67.7)

497 (53.8)

 < 0.05

 Shift work

108 (11.7)

129 (14.0)

137 (14.8)

235 (25.4)

 < 0.05

 Not working/no information available

159 (17.2)

149 (16.1)

162 (17.5)

192 (20.8)

 > 0.05

Sociodemographic and lifestyle factors

Men (n [%])

316 (34.2)

319 (34.6)

374 (40.6)

440 (47.7)

 < 0.001

High education (n [%])

280 (31.8)

266 (30.9)

255 (29.8)

196 (23.0)

 < 0.001

Current smoker (n [%])

93 (10.4)

125 (14.1)

170 (19.5)

232 (26.7)

 < 0.001

Heavy alcohol drinkers* (n [%])

42 (4.5)

60 (6.5)

68 (7.4)

104 (11.3)

 < 0.001

Total PA (MET min/day)

1159.2 (362.2)

1094.4 (300.3)

1054.9 (331.0)

1038.9 (333.5)

 < 0.001

Sedentary time (min)

566.5 (93.8)

571.0 (85.7)

581.9 (87.7)

588.6 (89.7)

 < 0.001

Cardiometabolic health markers

WC (cm)

88.3 (12.6)

89.7 (13.2)

91.5 (13.7)

93.4 (13.9)

 < 0.001

 Men

95.1 (10.6)

96.0 (11.6)

97.5 (12.6)

98.6 (12.7)

0.006

 Women

84.8 (12.2)

86.3 (12.8)

87.4 (13.0)

88.6 (13.3)

 < 0.001

BMI (kg/m2)

26.0 (4.7)

26.4 (4.8)

27.0 (5)

27.2 (5)

 < 0.001

SBP (mmHg)

123.8 (15.7)

124.1 (15.3)

124.8 (15.3)

126.3 (16.2)

0.044

DBP (mmHg)

83.5 (10.3)

83.7 (10.9)

84.6 (10.1)

85.6 (10.7)

0.001

Body fat (%)

28.6 (9.0)

29.2 (9.2)

29.6 (9.5)

29.2 (9.6)

0.203

Fat mass (kg)

21.7 (9.9)

22.7 (10.7)

23.8 (11.3)

23.9 (11.3)

 < 0.001

Visceral fat area (cm2)

98.8 (39.1)

102.6 (40.9)

107.7 (43.2)

108.7 (42.9)

 < 0.001

Fasting insulin (pmol/L)

8.98 (6.08)

9.38 (9.13)

9.62 (6.5)

10.45 (9.94)

0.002

2-h insulin (pmol/L)

58.45 (61.78)

58.62 (50.51)

61.66 (60.51)

64.77 (62.21)

0.103

Fasting glucose (mmol/L)

5.39 (0.65)

5.42 (0.65)

5.51 (0.8)

5.58 (0.88)

 < 0.001

2-h glucose (mmol/L)

5.79 (1.58)

5.68 (1.56)

5.89 (1.64)

6.00 (1.86)

0.001

Triglycerides (mmol/L)

1.11 (0.6)

1.16 (0.65)

1.26 (0.7)

1.32 (0.83)

 < 0.001

Total HDL cholesterol ratio

3.48 (0.98)

3.52 (1)

3.63 (1.04)

3.69 (1.06)

 < 0.001

LDL/HDL cholesterol ratio

2.26 (0.89)

2.30 (0.91)

2.40 (0.94)

2.44 (0.96)

 < 0.001

  1. Quartiles were defined by three cut points that divided the participants into four equally sized groups based on the standard deviations of bedtimes over seven days. Values are mean (standard deviation) unless otherwise stated. Numbers do not match owing to missing values
  2. PA physical activity; SBP systolic blood pressure; DBP diastolic blood pressure; BMI body mass index; and WC waist circumference
  3. *Heavy alcohol drinkers: men ≥ 40 g/day; women ≥ 20 g/day
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Journal of Activity, Sedentary and Sleep Behaviors

ISSN: 2731-4391

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