Table 2 Association of sleep parameters with metabolic syndrome and its components among study participants

Bedtime

After 12:00 am vs. before or on 12:00 am

Crude

0.95 (0.70–1.29)

0.73 (0.61–0.87)

1.06 (0.88–1.27)

0.94 (0.74–1.20)

0.84 (0.69–1.02)

0.98 (0.66–1.47)

Adjusted*

1.16 (0.85–1.59)

0.88 (0.73–1.07)

1.14 (0.94–1.38)

0.98 (0.76–1.27)

0.94 (0.77–1.5)

1.11 (0.74–1.68)

Wake time

After 6 am vs. before or on 6 am

Crude

1.04 (0.75–1.45)

0.88 (0.74–1.06)

0.82 (0.67–0.99)

1.16 (0.86–1.51)

0.89 (0.72–1.09)

1.16 (0.73–1.83)

Adjusted*

1.32 (0.93–1.86)

1.00 (0.81–1.23)

1.08 (0.87–1.33)

0.98 (0.73–1.30)

1.14 (0.92–1.42)

1.55 (0.96–2.49)

Napping

Yes vs. no

Crude

1.02 (0.77–1.35)

0.85 (0.73–0.99)

0.94 (0.79–1.11)

0.91 (0.72–1.13)

1.05 (0.88–1.26)

1.27 (0.88–1.83)

Adjusted*

1.05 (0.79–1.40)

0.91 (0.77–1.09)

0.90 (0.76–1.08)

0.98 (0.78–1.24)

1.05 (0.88–1.26)

1.26 (0.87–1.83)

Night shift work

Yes vs. no

Crude

0.40 (0.16–0.98)

0.45 (0.30–0.69)

2.42 (1.74–3.38)

0.18 (0.07–0.48)

1.30 (0.90–1.88)

0.94 (0.41–2.16)

Adjusted*

0.45 (0.18–1.15)

0.93 (0.59–1.47)

1.29 (0.90–1.83)

0.61 (0.21–1.71)

0.88 (0.60–1.30)

0.63 (0.26–1.50)

Sleep duration per night

Short vs. normal

Crude

0.56 (0.33–0.97)

0.63 (0.48–0.82)

1.01 (0.78–1.32)

0.77 (0.52–1.15)

0.80 (0.60–1.08)

0.80 (0.42–1.52)

Adjusted*

0.75 (0.43–1.31)

0.89 (0.66–1.20)

1.20 (0.90–1.59)

0.76 (0.50–1.17)

0.96 (0.71–1.31)

0.96 (0.50–1.84)

Long vs. Normal

Crude

1.00 (0.73–1.39)

1.04 (0.87–1.25)

0.79 (0.64–0.97)

1.52 (1.19–1.94)

0.94 (0.76–1.16)

0.99 (0.64–1.53)

Adjusted*

0.94 (0.68–1.31)

0.82 (0.67–0.99)

0.97 (0.78–1.21)

1.18 (0.92–1.52)

1.04 (0.84–1.29)

1.09 (0.70–1.71)

Sleep duration per day

< 6 h vs. 8–9 h

Crude

0.94 (0.44–1.98)

0.73 (0.47–1.15)

1.63 (1.07–2.49)

0.42 (0.18–0.97)

0.81 (0.49–1.32)

1.40 (0.59–3.31)

Adjusted*

0.89 (0.41–1.91)

0.79 (0.48–1.31)

1.32 (0.85–2.06)

0.52 (0.22–1.24)

0.69(0.42–1.15)

1.20 (0.50–2.88)

6–7 h vs. 8–9 h

Crude

0.86 (0.91–1.21)

1.00 (0.82–1.21)

1.06 (0.87–1.31)

0.73 (0.54–0.98)

0.92 (0.74–1.14)

1.07 (0.68–1.66)

Adjusted*

0.84 (0.60–1.20)

1.06 (0.86–1.31)

0.94 (0.76–1.17)

0.79(0.58–1.07)

0.84 (0.68–1.05)

0.98 (0.63–1.54)

≥ 10 h vs. 8-9 h

Crude

0.72 (0.50–1.02)

0.90 (0.74–1.09)

0.82 (0.66–1.01)

1.20 (0.93–1.55)

0.74 (0.59–0.92)

0.71 (0.43–1.17)

Adjusted*

0.75 (0.52–1.09)

0.85 (0.69–1.06)

1.03 (0.83–1.29)

0.98 (0.75–1.29)

0.86 (0.68–1.08)

0.81 (0.49–1.35)