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. 2007 Oct 15;3(6):613–619.

Table 1.

Demographics and Sleep Data for the Entire Group and by Subgroups

Parameter Subjects
p Valuea
All MSL ≥ 8 MSL < 8
No. 54 35 19
Age, y 30.74 ± 10.39 30.09 ± 10.78 31.95 ± 9.79 0.3454
Men, % 87.04 82.86 94.73 0.4001
BMI, kg/m2 27.95 ± 4.45 27.30 ± 4.87 29.14 ± 3.32 0.1477
ESS score 16.15 ± 4.70 15.37 ± 4.47 17.58 ± 4.89 0.0997
Caffeineb 2.45 ± 2.41 2.71 ± 2.67 1.97 ± 1.8 0.4303
Self-reported naps, no./wk 4.40 ± 3.26 3.99 ± 2.54 5.13 ± 4.25 0.5200
AHI, no./h 2.22 ± 3.44 2.18 ± 3.45 2.31 ± 3.53 0.5622
MSL, min 9.75 ± 4.49 12.30 ± 3.53 5.05 ± 1.51 <0.0001*
Sleep-onset REM periods, no. 0.65 ± 1.07 0.49 ± 1.07 0.95 ± 1.13 0.1012
Average nightly sleep duration, h
    Self-reported 6.13 ± 1.23 6.11 ± 1.36 6.18 ± 0.97 0.9413
    Sleep log-recorded 6.99 ± 0.85 6.94 ± 0.93 7.08 ± 0.70 0.5914
    Actigraphy-measured 5.56 ± 1.50 6.10 ±1.37 4.53 ± 1.37 0.0001*
    Differencec 1.43 ± 1.31 0.84 ± 0.83 2.55 ± 1.41 0.0004*
Sleep duration on PSG lab night, h
    By actigraphy 7.09 ± 1.40 7.17 ± 1.65 6.93 ± 1.83 0.8779
    By PSG 7.35 ± 0.65 7.29 ± 1.36 7.47 ± 0.62 0.1920
Sleep efficiency, %
    Measured by actigraphy
        At home 83.19 ± 14.13 87.36 ± 11.11 75.31 ± 16.08 0.0071*
        In lab 89.62 ± 13.96 91.74 ± 9.66 85.49 ± 19.56 0.5873
    Measured by PSG 91.48 ± 6.29 91.69 ± 6.26 91.10 ± 6.48 0.6969
a

p Value is based on comparison of subgroups with mean sleep latency (MSL) ≥ 8 vs MSL < 8 minutes. Data are presented as mean ± SD unless otherwise indicated. BMI refers to body mass index; AHI, apnea-hypopnea index; REM, rapid eye movement.

b

Cups of coffee or tea or cans of soft drink per day.

c

Difference between sleep log and actigraphy-measured average nightly sleep duration.

*

Statistically significant

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