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Table 3 Sleep architecture and descriptive information for the testing sample

From: Using heart rate profiles during sleep as a biomarker of depression

Variable Control [x̅ ± SD]b MDD [x̅ ± SD]b U/χ2 p
n 87 87
Sex Distribution (%female) 55.2 58.6 .211 .646
Age (years) 43.3 ± 11.3 43.6 ± 10.5 3744.0 .903
AHI 1.7 ± 2.8 3.3 ± 5.0 2769.5 .002
BMI (kg/m2) 29.6 ± 6.8
BDI II Score 24.6 ± 9.0
Recording Time Before Sleep (min) 21.6 ± 15.0 40.2 ± 28.3 1882.5 .000
Recording Time After Sleep (min) 9.5 ± 28.9 4.6 ± 8.2 3398.5 .295
Total Recording Duration (min) 468.4 ± 35.6 474.2 ± 55.4 3550.5 .563
Total Sleep Time [TST (min)] 386.2 ± 43.8 355.6 ± 76.4 2891.0 .007
Sleep Efficiency (%) 87.7 ± 7.3 82.9 ± 14.3 3305.0 .149
Sleep Onset Latency (min) 13.6 ± 13.0 20.3 ± 18.7 2782.5 .003
REM Latency (min)a 98.6 ± 48.3 190.9 ± 106.6 1363.5 <.001
WASO (min) 55.1 ± 32.4 72.9 ± 62.2 3451.5 .316
N1 (min) 32.8 ± 18.8 66.4 ± 37.4 1617.5 <.001
N2 (min) 223.1 ± 47.9 207.3 ± 63.4 3151.0 .057
N3 (min) 54.7 ± 39.1 34.8 ± 33.7 2595.0 <.001
REM (min) 75.7 ± 25.5 47.1 ± 32.9 1788.0 <.001
N1 (% of TST) 8.7 ± 5.3 19.5 ± 11.5 1441.0 <.001
N2 (% of TST) 57.7 ± 10.5 58.0 ± 11.5 3760.0 .941
N3 (% of TST) 14.2 ± 10.1 9.7 ± 8.6 2758.0 .002
REM (% of TST) 19.4 ± 5.7 12.9 ± 9.0 1780.0 <.001
  1. aEight individuals from the depression group had no REM sleep bDespite the use of a non-parametric test, the mean and standard deviation is reported for better clarity
  2. AHI Apnea-Hypopnea Index, BMI Body Mass Index, BDI Beck Depression Inventory, REM Rapid eye movement, WASO Wake after sleep-onset, N1 Non-REM 1, N2 Non-REM 2, N3 Non-REM 3