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. Author manuscript; available in PMC: 2009 Feb 15.
Published in final edited form as: J Am Geriatr Soc. 2007 Dec 7;56(2):239–246. doi: 10.1111/j.1532-5415.2007.01543.x

Table 1.

Sleep/Wake and Rest/Activity Variables

Control (n = 17)
Light and Placebo (n = 18)
Light and Melatonin (n = 15)
Baseline End of Intervention Baseline End of Intervention Baseline End of Intervention
Variable Mean ± Standard Deviation
Sleep/wake
 Night sleep time, minutes 480 ± 139 512 ± 121 493 ± 105 521 ± 108 459 ± 109 489 ± 105
 Night sleep bout duration, minutes 18 ± 13 16 ± 8 16 ± 7 18 ± 8 14 ± 9 16 ± 10
 Night wake bout duration, minutes 9 ± 7 6 ± 4 7 ± 4 6 ± 4 7 ± 4 6 ± 2
 Number of awakenings at night 34 ± 15 38 ± 12 37 ± 12 34 ± 9 42 ± 16 40 ± 15
 Day sleep time, minutes 274 ± 167 324 ± 171 309 ± 157 334 ± 172 315 ± 129 249 ± 103
 Day sleep bout duration, minutes 7 ± 5 8 ± 4 8 ± 4 8 ± 5 7 ± 3 6 ± 2
 Day wake bout duration, minutes 9 ± 7 12 ± 11 7 ± 4 10 ± 9 8 ± 5 14 ± 8
 Number of day sleep bouts 39 ± 18 43 ± 14 42 ± 16 46 ± 15 46 ± 15 43 ± 16
 Day total activity, counts 99,928 ± 80,025 83,513 ± 67,641 95,905 ± 77,840 78,004 ± 65,672 76,880 ± 43,640 90,598 ± 39,610
 Day sleep time/night sleep time 0.55 ± 0.28 0.63 ± 0.28 0.61 ± 0.24 0.64 ± 0.29 0.70 ± 0.27 0.53 ± 0.22
Rest/activity
 Parametric
  Amplitude 1.21 ± 0.66 1.15 ± 0.64 1.13 ± 0.56 1.09 ± 0.68 0.90 ± 0.64 1.26 ± 0.56
  Acrophase, decimal time 13.76 ± 3.30 14.11 ± 3.95 13.94 ± 1.70 13.37 ± 1.71 14.57 ± 2.61 13.51 ± 1.60
  Goodness of fit of the data to the 24-hour cosine curve (R2) 0.17 ± 0.14 0.16 ± 0.13 0.13 ± 0.10 0.15 ± 0.13 0.11 ± 0.13 0.17 ± 0.12
 Nonparametric
  Interdaily stability 0.53 ± 0.17 0.52 ± 0.15 0.50 ± 0.20 0.49 ± 0.21 0.46 ± 0.16 0.51 ± 0.14
  Intradaily variability 1.19 ± 0.45 1.20 ± 0.34 1.36 ± 0.31 1.36 ± 0.44 1.33 ± 0.38 1.30 ± 0.26
  Activity during 5 least-active hours 44.59 ± 60.25 27.18 ± 33.79 36.33 ± 35.56 31.78 ± 47.48 40.85 ± 37.07 34.82 ± 21.76
  Activity during 10 most-active hours 157.46 ± 118.87 133.41 ± 108.16 149.71 ± 122.02 121.79 ± 102.25 124.22 ± 64.18 139.22 ± 65.01
  Amplitude 112.87 ± 76.73 106.24 ± 86.31 113.37 ± 94.26 90.01 ± 72.75 83.37 ± 51.25 104.70 ± 60.02
  Relative amplitude 0.63 ± 0.20 0.68 ± 0.15 0.60 ± 0.18 0.61 ± 0.21 0.55 ± 0.25 0.61 ± 0.19