Table 1.

Baseline characteristics of participants

CharacteristicSleep restriction (n= 46) Mean (SD)Control (n= 51) Mean (SD)
Age, years55.4 (12.7)51.8 (13.4)
Female, n (%)39 (85)36 (71)
Duration of insomnia, years15 (14)14 (13)
Primary outcomes
Pittsburgh Sleep Quality Index2510.43 (3.08)10.29 (3.02)
Insomnia Severity Index2614.76 (3.85)14.51 (3.36)
Sleep efficiency [sleep diary],a %73.32 (11.80)74.15 (11.05)
Sleep efficiency [actigraphy], %82.68 (4.66)82.37 (4.67)
Secondary outcomes — sleep
Epworth Sleepiness Scale315.17 (3.70)6.45 (3.29)
Flinders Fatigue Scale3212.74 (6.83)12.53 (5.11)
Sleep-onset latency, minutes
  Sleep diary31.50 (23.00)29.55 (22.48)
  Actigraphy16.10 (14.47)14.66 (12.42)
Wake after sleep onset, minutes
  Sleep diary44.82 (28.92)47.84 (30.14)
  Actigraphy47.59 (13.88)51.81 (19.51)
Total sleep time, minutes
  Sleep diary369.59 (65.27)376.93 (61.08)
  Actigraphy415.68 (34.17)418.36 (39.36)
Secondary outcomes — mental health
PHQ-9 depression score334.98 (2.76)5.31 (2.80)
GAD-7 anxiety score343.33 (3.06)3.41 (2.45)
Physiological measures
Systolic blood pressure, mmHg122.24 (13.98)123.88 (13.20)b
Diastolic blood pressure, mmHg75.52 (10.35)75.62 (8.98)b
Heart rate, beats per minute68.91 (9.82)73.29 (10.86)
Body mass index, kg/m225.84 (3.89)25.16 (4.28)

  • ↵a Using data averaged from sleep diary recordings for a 2-week period. Sleep efficiency is calculated as total sleep time/time spent in bed × 100%.

  • ↵b n = 50 due to equipment malfunction. PHQ-9 = Patient Health Questionnaire-9. GAD-7 = Generalised Anxiety Disorders-7.