Associations Between Repetitive Negative Thinking and Objective and Subjective Sleep Health in Cognitively Healthy Older Adults

Figures & data

Table 1 Demographic and Clinical Baseline Data (N=127)

Demographic Characteristics	Ratio	Ratio (%)
Sex, Female: Male	80:47	63:37
	Mean (SD)	Range
Age (years)	69.4 (3.8)	64–83
Education (years)	13.0 (3.1)	7–22
Polysomnography
AHI	25.3 (14.8)	0.7–75.5
Sleep duration/TST (hrs)	6.0 (1.08)	3.2–9.2
Short sleep duration (hrs)	4.8 (0.6)	3.2–5.5
Typical sleep duration (hrs)	6.0 (0.3)	5.6–6.5
Long sleep duration (hrs)	7.1 (0.6)	6.5–9.2
Fragmentation/micro-arousals (total nb)	23.2 (9.3)	8–50
WASO (min)	87.0 (47.8)	12–230
Sleep efficiency (%)	77.0 (10.1)	49.6–96.6
Sleep onset latency (min)	20.9 (13.9)	0–88.5
SWS (% of TST)	19.8 (9.6)	0–48.1
REM sleep (% of TST)	18.3 (5.6)	0–33.3
Pittsburgh Sleep Quality Index
Continuous data
Global PSQI score^a	4.9 (3.1)	0–13
Sleep duration (hrs)	7.0 (1.1)	3.5–10
Sleep efficiency (%)	82.8 (12.7)	38.9–103.2
Sleep latency (min)	20.9 (29.3)	1–240
Categorical data
Component 1: Sleep disturbance^a	0.9 (0.6)	0–2
Component 2: Sleep latency^a	0.9 (0.9)	0–3
Component 3: Sleep duration^a	0.5 (0.7)	0–3
Component 4: Sleep efficiency^a	0.8 (1.0)	0–3
Component 5: Sleep fragmentation^a	1.1 (0.4)	0–2
Component 6: Sleep medication^a	0.1 (0.5)	0–3
Component 7: Daytime dysfunction^a	0.4 (0.6)	0–3
St Mary’s Hospital Sleep Questionnaire
Sleep latency (min)^†	44.7 (44.4)	0–330
Sleep duration (hrs)^‡	5.4 (2.3)	0.2–18.6
Sleep efficiency (%)^‡	67.64 (22.8)	49.6–96.6
Penn State Worry Questionnaire	41.8 (11.6)	19–70
Rumination Response Scale: Brooding Subscale	8.0 (2.3)	5–16

Notes: ^†N = 116. ‡N = 112. ^aHigher values indicate worse sleep health on this metric.

Abbreviations: AHI = apnoea-hypopnea index; min = minutes; nb = number; Pittsburgh Sleep Quality Index = PSQI; REM = Rapid Eye Movement Sleep; SD = Standard deviation; SWS = Slow Wave Sleep; WASO = Wake After Sleep Onset; TST = total sleep time.

Table 2 Primary Analysis Results Examining the Relationship Between Worry and Brooding and Sleep Health (N=127)

Variables	Worry			Brooding ^†
	Standardised β/OR	95% CI	P	Standardised β/OR	95% CI	P
Polysomnography
Sleep duration	−0.17	−0.34, 0.00	0.051	−0.09	−0.26, 0.08	0.300
Sleep fragmentation	−0.01	−0.18, 0.15	0.880	0.04	−0.12, 0.21	0.599
Sleep efficiency	−0.32	−0.48, −0.16	<0.001	−0.27	−0.44, −0.10	0.002
Pittsburgh Sleep Quality Index
Sleep disturbance (Component 1)^‡	1.05	1.01, 1.09	0.024	1.14	0.93, 1.40	0.197

Notes: All models are adjusted for age, sex, and sleep apnoea scores. Results in bold are significant at the Bonferroni corrected level of 0.0125. ^‡ Logistic regression (odds ratio). ^†N = 126.

Abbreviations: β, beta coefficient; CI, confidence interval; OR, Odds Ratio.

Figure 1 Associations between RNT and categorical sleep duration: short, typical, and long. (A) Worry and sleep duration, and (B) brooding and sleep duration. Mean and standard deviations shown.

Table 3 Exploratory Analysis Results Examining the Relationship Between Worry and Brooding and Sleep Health (N=127)

Variables		Worry			Brooding ^†
	Standardised β/OR	95% CI	P	Standardised β/OR	95% CI	P
Polysomnography
Objective sleep latency	0.03	−0.15, 0.21	0.767	0.00	−0.18, 0.18	0.970
Proportion of REM sleep	−0.00	−0.17, 0.17	0.979	0.02	−0.16, 0.19	0.859
Proportion of SWS	−0.08	−0.24, 0.09	0.377	−0.08	−0.25, 0.09	0.376
Pittsburgh Sleep Quality Index
PSQI total score (Continuous)	0.23	0.07, 0.40	0.007	0.21	0.04, 0.38	0.018
Subjective sleep duration (Continuous)	−0.08	−0.26 0.10	0.380	−0.04	−0.22, 0.14	0.651
Subjective sleep efficiency (Continuous)	−0.14	−0.32, 0.03	0.110	−0.11	−0.29. 0.06	0.209
Subjective sleep latency (Continuous)	0.05	−0.13, 0.23	0.591	0.18	0.00, 0.35	0.049
Subjective sleep fragmentation^‡ (PSQI component 5)	1.02	0.98, 1.07	0.254	1.07	0.86, 1.34	0.540
Subjective daytime dysfunction^‡ (PSQI component 7)	1.02	0.98, 1.05	0.324	1.30	1.09, 1.54	0.003

Notes: All models are adjusted for age, sex, and sleep apnoea scores. Results in bold are significant at 0.05. ^†N = 126 ^‡ Logistic regression (odds ratio).

Abbreviations: β, beta coefficient; CI, confidence interval; OR, Odds Ratio; REM, Rapid Eye Movement; SWS, Slow Wave Sleep.