Sleep onset latency is related with reduced bone mineral density in elderly people with insomnia: a retrospective study

Figures & data

Table 1 Baseline characteristics of study population

	Total sample (n=410)	Female (n=176)	Male (n=234)	P-value
Clinical data
Age (year)	81.6±5.9	80.1±5.7	82.7±5.9	<0.01
BMI (kg/m^2)	23.7±3.7	23.7±3.7	23.7±3.7	0.96
PSQI score
Total	7.2±3.7	7.9±3.6	6.6±3.6	<0.01
Daytime dysfunction	0.7±0.7	0.6±0.7	0.7±0.7	0.77
Sleep duration	0.5±0.9	0.64±1.0	0.4±0.9	<0.01
Sleep onset latency	1.6±1.1	1.8±1.0	1.51±1.1	0.01
Sleep disturbances	1.2±0.6	1.2±0.5	1.3±0.6	0.47
Use of sleep medication	1.1±1.4	1.3±1.4	0.9±1.3	<0.01
Sleep efficiency	0.7±1.11	0.9±1.2	0.50±1.0	<0.01
Subjective sleep quality	1.4±0.6	1.5±0.7	1.3±0.6	0.01
Bone mass status
L2–L4 BMD (g/cm^2)	1.1±0.2	1.0±0.2	1.2±0.2	<0.01
L2–L4 T-score	−0.2±2.0	−1.3±1.6	0.6±1.8	<0.01
FN BMD (g/cm^2)	0.8±0.2	0.7±0.1	0.9±0.2	<0.01
FN T-score	−1.3±1.1	−1.8±1.0	−0.9±1.1	<0.01

Abbreviations: BMI, body mass index; PSQI, Pittsburgh Sleep Quality Index; BMD, bone mineral density.

Table 2 Difference of clinical and PSQI data among different bone mass status

Variable	Bone mass status
	Normal (n=136)	OP (n=192)	OS (n=82)	P-value
Total population
Gender (female, %)	24 (17.6)	90 (46.9)	62 (75.6)	<0.01
Age (year)	81.2±6.4	81.9±5.7	81.6±5.8	0.69
BMI (kg/m^2)	24.5±3.7	23.8±3.6	22.4±3.8a,b	<0.01
Total PSQI	6.9±3.9	7.2±3.6	7.7±3.5	0.24
Daytime dysfunction	0.7±0.7	0.6±0.7	0.7±0.7	0.34
Sleep duration	0.5±0.9	0.5±0.9	0.6±0.9	0.73
Sleep onset latency	1.4±1.10	1.74±1.10c	1.70±1.00	0.03
Sleep disturbances	1.2±0.6	1.2±0.6	1.3±0.6	>0.05
Use of sleep medication	1.0±1.3	1.1±1.4	1.3±1.4	0.15
Sleep efficiency	0.6±1.1	0.7±1.1	0.7±1.1	0.51
Subjective sleep quality	1.4±0.6	1.4±0.6	1.4±0.6	0.92
Female
Age (year)	78.4±4.7	80.1±5.7	80.9±5.9	0.16
BMI (kg/m^2)	25.4±2.3	23.9±3.7	22.8±3.8a	<0.01
Total PSQI	8.2±4.4	7.8±3.4	8.1±3.6	0.92
Daytime dysfunction	0.5±0.6	0.6±0.7	0.7±0.8	0.83
Sleep duration	0.8±1.1	0.6±0.9	0.63±1.0	0.81
Sleep onset latency	1.8±1.2	1.8±1.0	1.8±1.1	0.91
Sleep disturbances	1.3±0.5	1.2±0.6	1.2±0.5	0.94
Use of sleep medication	1.3±1.3	1.2±1.4	1.5±1.4	0.50
Sleep efficiency	1.1±1.4	0.9±1.2	0.9±1.2	0.85
Subjective sleep quality	1.4±0.7	1.4±0.6	1.5±0.7	0.93
Male
Age (year)	81.9±6.5	83.5±5.3	83.7±4.9	0.20
BMI (kg/m^2)	24.3±3.9	23.6±3.5	21.5±3.8a,b	<0.01
Total PSQI	6.6±3.7	6.6±3.6	6.3±2.7	0.99
Daytime dysfunction	0.7±0.7	0.6±0.7	0.8±0.4	0.12
Sleep duration	0.5±0.9	0.4±0.9	0.3±0.6	0.69
Sleep onset latency	1.4±1.1	1.7±1.2	1.5±0.8	0.09
Sleep disturbances	1.2±0.6	1.3±0.5	1.4±0.7	0.72
Use of sleep medication	0.9±1.3	0.9±1.3	0.9±1.3	0.97
Sleep efficiency	0.5±1.1	0.5±1.0	0.4±0.9	0.86
Subjective sleep quality	1.4±0.6	1.3±0.6	1.0±0.3c	0.03

Notes:

a Compared with normal group, P<0.01;

b Compared with OS group, P<0.05;

c Compared with normal group, P<0.05.

Abbreviations: OP, osteoporosis; OS, osteopenia; PSQI, Pittsburgh Sleep Quality Index.

Table 3 Association between bone mass parameters and other clinical characteristics

	R value
	L2–L4 BMD	L2–L4 T-score	FN BMD	FN T-score
Age	0.10*	0.09	−0.09	−0.12*
BMI	0.24**	0.23**	0.20**	0.21**
Total PSQI	−0.13**	−0.11*	−0.14**	−0.13**
Daytime dysfunction	−0.05	−0.05	−0.03	−0.03
Sleep duration	0.00	0.02	−0.01	−0.02
Sleep onset latency	−0.18**	−0.18**	−0.15**	−0.14**
Sleep disturbances	−0.03	−0.02	−0.08	−0.07
Use of sleep medication	−0.10*	−0.09	−0.18**	−0.17**
Sleep efficiency	−0.04	−0.02	0.00	−0.01
Subjective sleep quality	−0.07	−0.05	−0.02	−0.01

Notes:

* P<0.05;

** P<0.01.

Abbreviations: BMD, bone mineral density; BMI, body mass index; FN, femoral neck; PSQI, Pittsburgh Sleep Quality Index.

Table 4 Results of multinomial logistic regressions analysis

	OP condition			OS condition
	OR	95% CI	P-value	OR	95% CI	P-value
Gender (women)	22.12	10.32–47.41	<0.01	5.50	3.07–9.86	<0.01
Age	1.07	1.01–1.13	0.02	1.05	1.00–1.09	0.04
BMI <18.5 kg/m^2	4.38	0.93–20.66	0.06	1.36	0.39–4.79	0.63
18.5≤ BMI <24.0 kg/m^2	2.17	0.73–6.50	0.17	1.18	0.54–2.58	0.67
24.0≤ BMI <28.0 kg/m^2	0.49	0.16–1.56	0.23	0.43	0.20–0.96	0.04
BMI ≥28.0	–	–	–	–	–	–
Total PSQI	0.91	0.79–1.04	0.18	0.90	0.81–1.00	0.06
Sleep onset latency of <15 min	0.44	0.12–1.60	0.21	0.38	0.15–0.96	0.04
Sleep onset latency of 16–30 min	0.79	0.30–2.08	0.63	0.37	0.17–0.79	0.01
Sleep onset latency of 31–60 min	0.91	0.35–2.38	0.85	0.71	0.34–1.50	0.37
Sleep onset latency of >60 min	–	–	–	–	–	–
Use of sleeping medication (not during the past month)	0.69	0.27–1.71	0.42	0.86	0.42–1.75	0.68
Use of sleeping medication (less than once a week)	1.31	0.34–5.00	0.69	0.99	0.32–3.11	0.99
Use of sleeping medication (once or twice a week)	1.49	0.42–5.32	0.54	1.00	0.34–2.93	>0.05
Use of sleeping medication (three or more times a week)	–	–	–	–	–	–

Abbreviations: BMI, body mass index; OP, osteoporosis; OS, osteopenia; PSQI, Pittsburgh Sleep Quality Index.