The Subjective Sleep Quality and Heart Rate Variability in Hemodialysis Patients

Figures & data

Table 1. Sociodemographic and clinical characteristics of the hemodialysis patients

Variables	Numbers (%)	Mean ± SD
Age (years)		61.70 ± 14.19
BMI (kg/m^2)		24.66 ± 4.12
Female/male	22 (47.83)/24 (52.17)
Smoking habit	0 (0)
Drinking habit	0 (0)
Hypnotics habit	11 (23.91)
Hypertension	29 (63.04)
Diabetes	34 (73.91)
Stroke	3 (6.52)
Hb (g/dL)		10.04 ± 1.25
Hct (%)		30.12 ± 3.57
Platelet count (×10^3/µL)		190.90 ± 61.20
BUN (mg/dL)		75.25 ± 24.7
CRE (mg/dL)		10.08 ± 2.32
Na (meq/L)		136.11 ± 4.03
K (meq/L)		4.38 ± 0.86
Ca (mg/dL)		9 ± 0.96
FPG (mg/dL)		152.78 ± 69.63

Note: Hct, hematocrit; Hb, hemoglobin; BUN, blood urea nitrogen; CRE, creatinine; FPG, fasting plasma glucose.

Table 2. Comparison of heart rate variability between control group, before and after hemodialysis

Characteristics	C	HD-Bas	HD-Post
Number of subjects	50	46	46
Male/female	25/25	22/24	22/24
RR (ms)	852.24 ± 152.69	804.59 ± 155.78	805.7 ± 154.56
VLF (nu)	5.75 ± 0.98	4.22 ± 1.62	4.38 ± 1.44**
LF (nu)	4.71 ± 1.16	2.84 ± 1.5	3.44 ± 1.63**
HF (nu)	4.39 ± 1.07	2.74 ± 1.89	3.32 ± 1.37**
TP (nu)	6.44 ± 0.9	5.05 ± 1.33	5.32 ± 1.21**
Variance (ms^2)	6.61 ± 0.84	5.3 ± 1.3	5.39 ± 1.14**
LF% (ms^2)	44.25 ± 17.62	33.61 ± 20.57	38.89 ± 21.93
HF% (ms^2)	31.91 ± 12.13	34.39 ±16.99	32.46 ± 16.07
LF/HF	0.32 ± 0.78	−0.12 ± 1.09	0.12 ± 1.11

Notes: Data are given as mean ± SD. nu, Normalized units; C, control; HD, hemodialysis; Bas, before start of dialysis; Post, after end of dialysis; RR, R–R intervals; VLF, very-low-frequency power (0.003–0.04 Hz); LF, low-frequency power (0.04–0.15 Hz); HF, high-frequency power (0.15–0.40 Hz); TP, total power (0–0.5 Hz); LF%, LF in normalized units; HF%, HF in normalized units; LF/HF, the ratio of low frequency to high frequency.

* and ** denote values significantly different from C at p < 0.05 and p < 0.01, respectively.

Table 3. Comparison of heart rate variability between non-hypertension and hypertension history, before and after hemodialysis

Characteristics	HD-Bas		HD-Post
	Non-HT	HT	Non-HT	HT
RR (ms)	782.6 ± 136.2	817.4 ± 167.1	829.9 ± 152.7	791.5 ± 156.6
VLF (nu)	3.85 ± 1.81	4.44 ± 1.49	4.17 ± 1.6	4.51 ± 1.35
LF (nu)	2.58 ± 1.42	3 ± 1.55	3.37 ± 1.71	3.49 ± 1.61
HF (nu)	2.69 ± 1.03	2.78 ± 2.27	3.26 ± 0.99	3.36 ± 1.57
TP (nu)	4.7 ± 1.35	5.25 ± 1.29	5.18 ± 1.18	5.39 ± 1.25
Variance (ms^2)	4.92 ± 1.3	5.53 ± 1.27	5.26 ± 1.14	5.47 ± 1.16
LF% (ms^2)	32.99 ± 19.72	33.98 ± 21.38	39.6 ± 25.76	38.48 ± 19.82
HF% (ms^2)	32.79 ± 11.86	35.32 ± 19.53	31.38 ± 14.82	33.1 ± 16.99
LF/HF	−0.11 ± 0.88	−0.12 ± 1.2	0.11 ± 1.2	0.13 ± 1.08

Notes: Data are given as mean ± SD. nu, Normalized units; C, control; HD, hemodialysis; Bas, before start of dialysis; Post, after end of dialysis; HT, hypertension; RR, R–R intervals; VLF, very-low-frequency power (0.003–0.04 Hz); LF, low-frequency power (0.04–0.15 Hz); HF, high-frequency power (0.15–0.40 Hz); TP, total power (0–0.5 Hz); LF%, LF in normalized units; HF%, HF in normalized units; LF/HF, the ratio of low frequency to high frequency.

Table 4. Comparison of heart rate variability between non-diabetes and diabetes history, before and after hemodialysis

Characteristics	HD-Bas		HD-Post
	Non-DM	DM	Non-DM	DM
RR (ms)	825.1 ± 151.9	797.4 ± 158.7	819.3 ± 118.4	800.9 ± 166.8
VLF (nu)	4.88 ± 1.27	3.99 ± 1.68	4.95 ± 1.03	4.18 ± 1.52
LF (nu)	3.8 ± 1.41	2.5 ± 1.4	4.32 ± 1.02	3.14 ± 1.7
HF (nu)	3.54 ± 1.38	2.46 ± 1.98	3.59 ± 0.92	3.23 ± 1.5
TP (nu)	5.69 ± 1.13	4.82 ± 1.33	5.83 ± 0.82	5.14 ± 1.29
Variance (ms^2)	5.78 ± 1.07	5.14 ± 1.35	5.92 ± 0.73	5.21 ± 1.21
LF% (ms^2)	43.22 ± 20.12	30.22 ± 19.91	51.33 ± 18.91	34.5 ± 21.45
HF% (ms^2)	32.38 ± 12.65	35.09 ± 18.4	26.77 ± 13.61	34.47 ± 16.57
LF/HF	0.26 ± 0.85	−0.25 ± 1.14	0.73 ± 0.97	−0.09 ± 1.09

Notes: Data are given as mean ± SD. nu, Normalized units; C, control; HD, hemodialysis; Bas, before start of dialysis; Post, after end of dialysis; DM, diabetes mellitus; RR, R–R intervals; VLF, very-low-frequency power (0.003–0.04 Hz); LF, low-frequency power (0.04–0.15 Hz); HF, high-frequency power (0.15–0.40 Hz); TP, total power (0–0.5 Hz); LF%, LF in normalized units; HF%, HF in normalized units; LF/HF, the ratio of low frequency to high frequency.

*Denotes values significantly different at p < 0.05. Values analyzed with Wilcoxon rank sums test.

Table 5. The global scores of PSQI, AIS, and ESS

Variables	Mean ± SD
PSQI	7.63 ± 3.65
AIS	7.57 ± 4.30
ESS	5.54 ± 4.23

Note: PSQI, Pittsburgh sleep quality index; AIS, Athens insomnia scale; ESS, Epworth sleepiness scale.

Table 6. Comparison of some demographics, laboratory data, and autonomic indexes between good sleepers and bad sleepers by PSQI

Variable	Good sleeper (PSQI ≤ 5)	Poor sleeper (PSQI > 5)	p-Value
Numbers	11 (23.91)	35 (76.09)
PSQI	3.73 ± 1.10	8.86 ± 3.29	<0.0001
BMI (kg/m^2)	26.46 ± 4.34	24.09 ± 3.94	0.1147
Hb (g/dL)	10.63 ± 1.13	9.86 ± 1.25	0.0673
RR (ms) – Bas	718 ± 86.27	831.8 ± 163.53	0.0286
VLF (nu) – Bas	3.81 ± 2	4.35 ± 1.49	0.3882
LF (nu) – Bas	2.14 ± 1.35	3.06 ± 1.49	0.0845
HF (nu) – Bas	1.83 ± 1.21	3.03 ± 1.99	0.0086
TP (nu) – Bas	4.53 ± 1.41	5.21 ± 1.28	0.0584
Variance (ms^2) – Bas	4.67 ± 1.53	5.5 ± 1.18	0.0155
LF% (ms^2) – Bas	35.28 ± 19.25	33.09 ± 21.2	0.6155
HF% (ms^2) – Bas	24.56 ± 11.92	37.47 ± 17.3	0.0286
LF/HF – Bas	0.3 ± 0.93	−0.25 ± 1.11	0.1683
RR (ms) – Post	741.55 ± 115.13	825.86 ± 161.16	0.1075
VLF (nu) – Post	4.49 ± 1.76	4.35 ± 1.36	0.6615
LF (nu) – Post	3.33 ± 2.1	3.48 ± 1.49	0.5113
HF (nu) – Post	2.8 ± 1.74	3.49 ± 1.22	0.0534
TP (nu) – Post	5.24 ± 1.56	5.34 ± 1.11	0.4552
Variance (ms^2) – Post	5.18 ± 1.5	5.46 ± 1.02	0.3882
LF% (ms^2) – Post	44.93 ± 22.56	37 ± 21.71	0.2362
HF% (ms^2) – Post	25.52 ± 13.49	34.64 ± 16.37	0.1255
LF/HF – Post	0.54 ± 1.06	−0.01 ± 1.11	0.1319

Notes: Data are given as mean ± SD or number (%). PSQI, Pittsburgh sleep quality index; Hb, Hemoglobin; RR, R–R intervals; VLF, very-low-frequency power (0.003–0.04 Hz); LF, low-frequency power (0.04–0.15 Hz); HF, high-frequency power (0.15–0.40 Hz); TP, total power (0–0.5 Hz); LF%, LF in normalized units; HF%, HF in normalized units; LF/HF, the ratio of low frequency to high frequency; Bas, before start of dialysis; Post, after end of dialysis.

*Values analyzed with Wilcoxon rank sum test.

Table 7. The relationship between autonomic indexes and mean scores of subjective sleep quality in PSQI

	Very good (0)	Quite good (1)	Quite poor (2)	Very poor (3)	p-Value	Scheffe**
Variance (ms^2) – Bas	3.75 ± 1.18	5.25 ± 1.51	5.8 ± 0.93	4.99 ± 1.11	0.0258	2 > 0
HF (nu) – Post	1.52 ± 0.78	3.33 ± 1.55	3.81 ± 1.17	3.02 ± 0.85	0.0170	2 > 0

Notes: Data are given as mean ± SD or number (%). PSQI, Pittsburgh sleep quality index. Bas, before start of dialysis; Post, after end of dialysis. nu, normalized units.

*Values analyzed with ANOVA.

**Values analyzed with Scheffe's post-hoc test.

Table 8. The relationship between autonomic indexes and mean scores of sleep latency in PSQI

	<15 min (0)	16–30 min (1)	31–60 min (2)	>60 min (3)	p-Value	Scheffe**
Variance (ms^2) – Bas	8.44 ± 0	4.5 ± 1.04	5.15 ± 1.14	5.57 ± 1.29	0.0178	0 > 1
HF (nu) – Post	6.71 ± 0	2.47 ± 0.92	3.39 ± 1.44	3.39 ± 1.21	0.0253	0 > 1
Variance (ms^2) – Post	8.39 ± 0	4.77 ± 1.25	5.3 ± 1.18	5.54 ± 0.84	0.0190	0 > 1

Notes: Data are given as mean ± SD or number (%). Bas, before start of dialysis; Post, after end of dialysis; nu, normalized units.

*Values analyzed with ANOVA.

**Values analyzed with Scheffe's post-hoc test.

Table 9. Comparison of some demographics, laboratory data, and autonomic indexes between non-insomnia and insomnia by AIS

Variable	Non-insomnia (AIS ≤ 5)	Insomnia (AIS > 5)	p-Value
Number	39 (84.78)	7 (15.22)
AIS	4.36 ± 3.23	12.14 ± 2.79	<0.0001
BMI (kg/m^2)	24.22 ± 4.14	27.09 ± 3.24	0.0368
Hb (g/dl)	10.1 ± 1.26	9.74 ± 1.26	0.3749
RR (ms) – Bas	818 ± 163.46	729.86 ± 71.5	0.1225
VLF (nu) – Bas	4.19 ± 1.76	4.39 ± 0.32	0.8785
LF (nu) – Bas	2.82 ± 1.58	2.98 ± 1.05	0.8067
HF (nu) – Bas	2.79 ± 2.01	2.49 ± 1.15	0.3752
TP (nu) – Bas	5.06 ± 1.43	4.99 ± 0.45	0.6246
Variance (ms^2) – Bas	5.34 ± 1.4	5.12 ± 0.46	0.5925
LF% (ms^2) – Bas	33.02 ± 20.54	36.9 ± 22.04	0.7136
HF% (ms^2) – Bas	36.32 ± 16.59	23.59 ± 16.19	0.06
LF/HF – Bas	−0.22 ± 1.1	0.49 ± 0.85	0.105
RR (ms) – Post	816.9 ± 161.46	743.29 ± 93.36	0.2844
VLF (nu) – Post	4.31 ± 1.48	4.79 ± 1.25	0.6464
LF (nu) – Post	3.36 ± 1.57	3.93 ± 2	0.4817
HF (nu) – Post	3.28 ± 1.38	3.59 ± 1.4	0.3589
TP (nu) – Post	5.25 ± 1.22	5.66 ± 1.22	0.3751
Variance (ms^2) – Post	5.37 ± 1.17	5.53 ± 1.03	0.5612
LF% (ms^2) – Post	38.14 ± 21.21	43.08 ± 27.06	0.6909
HF% (ms^2) – Post	33.04 ± 16.13	29.24 ± 16.59	0.6909
LF/HF – Post	0.08 ± 1.09	0.35 ± 1.26	0.5011

Notes: Data are given as mean ± SD or number (%). AIS, Athens insomnia scale; Hb, Hemoglobin; RR, R–R intervals; VLF, very-low-frequency power (0.003–0.04 Hz); LF, low-frequency power (0.04–0.15 Hz); HF, high-frequency power (0.15–0.40 Hz); TP, total power (0–0.5 Hz); LF%, LF in normalized units; HF%, HF in normalized units; LF/HF, the ratio of low frequency to high frequency; Bas, before start of dialysis; Post, after end of dialysis; nu, normalized units.

*Values analyzed with Wilcoxon rank sum test.

Table 10. The relationship between autonomic indexes and mean scores of awakenings during the night in AIS

	No problem (0)	Minor problem (1)	Considerable problem (2)	Serious problem or did not sleep at all (3)	p-Value	Scheffe**
HF (nu) – Bas	1.37 ± 2.59	2.94 ± 1.56	3.66 ± 1.08	2.99 ± 1.41	0.0284	2 > 0

Notes: Data are given as mean ± SD or number (%). AIS, Athens insomnia scale; HF, high-frequency power (0.15–0.40 Hz); Bas, before start of dialysis; nu, normalized units.

*Values analyzed with ANOVA.

**Values analyzed with Scheff's post-hoc test.

Table 11. The relationship between autonomic indexes and mean scores of final awakening in AIS

	Not earlier (0)	A little earlier (1)	Markedly earlier (2)	Much earlier or did not sleep at all (3)	p-Value	Scheffe**
HF (nu) – Bas	4.78 ± 1.33	3.38 ± 1.37	4.07 ± 1.99	4.71 ± 0.57	0.0330	0 > 1

Notes: Data are given as mean ± SD or number (%). AIS, Athens insomnia scale; HF, high-frequency power (0.15–0.40 Hz); Bas, before start of dialysis; nu, normalized units.

*Values analyzed with ANOVA.

**Values analyzed with Scheff's post-hoc test.

Table 12. The relationship between autonomic indexes and mean scores of well-being during the day in AIS

	Normal (0)	Slightly decreased (1)	Markedly decreased (2)	Very decreased (3)	p-Value	Scheffe**
HF% (ms^2) – Bas	37.46 ± 18.5	36.94 ± 15.62	19.1 ± 11.24	–	0.0315	1 > 2

Notes: Data are given as mean ± SD or number (%). AIS, Athens insomnia scale; HF%, HF in normalized units; Bas, before start of dialysis.

*Values analyzed with ANOVA.

**Values analyzed with Scheff's post-hoc test.

Table 13. Comparison of some demographics, laboratory data, and autonomic indexes between non-sleepiness and sleepiness by ESS

Variable	Non-sleepiness (ESS≤9)	Sleepiness (ESS>9)	p-Value
Number	14 (30.43)	32 (69.57)
ESS	4.36 ± 3.23	12.14 ± 2.79	<0.0001
BMI (kg/m^2)	25.67 ± 4.72	24.22 ± 3.82	0.6147
Hb (g/dL)	10.56 ± 1.16	9.82 ± 1.24	0.0356
RR (ms) – Bas	791 ± 144.76	810.53 ± 162.24	0.6587
VLF (nu) – Bas	3.78 ± 1.9	4.42 ± 1.47	0.2618
LF (nu) – Bas	2.27 ± 1.47	3.09 ± 1.46	0.0971
HF (nu) – Bas	2.34 ± 1.59	2.92 ± 2.01	0.1555
TP (nu) – Bas	4.62 ± 1.46	5.23 ± 1.24	0.1357
Variance (ms^2) – Bas	4.91 ± 1.45	5.48 ± 1.22	0.0878
LF% (ms^2) – Bas	29.86 ± 17.51	35.25 ± 21.82	0.5426
HF% (ms^2) – Bas	31.55 ± 15.36	35.63 ± 17.75	0.5038
LF/HF – Bas	−0.08 ± 0.94	−0.13 ± 1.16	0.9334
RR (ms) – Post	815.29 ± 156.4	801.5 ± 156.08	0.8579
VLF (nu) – Post	4.52 ± 1.47	4.32 ± 1.45	0.5115
LF (nu) – Post	3.2 ± 1.66	3.55 ± 1.63	0.39
HF (nu) – Post	3.14 ± 1.64	3.4 ± 1.26	0.4665
TP (nu) – Post	5.29 ± 1.26	5.32 ± 1.22	0.7472
Variance (ms^2) – Post	5.34 ± 1.36	5.41 ± 1.05	0.7654
LF% (ms^2) – Post	35.52 ± 19.27	40.37 ± 23.13	0.6246
HF% (ms^2) – Post	33.16 ± 14.62	32.16 ± 16.89	0.5994
LF/HF – Post	0.06 ± 0.99	0.16 ± 1.17	0.8021

Notes: Data are given as mean ± SD or number (%). ESS, Epworth sleepiness scale; Hb, Hemoglobin; RR, R–R intervals; VLF, very-low-frequency power (0.003–0.04 Hz); LF, low-frequency power (0.04–0.15 Hz); HF, high-frequency power (0.15–0.40 Hz); TP, total power (0–05 Hz); LF%, LF in normalized units; HF%, HF in normalized units; LF/HF, the ratio of low frequency to high frequency; Bas, before start of dialysis; Post, after end of dialysis; nu, normalized units.

*Values analyzed with Wilcoxon rank sum test.