Table 1 Baseline characteristics of insomnia patients by tertiles of serum sodium levels

Age (yr)

61.5 ± 14.8

63.4 ± 14.2

60.4 ± 16.1

60.4 ± 13.8

0.150

Men (%)

231 (56.1)

93 (63.3)

77 (56.6)

61 (47.3)

0.028

Body mass index (kg/m²)

23.5 ± 2.2

23.3 ± 2.0

23.6 ± 2.3

23.6 ± 2.2

0.431

Systolic blood pressure (mmHg)

124.2 ± 12.1

123.8 ± 11.9

124.7 ± 12.1

124.1 ± 12.5

0.826

Diastolic blood pressure (mmHg)

79.8 ± 7.8

79.9. ± 7.3

80.0 ± 8.0

79.5 ± 8.1

0.906

Serum sodium, (mmol/L)

138.9 ± 3.7

135.0 ± 2.9

139.6 ± 0.9

142.5 ± 1.6

<  0.001

Serum potassium (mmol/L)

4.1 ± 0.5

4.2 ± 0.5

4.2 ± 0.5

4.1 ± 0.5

0.570

Hemoglobin (g/dL)

12.6 ± 2.0

12.2 ± 1.9

12.8 ± 2.0

12.7 ± 2.0

0.012

Calcium (mg/dL)

8.9 ± 0.7

8.7 ± 0.6

9.0 ± 0.6

9.0 ± 0.6

<  0.001

Phosphorus (mg/dL)

3.5 ± 0.8

3.4 ± 0.9

3.6 ± 0.7

3.7 ± 0.7

0.025

Glucose (mg/dL)

129.9 ± 50.2

137.7 ± 59.6

130.9 ± 46.4

120.1 ± 40.1

0.015

Total Protein (g/dL)

6.5 ± 0.8

6.3 ± 0.8

6.6 ± 0.8

6.5 ± 0.7

0.043

Albumin (g/dL)

3.8 ± 0.7

3.5 ± 0.7

4.0 ± 0.7

4.0 ± 0.6

<  0.001

Cholesterol (mg/dL)

165.9 ± 45.2

159.6 ± 52.6

170.9 ± 41.7

171.5 ± 37.4

0.007

Uric acid (mg/dL)

4.6 ± 1.7

4.0 ± 1.9

4.8 ± 1.5

5.0 ± 1.6

<  0.001

eGFR (mL/min/1.73m²)

88.3 ± 24.8

89.0 ± 28.1

88.4 ± 22.4

87.4 ± 22.4

0.787

Follow up duration (month)

49.4 ± 29.0

42.5 ± 29.2

53.8 ± 27.7

52.9 ± 28.9

0.001

Charlson Comorbidity Index (CCI) Score

< 0.001

CCI score 0–2 (%)

161 (39.1)

36 (24.5)

61 (44.9)

64 (49.6)

CCI score 3–4 (%)

145 (35.2)

56 (38.1)

47 (34.6)

42 (32.6)

CCI score ≥ 5 (%)

106 (25.7)

55 (37.4)

28 (20.6)

23 (17.8)

Use of thiazide (%)

32 (7.8)

12 (8.2)

11 (8.1)

9 (7.0)

0.920