Table 3 Multiple logistic regression analyses to examine the interaction effects of volunteering and insomnia on unfavorable subjective well-being

Age (≥ 75 vs. < 75 years)

0.77 (0.63–0.93)

0.90 (0.75–1.08)

1.25 (0.96–1.61)

0.94 (0.77–1.16)

Sex (male vs. female)

1.17 (0.90–1.52)

1.31 (1.02–1.69)

1.26 (0.89–1.79)

1.37 (1.03–1.80)

Body mass index (kg/m²)

  < 18.5 vs. 18.5–23.9

1.53 (0.96–2.42)

1.23 (0.78–1.95)

1.41 (0.76–2.61)

1.27 (0.78–2.07)

  > 23.9 vs. 18.5–23.9

0.96 (0.79–1.16)

0.93 (0.78–1.12)

0.96 (0.75–1.23)

0.86 (0.70–1.06)

 Disabled vs. 18.5–23.9

1.91 (1.23–2.95)

1.19 (0.77–1.87)

7.16 (3.45–14.88)

2.16 (1.39–3.34)

 Education status (illiterate vs. literate)

1.46 (1.18–1.82)

1.75 (1.41–2.18)

1.81 (1.36–2.40)

0.87 (0.68–1.10)

Marital status

 Single/ divorced/ separated vs. Married

1.61 (0.78–3.30)

1.66 (0.78–3.55)

1.73 (0.71–4.21)

1.05 (0.49–2.29)

 Widowed vs. Married

0.96 (0.78–1.19)

1.27 (1.03–1.55)

0.85 (0.64–1.12)

0.99 (0.79–1.24)

 Living status (alone vs. with others)

1.00 (0.74–1.36)

1.05 (0.79–1.40)

1.31 (0.88–1.93)

1.00 (0.73–1.38)

 Frequency of exercise per week (≥ 3 vs. < 3 / week)

1.21 (1.00–1.45)

1.32 (1.11–1.58)

1.51 (1.19–1.92)

1.12 (0.92–1.36)

Smoking status

 Ex- smoker vs. Non-smoker

1.26 (0.93–1.72)

1.42 (1.06–1.91)

1.06 (0.70–1.61)

0.80 (0.57–1.12)

 Current smoker vs. Non-smoker

0.91 (0.63–1.31)

1.35 (0.96–1.90)

0.90 (0.55–1.48)

0.81 (0.55–1.20)

Drinking status

 Ex- drinker vs. Non-drinker

0.99 (0.65–1.50)

1.00 (0.67–1.51)

1.10 (0.63–1.92)

0.40 (0.24–0.66)

 Current drinker vs. Non-drinker

0.85 (0.64–1.14)

0.75 (0.57–0.99)

0.65 (0.44–0.96)

0.62 (0.45–0.86)

Medical history

 Diabetes mellitus (yes vs. no)

1.51 (1.22–1.86)

1.00 (0.81–1.23)

1.52 (1.15–2.01)

1.20 (0.96–1.51)

 Hypertension (yes vs. no)

1.30 (1.08–1.58)

1.26 (1.04–1.51)

1.11 (0.86–1.43)

0.95 (0.77–1.16)

 Cardiovascular disease (yes vs. no)

1.26 (1.04–1.53)

1.00 (0.83–1.21)

1.48 (1.15–1.91)

0.86 (0.70–1.06)

 Hyperlipidemia (yes vs. no)

1.15 (0.93–1.43)

1.15 (0.93–1.42)

0.95 (0.71–1.26)

0.95 (0.75–1.20)

 Stroke (yes vs. no)

1.15 (0.76–1.76)

1.01 (0.66–1.54)

2.76 (1.53–4.98)

1.14 (0.73–1.77)

 Snore (yes vs. no)

1.55 (0.69–3.49)

0.80 (0.35–1.79)

3.57 (1.24–10.28)

0.54 (0.18–1.64)

Hospital Anxiety Depression Scale

 Depression (≥ 6 vs. < 6)

1.49 (1.08–2.05)

2.29 (1.58–3.30)

1.12 (0.75–1.66)

5.77 (3.99–8.34)

 Anxiety (≥ 3 vs. < 3)

1.78 (1.46–2.16)

2.17 (1.79–2.64)

1.16 (0.90–1.51)

3.24 (2.66–3.96)

 Groningen Activity Restriction Scale (≥ 19 vs. < 19)

2.59 (2.15–3.13)

1.89 (1.57–2.27)

27.98 (21.40–36.58)

1.66 (1.35–2.03)

 Taking hypnotics in the past one month (yes vs no)

1.69 (1.38–2.09)

1.55 (1.26–1.92)

1.34 (1.02–1.76)

1.78 (1.43–2.22)

 Epworth Sleepiness Scale (≥ 11 vs. < 11)

1.14 (0.87–1.50)

0.98 (0.75–1.29)

1.10 (0.78–1.56)

1.95 (1.47–2.60)

Athens Insomnia Scale (≥ 5 vs. < 5)

1.57 (1.25–1.96)

1.46 (1.16–1.84)

1.28 (0.96–1.71)

1.55 (1.22–1.96)

Volunteer (yes vs. no)

0.65 (0.47–0.90)

0.48 (0.35–0.66)

0.67 (0.42–1.06)

1.22 (0.88–1.70)

Athens Insomnia Scale x Volunteer

1.09 (0.52–2.25)

2.26 (1.10–4.65)

1.29 (0.49–3.44)

0.39 (0.18–0.87)