Table 2 Subgroup analyses of effect of aromatherapy on sleep quality

 Undergoing chemotherapy

3

5

176

164

-0.94

−1.29

−0.58

< 0.01

− 0.95

− 1.18

− 0.72

< 0.01

 Perioperative period

4

4

161

155

− 0.92

− 1.55

− 0.30

< 0.01

− 0.89

− 1.13

− 0.66

< 0.01

 Breast cancer

2

2

128

113

−0.98

−1.57

− 0.40

< 0.01

− 0.99

−1.27

−0.72

< 0.01

 Digestive system cancers

2

2

94

95

−0.58

− 0.98

− 0.18

< 0.01

− 0.60

− 0.90

−0.31

< 0.01

 Mixed types

3

5

157

150

−0.58

− 0.87

− 0.30

< 0.01

−0.58

− 0.81

−0.34

< 0.01

 Placebo

3

4

126

125

−0.64

−0.89

− 0.38

< 0.01

− 0.64

−0.89

− 0.38

< 0.01

 Usual care

7

10

348

334

−0.88

−1.27

−0.49

< 0.01

− 0.86

− 1.02

− 0.70

< 0.01

 Single essential oil

7

11

391

366

−0.94

−1.25

− 0.62

< 0.01

− 0.91

−1.07

− 0.76

< 0.01

 Lavender

5

6

241

216

−1.06

−1.49

−0.63

< 0.01

− 1.05

− 1.25

− 0..85

< 0.01

 others

4

5

150

150

−0.77

−1.22

− 0.31

< 0.01

− 0.72

− 0.96

− 0.48

< 0.01

 Compound essential oil

2

2

61

65

−0.21

−0.57

0.14

0.23

−0.21

−0.57

0.14

0.23

 2-4 drops

5

8

292

268

−0.78

−1.04

−0.51

< 0.01

− 0.77

− 0.95

−0.60

< 0.01

 5-8 drops

3

4

95

101

−1.12

−2.06

0.19

0.02

−1.16

−1.47

−0.84

< 0.01

 1 time

7

10

366

367

−0.86

−1.22

− 0.49

< 0.01

− 0.83

− 0.99

−0.68

< 0.01

  > 1 time

3

4

108

92

−0.66

− 0.94

− 0.37

< 0.01

− 0.66

− 0.94

−0.37

< 0.01

 Sleep latency

5

5

186

196

−0.78

−1.15

− 0.42

< 0.01

− 0.60

− 0.67

−0.52

< 0.01

 Sleep duration

4

4

159

166

−0.17

− 0.58

0.24

0.43

−0.35

− 0.45

− 0.26

< 0.01

 Sleep efficiency

3

3

137

138

−0.16

−0.64

0.33

0.53

−0.47

−0.54

− 0.04

< 0.01

 Sleep disturbance

3

3

99

106

−0.58

−0.80

− 0.36

< 0.01

− 0.58

−0.80

0.36

< 0.01