Table 4.

Categorical moderators of the effect of improving sleep on composite mental health outcomes.

Variable	Levels	k	g+	95% CI	Q
Significant effect on sleepa	Yes	72	−0.53	−0.69 to −0.38	17.69∗∗∗
	No	31	−0.12	−0.24 to 0.01
Clinical status of MH	Clinical	15	−0.72	−1.14 to −0.30	0.92
	Non-clinical	45	−0.50	−0.68 to −0.31
Comorbidities	Mental health	18	−0.64	−1.00 to −0.29	0.63
	Physical health	20	−0.54	−0.76 to −0.32
	No comorbidities	31	−0.47	−0.72 to −0.23
Follow-up point	Short (<6 months)	61	−0.60	−0.77 to −0.42	10.75∗∗
	Long (≥6 months)	11	−0.18	−0.36 to −0.00
Assessment type	Self-reported	66	−0.54	−0.70 to −0.38	0.62
	Clinician rated	6	−0.44	−0.65 to −0.23
Adjusted data	Adjusted	21	−0.51	−0.77 to −0.26	0.01
	Unadjusted	51	−0.53	−0.72 to −0.35
Recruitment setting	Clinical (MH)	12	−0.52	−1.00 to −0.04	3.72
	Clinical (PH)	14	−0.52	−0.76 to −0.28
	Community	39	−0.39	−0.53 to −0.26
	Mixed	9	−1.12	−1.94 to −0.31
Recruitment method	Voluntary	49	−0.46	−0.58 to −0.34	0.98
	Health professional	7	−0.65	−1.45 to 0.14
	Mixed	8	−0.88	−1.80 to 0.04
Control group	Active control	34	−0.58	−0.87 to −0.30	0.57
	TaU	13	−0.52	−0.75 to −0.29
	Wait-list	25	−0.46	−0.63 to −0.29
Risk of bias	High	31	−0.38	−0.56 to −0.21	0.74
	Low	10	−0.55	−0.91 to −0.20
Intervention type	Acupuncture	7	−1.17	−2.08 to −0.25	2.46
	CBTi	53	−0.44	−0.59 to −0.29
	Exercised basedb	4	−0.52	−0.85 to −0.19
	Pharmacologicalc	2	–	–
	Sleep hygiene onlyc	2	–	–
	Sleep restriction onlyc	1	–	–
	CBT for nightmaresc	1	–	–
	Herbal teac	1	–	–
Intervention format	Group	11	−0.42	−0.92 to 0.08	0.25
	Individual	52	−0.55	−0.73 to −0.38
Intervention delivery	Clinician delivered	43	−0.63	−0.87 to −0.38	4.50∗
	Self-administered	23	−0.34	−0.43 to −0.26
Country of origin	Australia	5	−1.50	−2.39 to −0.60	53.69∗∗∗
	Canada	4	−0.12	−0.40 to 0.17
	China	8	−0.85	−1.59 to −0.11
	Germany	3	−0.49	−0.90 to −0.08
	Korea	4	−0.78	−1.70 to 0.15
	Netherlands	3	−0.16	−0.29 to −0.03
	Sweden	8	−0.28	−0.53 to −0.03
	Taiwan	4	−0.57	−0.61 to −0.52
	UK	9	−0.36	−0.51 to −0.22
	USA	20	−0.50	−0.71 to −0.28
	New Zealandc	2	–	–
	Spainc	1	–	–

Notes: CBTi = cognitive behavioural therapy for insomnia, MH = Mental Health, PH = Physical Health, TaU = treatment as usual, WLC = wait list control.

∗p < 0.05, ∗∗p < 0.01, ∗∗∗p < 0.001.

^aStudies in the ‘No’ moderator category were excluded from the review due to having no significant effect on sleep quality but were included for moderation analysis.

^bThe ‘exercise based’ category combines separate interventions with exercise as a key element, including walking, yoga and Tai Chi.

^cNot included in subgroup analysis due to low number.