Table 4.

Subgroups based on the different dosages of trazodone.

Outcomes	Heterogeneity (I2) (%)	MD/SMD	95% CI	Z	P1	P2
Dosage ≥ 100 mg/d
TST9,16,31,33	86	49.48	13.24, 85.72	2.68	0.007	0.40
LPS9,31,33	0	− 39.36	− 40.64, − 38.09	60.57	< 0.00001	< 0.00001
N117,29	51	− 1.04a	− 1.96, − 0.11	2.19	0.03	0.28
N29,31	0	− 0.83a	− 1.45, − 0.21	2.61	0.009	0.02
N39,16,18,31,33	93	2.80a	1.31, 4.28	3.69	0.0002	0.002
REM9,31	86	0.39a	− 0.73, 1.50	0.68	0.49	0.60
Dosage ≤ 50 mg/d
TST15,17,28,29	73	25.62	− 15.90, 67.14	1.21	0.23
LPS17,28,29,32	4	− 9.02	− 12.88, − 5.16	4.58	< 0.00001
N19,15,31,32	56	− 0.44a	− 0.98, 0.10	1.59	0.11
N215,17,29,32	0	− 0.01a	− 0.30, 0.28	0.06	0.95
N315,17,29,32	34	0.33a	− 0.09, 0.75	1.52	0.13
REM15,17,29,32	0	0.08a	− 0.20, 0.36	0.57	0.57

CI confidence interval, LPS latency to onset of persistent sleep, MD mean differences, N1 non-rapid eye movement stage 1, N2 non-rapid eye movement stage 2, N3 non-rapid eye movement stage 3, P¹ variation within the group, P² differences between subgroups, REM rapid eye movement, SMD standardized mean differences, TST total sleep time.

^aSMD.