Table 3.

Results of two-sample Mendelian randomization [MR] analyses examining causal relationships between four sleep phenotypes (insomnia symptoms, sleep duration, short sleepers, and long sleepers), and PTSD

Mendelian randomization*					Heterogeneity test†			Pleiotropy test‡
Method	nSNP	Beta	SE	P value	Q	Q df	Q p val	Egger Int.	SE	p value
Insomnia symptoms (Lane et al. [19])
MR Egger	38	−0.563	0.986	0.571	24.732	36	0.922	0.011	0.010	0.280
Weighted median	38	0.372	0.403	0.356	—	—	—
Inverse variance weighted	38	0.471	0.288	0.102	25.937	37	0.914
Simple mode	38	0.385	0.838	0.648	—	—	—
Weighted mode	38	0.036	0.688	0.958	—	—	—
Sleep duration (Dashti et al. [42]
MR Egger	70	−0.639	0.555	0.254	86.188	68	0.067	0.011	0.009	0.240
Weighted median	70	−0.136	0.214	0.525	—	—	—
Inverse variance weighted	70	−0.006	0.153	0.966	87.967	69	0.062
Simple mode	70	0.236	0.482	0.626	—	—	—
Weighted mode	70	−0.136	0.363	0.708	—	—	—
Short sleepers (Dashti et al. [42])
MR Egger	24	4.340	2.917	0.151	28.138	22	0.171	−0.025	0.020	0.224
Weighted median	24	0.293	0.796	0.713	—	—	—
Inverse variance weighted	24	0.771	0.635	0.225	30.144	23	0.145
Simple mode	24	−0.551	1.457	0.709	—	—	—
Weighted mode	24	−0.218	1.347	0.873	—	—	—
Long sleepers (Dashti et al. 2019)
MR Egger	6	−1.331	5.092	0.807	1.619	4	0.805	0.009	0.029	0.772
Weighted median	6	0.160	1.852	0.931	—	—	—
Inverse variance weighted	6	0.178	1.521	0.907	1.716	5	0.887
Simple mode	6	0.454	2.594	0.868	—	—	—
Weighted mode	6	0.076	2.721	0.979	—	—	—

Int., intercept; MR, Mendelian randomization; PTSD, posttraumatic stress disorder; SE, standard error; SNP, single nucleotide polymorphism.

*Mendelian randomization was conducted utilizing the TwoSampleMR package in R.

^†Heterogeneity tests were conducted on the MR Egger and inverse variance weighted results within the TwoSampleMR package.

^‡Horizontal directional pleiotropy was tested using the TwoSampleMR package.