Table 1.

Demographic characteristics of the study population

Characteristics	Total		Suicidal ideation		No suicidal ideation			Suicidal plan		No suicidal plan			Suicide attempt		No suicide attempt
	N	%*	N	%*	N	%*	p Value†	N	%*	N	%*	p Value†	N	%*	N	%*	p Value†
Awakening time (military time)							<0.0001					<0.0001					<0.0001
≤5:00	3048	1.5	829	27.2	2219	72.8		364	11.9	2684	88.1		258	8.2	2790	91.8
6:00	43 906	22.0	8700	19.7	35 206	80.3		2816	6.4	41 090	93.6		1830	4.1	42 076	95.9
7:00	121 261	63.7	20 556	16.8	100 705	83.2		6540	5.3	114 721	94.7		4232	3.4	117 029	96.6
8:00	23 199	12.6	4016	17.3	19 183	82.7		1465	6.3	21 734	93.7		979	4.1	22 220	95.9
≥9:00	228	0.1	48	20.9	180	79.1		19	8.2	209	91.8		13	5.5	215	94.5
Bedtime (military time)							<0.0001					<0.0001					<0.0001
≤21:00	1798	0.8	311	18.1	1487	81.9		141	8.6	1657	91.4		85	5.2	1713	94.8
22:00	9980	4.6	1460	14.9	8520	85.1		603	6.3	9377	93.7		398	4.1	9582	95.9
23:00	33 472	16.4	4766	14.2	28 706	85.8		1667	5.0	31 805	95.0		1024	3.1	32 448	96.9
24:00	56 028	29.2	9082	15.9	46 946	84.1		2948	5.1	53 080	94.9		1956	3.3	54 072	96.7
1:00	49 521	26.6	9006	17.9	40 515	82.1		3096	7.4	37 747	92.6		1763	3.4	47 758	96.6
≥2:00	40 843	22.4	9524	22.9	31 319	77.1		2749	5.4	46 772	94.6		2086	5.0	38 757	95.0
Time in bed (h)							<0.0001					<0.0001					<0.0001
≤4	17 653	9.6	4610	25.6	13 043	74.4		1613	8.8	16 040	91.2		1114	6.1	16 539	93.9
5	34 078	18.3	6992	20.2	27 086	79.8		2104	6.1	31 974	93.9		1331	3.8	32 747	96.2
6	46 513	24.7	8450	17.8	38 063	82.2		2629	5.5	43 884	94.5		1718	3.6	44 795	96.4
7	47 892	24.8	7706	15.9	40 186	84.1		2485	5.1	45 407	94.9		1660	3.4	46 232	96.6
8	32 423	16.3	4595	14.1	27 828	85.9		1635	5.1	30 788	94.9		1025	3.2	31 398	96.8
9	10 984	5.3	1497	13.7	9487	86.3		599	5.4	10 385	94.6		370	3.2	10 614	96.8
≥10	2099	1.0	299	14.8	1800	85.2		139	6.9	1960	93.1		94	5.1	2005	94.9
Grade							<0.0001					<0.0001					<0.0001
13	30 904	15.4	5340	17.6	25 564	82.4		2078	6.9	28 826	93.1		1386	4.5	29 518	95.5
14	31 201	15.8	5864	18.7	25 337	81.3		2229	7.1	28 972	92.9		1508	4.9	29 693	95.1
15	31 992	16.6	5834	18.2	26 158	81.8		2056	6.5	29 936	93.5		1362	4.2	30 630	95.8
16	32 420	17.4	5803	17.6	26 617	82.4		1755	5.3	30 665	94.7		1163	3.5	31 257	96.5
17	32 540	17.3	5924	17.7	26 616	82.3		1695	5.0	30 845	95.0		1050	3.0	31 490	97.0
18	32 585	17.5	5384	16.3	27 201	83.7		1391	4.2	31 194	95.8		843	2.5	31 742	97.5
Gender							<0.0001					<0.0001					<0.0001
Male	95 800	51.8	12 955	13.6	82 845	86.4		4400	4.6	91 400	95.4		2408	2.5	93 392	97.5
Female	95 842	48.2	21 194	22.1	74 648	77.9		6804	7.1	89 038	93.0		4904	5.1	90 938	94.9
Region							0.2686					<0.0001					0.1894
Metropolitan	87 318	44.7	15 686	17.9	71 632	82.1		5130	5.8	82 188	94.2		3257	3.7	84 061	96.3
Urban	81 286	49.0	14 394	17.5	66 892	82.5		4674	5.7	76 612	94.3		3119	3.8	78 167	96.2
Rural	23 038	6.3	4069	17.6	18 969	82.4		1400	6.0	21 638	94.0		936	4.0	22 102	96.0
Economic status							<0.0001										<0.0001
Low	42 507	21.6	10 464	24.4	32 043	75.6						<0.0001	2393	5.5	40 114	94.5
Middle	91 299	47.3	14 643	15.9	76 656	84.1		3496	8.1	39 011	91.9		2949	3.2	88 350	96.8
High	57 836	31.1	9042	15.7	48 794	84.3		4571	4.9	86 728	95.1		1970	3.4	55 866	96.6
Academic performance							<0.0001					<0.0001					<0.0001
Low	71 076	36.9	15 260	21.4	55 816	78.6		5259	7.3	65 817	92.7		3738	5.1	67 338	94.9
Middle	52 533	27.5	8350	15.7	44 183	84.3		2540	4.7	49 993	95.3		1591	2.9	50 942	97.1
High	68 033	35.6	10 539	15.3	57 494	84.7		3405	5.0	64 628	95.0		1983	2.9	66 050	97.1
Disease							<0.0001					<0.0001					<0.0001
Yes	36 232	19.5	7773	21.1	28 459	78.9		2758	7.5	33 474	92.5		1805	4.9	34 427	95.1
No	155 410	80.5	26 376	16.8	129 034	83.2		8446	5.3	146 964	94.7		5507	3.5	149 903	96.5
Alcohol use							<0.0001					<0.0001					<0.0001
Yes	90 979	47.2	20 200	21.9	70 779	78.1		6943	7.5	84 036	92.5		4744	5.1	86 235	94.9
No	100 663	52.8	13 949	13.9	86 714	86.1		4261	4.2	96 402	95.8		2568	2.5	98 095	97.5
Smoking use							<0.0001					<0.0001					<0.0001
Yes	45 203	23.5	11 271	24.3	33 932	75.7		4318	9.3	40 885	90.7		3124	6.7	42 079	93.3
No	146 439	76.5	22 878	15.6	123 561	84.4		6886	4.7	139 553	95.3		4188	2.8	142 251	97.2
Drug use							<0.0001					<0.0001					<0.0001
Yes	1811	0.9	836	45.5	975	54.5		542	29.1	1269	70.9		400	21.1	1411	78.9
No	189 831	99.1	33 313	17.4	156 518	82.6		10 662	5.5	179 169	94.5		6912	3.6	182 919	96.4
Exercise							<0.0001					0.0372					0.0674
No	52 047	27.1	9973	18.9	42 074	81.1		3079	5.8	48 968	94.2		2003	3.8	50 044	96.2
1–4 Times a week	114 725	60.0	20 050	17.4	94 675	82.6		6604	5.7	108 121	94.3		4307	3.7	110 418	96.3
5 Times a week	24 870	12.9	4126	16.6	20 744	83.4		1521	6.1	23 349	93.9		1002	4.0	23 868	96.0
Depressive symptoms							<0.0001					<0.0001					<0.0001
Yes	59 858	30.9	24 511	40.9	35 347	59.1		8495	14.1	51 363	85.9		5775	9.5	54 083	90.5
No	131 784	69.1	9638	7.3	122 146	92.7		2709	2.0	129 075	98.0		1537	1.2	130 247	98.8
Year							<0.0001					<0.0001					0.3321
2011	64 647	33.7	12 381	19.1	52 266	80.9		4047	6.2	60 600	93.8		2551	3.8	62 096	96.2
2012	63 688	33.1	11 431	17.7	52 257	82.3		3754	5.8	59 934	94.2		2329	3.6	61 359	96.4
2013	63 307	33.2	10 337	16.2	52 970	83.8		3403	5.3	59 904	94.7		2432	3.8	60 875	96.2
Total	191 642	100.0	34 149	17.7	157 493	82.3		11 204	5.8	180 438	94.2		7312	3.7	184 330	96.3

*weighted %; †weighted p value.