Table 2.

Association of demographic and psychological characteristics with sleep duration at baseline in 19,735 young adults

Characteristic	Sleep hours										Total		P value
	0-5		> 5 to < 7		≥ 7 to < 8		≥ 8 to < 9		≥ 9
	n = 363	% (col)	n = 3328	% (col)	n = 6017	% (col)	n = 6291	% (col)	n = 3736	% (col)	n = 19,735	% (col)
Age (years)
17	132	36.36	1378	41.41	2895	48.11	3317	52.73	1916	51.28	9638	48.84
18-19	154	42.42	1379	41.44	2192	36.43	2206	35.07	1390	37.21	7321	37.10
≥ 20	77	21.21	571	17.16	930	15.46	768	12.21	430	11.51	2776	14.07	< 0.0001
Sex
Female	184	50.69	1890	56.79	3339	55.49	3364	53.47	1977	52.92	10754	54.49
Male	179	49.31	1438	43.21	2678	44.51	2927	46.53	1759	47.08	8981	45.51	0.0012
Occupation
1. High school student	123	34.07	1360	41.40	2992	50.34	3398	54.87	1934	52.67	9807	50.41
2. TAFE/Uni student	104	28.81	1049	31.93	1673	28.15	1557	25.14	949	25.84	5332	27.41
3. Employed	95	26.32	729	22.19	1092	18.37	1014	16.37	544	14.81	3474	17.86
4. No work / benefits	39	10.80	147	4.47	186	3.13	224	3.62	245	6.67	841	4.32	< 0.0001
Alcohol harmful drink
No	271	74.66	2731	82.06	5250	87.27	5558	88.39	3315	88.76	17125	86.80
Yes	92	25.34	597	17.94	766	12.73	730	11.61	420	11.24	2605	13.20	< 0.0001
Marijuana use
Never	283	78.39	2672	80.48	5184	86.30	5499	87.56	3311	88.89	16949	86.07
Ever	78	21.61	648	19.52	823	13.70	781	12.44	414	11.11	2744	13.93	< 0.0001
Drugs use
Never	298	82.09	2972	89.55	5586	93.27	5941	94.81	3517	94.59	18314	93.18
Ever	65	17.91	347	10.45	403	6.73	325	5.19	201	5.41	1341	6.82	< 0.0001
Self-harm in past year
No	312	85.95	3103	93.24	5777	96.01	6093	96.85	3607	96.55	18892	95.73
Yes	51	14.05	225	6.76	240	3.99	198	3.15	129	3.45	843	4.27	< 0.0001