Table 4.

Relationships of academic performance with sleep duration, sleep quality, behavioral and other risk factors

Academic Performance
Variables	β –Coef.	Std. Err.	t	P-value
Sleep quality	−0.012	0.004	−3.03	0.002**
Sleep duration
> 7hours				Ref.
6-7hours	0.0 13	0.0 23	0.57	0.572
5-6 hours	−0.027	0.035	−0.76	0.446
<5 hours	−0.074	0.038	−1.95	0.052
Sex
Female				Ref
Male	0.2 74	0.0 26	10. 63	<0.001**
Class non-attendance
None				Ref
< 1 week	−0.067	0.0 24	−2.77	0.006**
1-2 weeks	−0.094	0.044	−2.15	0.031*
>2 weeks	−0.119	0.060	−2.00	0.045*
Cigarette smoking
No				Ref
Yes	−0.123	0.0 70	−1.76	0.078
Alcohol use
No				Ref
Yes	−0.066	0.0 33	−2.01	0.044*
Khat use
none				Ref
< 1 per week	−0.060	0.0 79	−0.75	0.454
1-2 per week	−0.063	0.054	−1.18	0.238
>=3 per week	0.017	0.063	0.27	0.786
Coffee
No				Ref
Yes	0.0 25	0.0 22	1.12	0.262
Year of study
2nd year				Ref
3rd year	0.0 60	0.0 22	2.76	0.006**
4th year & more	0.192	0.040	4.80	<0.001**

^*P-value≤0.05

^**≤0.01

Note: the model also controlled for stress, depression, and university attended.