Table 3.

Sleep patterns of truck drivers

	%	Mean	SD	Time (min)
Sleep duration
Perceived hours needed for highest function		6 h, 45 min	1.532
Actual hours slept		6 h, 55 min
Workday			1.672
< 7 h	46.5
7–9 h	45.7
> 9 h	7.8	8 h, 16 min
Actual hours slept			2.122
Nonworkday
< 7 h	16.9
7–9 h	54.2
> 9 h	28.9
Number and length of naps
Daily naps		0.53	0.818	1 h, 13 min
Workday		1.59	3.390	1 h. 29 min
Nonworkday		t-Ratio; Prob > t		t-Ratio; Prob > t
		4.33; < 0.0001		0.314; 0.3775
Sleep quality
Time to fall asleep (min)		32.01
Workday		30.03
Nonworkday		t-Ratio; Prob > t
		1.04; 0.1489
Good quality sleep
Workday
Never	9.1
Rarely	30.4
Almost every night	42.6
Every night	17.9
Nonworkday
Never	4.7
Rarely	12.1
Almost every night	37.3
Every night	45.9
Difficulty falling asleep (previous 2 wk)
Never	44.4
Rarely	24.0
Sometimes	21.1
Frequently	7.5
Always	3.0
Waking up during sleep (previous 2 wk)
Never	14.3
Rarely	17.7
Sometimes	28.2
Frequently	15.8
Always	24.0
Waking up too early/Unable to fall back asleep (previous 2 wk)
Never	26.0
Rarely	21.2
Sometimes	27.9
Frequently	13.2
Always	11.7