Table 2.

Driving performance scores across 3 different lighting conditions.

Driving performance	Overall score (n=591), mean (SD)	Daytime (n=210), mean (SD)	Nighttime (n=181), mean (SD)	Nighttime with glare (n=200), mean (SD)	P value
Average speed (km/h)	73.24 (13.30)	71.55a (8.89)	73.71 (16.33)	74.60 (13.97)	.002
SDSpeeda	0.47 (0.61)	0.42 (0.35)	0.51 (0.92)	0.47 (0.47)	.25
SDLPb (meters)	0.08 (0.06)	0.07 (0.04)	0.08 (0.04)	0.11c,d (0.07)	<.001
Reaction timee (seconds)	1.16 (0.34)f	1.07c,g (0.31)h	1.21 (0.38)i	1.23 (0.29)j	<.001

^aSD of speed.

^bSDLP: SD of lane position.

^cSignificant differences between daytime and nighttime with glare.

^dSignificant differences between nighttime and nighttime with glare.

^eTime between a target box with a stripe appearing above the roadway and the participant pressing a button on the steering wheel for a correct response (horizontal stripe).

^fn=448.

^gSignificant differences between daytime and nighttime.

^hn=182.

ⁱn=138.

^jn=128.