Since less people drive at night and there are fewer crash fatalities at this time for non-alcohol-related traffic fatalities, but alcohol related fatalities are the opposite. Alcohol related fatalities increase at night and this is pronounced for both weekdays and weekends.

Alcohol Involvement in Fatal Crashes Increases at Night

Alcohol-related traffic fatalities are involved in more than half of all nighttime crash fatalities, even though between 10 pm and 1 am less than 8% of drivers are legally intoxicated. On weekends, the portion of all traffic fatalities involving alcohol increases during both day and night relative to alcohol-related fatalities during the week. Alcohol-Related accidents had at least one driver or nonoccupant with a blood alcohol level of at least 0.01 gm/ 100 ml. (Constructed from data in NHTSA Report 809104: http://www-nrd.nhtsa.dot.gov/CATS/listpublications.aspx?Id=C&ShowBy=DocType) ©2008 NBEP
On weekend nights alcohol related crash fatalities outnumber those that are non-alcohol-related. The relative risk is over 5 for drunk drivers being involved in a crash between 8 p.m. and 4 a.m. on weekend nights This indicates that nighttime is a much greater time of risk or alcohol-related fatalities.

Dangerous Time for Drivers: Weekend Nights

Drinking drivers have 5 – 10 times the risk of being involved in fatal crashes on weekend nights between 8 pm and 5 am as do sober drivers.Drinking drivers are not necessarily legally intoxicated (blood alcohol can be below 0.08 g /100 ml) to be included in this risk. (Constructed from data in Levitt, S.D. and Porter, J. et al. J Political Economy 109: 1198-1237, 2001) ©2008 NBEP