Being tired at the wheel is an under rated cause of vehicular accidents. Studies conducted by sleep research teams shows that a person who has stayed awake an entire day performs the same behind the wheel as a drunk driver with a blood alcohol content (BAC) of .1g. This makes them many more times likely to be involved in an accident then an alert person. In the United States the NTSB, the National Transportation Safety Board has done several studies showing the correlation between sleepiness and accidents especially where heavy trucks are involved. Of long haul truck drivers involved in road accidents, just about 50% are related to fatigue. Other studies have shown that 17% of all accidents each year (around a million) are related to fatigue and 50% of accidents on busy roads were caused by drowsy drivers.