I have 30 years of experience and specialize in the field of human fatigue with specific knowledge in the areas of driver fatigue, hours of service and shift schedules. I have published on such topics as physiology of sleep deprivation, circadian rhythms, and errors and accidents. I have testified 25 times on topics such as operational aspects of extended hours, human fatigue and alertness levels, and interaction between fatigue and alcohol and other chemical substances.