Early symptoms of thiamine deficiency are easy to miss because they are so nonspecific. They can include fatigue, irritability, sleep disturbances and even abdominal discomfort -- all symptoms that can easily describe a host of other conditions and ailments.onditions known as beriberi and Wernicke-Korsakoff syndrome occur because of thiamine deficiency. Thiamine deficiency is highly avoidable for most, although some are born with a condition known as genetic beriberi in which the body loses its ability to absorb thiamine in foods.