Sleep disorders are changes in sleeping patterns or habits. Signs and symptoms of a sleep disorder may include excessive daytime drowsiness, irregular breathing, increased movement during sleep, difficulty sleeping and abnormal sleep behaviors. Such a disorder can affect your overall health, safety and quality of life. Luckily, most sleep disorders can be effectively treated by doctors. http://www.mayoclinic.org/diseases-conditions/sleep-disorders/basics/definition/con-20037263