Sleep deficiency can cause problems with a person’s mental health, physical health, quality of life and safety. The main side effect of sleep deprivation is excessive daytime sleepiness, which can lead to safety hazards because it causes drowsy driving and workplace injuries. Some side effects of lack of sleep include: Irritability; Lack of motivation; Lack of concentration; Anxiety; Fatigue; Restlessness; Lack of coordination; Increased errors; Forgetfulness; High blood pressure; Obesity; Diabetes and Lack of energy.