Hand shaking can be caused by essential tremors or Parkinson's disease, according to Washington University Physicians. Trembling may also be caused by caffeine consumption, stress, anger, cigarette use and fatigue. Alcoholics are likely to experience various tremors when they withdraw from the substance, as are drug users.
Differences in the timing of tremors can indicate the cause of a person's trembling, notes Washington University Physicians. For example, Parkinson's disease commonly causes shaking when a person is not engaging any motor skills. Alternatively, essential tremors are exacerbated by a person's movements and seemingly disappear when the individual is at rest.
Hand shaking sometimes occurs as a result of extreme anxiety, states Calm Clinic. The body is designed to exhibit a fight or flight response during emergencies, which releases adrenaline into the bloodstream. This helps people to make fast decisions and gives them the energy to run away or deal with a threat directly. Under normal conditions, this reaction is healthy and subsides after a few minutes. However, people with extreme anxiety are almost in a perpetual state of fight or flight, and they lack the ability to control the release of adrenaline in their bodies. This can cause unwanted chronic shaking in the hands and other areas of the body.