These stressors include Anxiety Fatigue Exercise Sleep deprivation Withdrawal of alcohol or certain other central nervous system (CNS) depressant drugs (eg, benzodiazepines, opioids) Certain disorders (eg, hyperthyroidism), when symptomatic Consumption of caffeine or recreational drugs such as cocaine, amphetamines, or phencyclidine Use of certain therapeutic drugs, such as theophylline, beta-adrenergic agonists, corticosteroids, and valproate Pathologic (nonphysiologic) tremor There are many causes (see table Some Causes of Tremor), but the most common are For action (including postural) tremors: Essential tremor For resting tremors: Parkinson disease For intention tremors: Cerebellar dysfunction (eg, due to a stroke, trauma, or multiple sclerosis) Table Drugs (see table Some Causes of Tremor by Type) can cause or aggravate different types of tremor.