Adrenaline works directly on receptor cells in muscles to speed up the contraction rate of the fibres, ready for fighting or fleeing. High levels of adrenaline can therefore lead to muscles twitching uncontrollably, making us shake.

What causes human shaking?

Many other factors or diseases can also cause tremors, including Parkinson's disease, multiple sclerosis, fatigue after exercise, extreme emotional distress, brain tumors, some prescription drugs, metabolic problems, and alcohol or drug withdrawal.

What does it mean when your body shaking for no reason?

Psychogenic movement disorders

For some people, stress or mental health factors can cause shivering and other involuntary movements. This usually occurs due to a psychogenic movement disorder, which can affect any part of the body.