Handshakes are a social convention that has been used for at least 3,000 years, according to historians who found a ninth century B.C. relief showing the kings of Babylonia and Assyria shaking hands.

But if your hands are shaking — that's something else completely.

There are many reasons hands can shake: too much caffeine, lack of sleep, and low blood sugar are all possible causes. Some medications for mental illness, seizures, migraine, neuropathy and asthma, as well as immunosuppressants, are also possible triggers.

But the major cause of shaking hands is called essential tremor, which causes involuntary and rhythmic shaking, most often in the hands, when you perform tasks such as drinking from a glass or tying shoelaces. It is not life-threatening, but can be extremely disruptive to daily life. 

Other disorders that may be related to shaky hands include chronic anxiety, hyperthyroidism, multiple sclerosis, Parkinson's, traumatic brain injury, and stroke.

Sometimes, lifestyle changes — such as consuming less caffeine and alcohol, avoiding over-the-top exercise, stress control, and psychotherapy — can relieve symptoms. But because your medications may be to blame or you may have a more serious undiagnosed illness, it's smart to get checked out by your physician.

For essential tremors and other persistent cases, beta-blockers such as propranolol, anxiety medications, and anti-seizure medications such as primidone are suggested. For multiple sclerosis and Parkinson's, there are specific therapies.

Although not every tremor is curable, many can be improved or resolved, so don't shake it off. Get a firm grip on the cause and treatment.