London - Many of us may have experienced moments when bits of our bodies shake or twitch - particularly if we’re feeling tired, angry or had too much coffee or alcohol.
But in some cases, there may be an underlying medical reason.
Here, the experts discuss common causes of shakes and twitches, and what to do about them.
Hold a piece of paper on an outstretched palm - the gentle shaking of the paper is a sign of common, but harmless, physiological tremor, says Dr Raj Kapoor, a consultant neurologist at the National Hospital for Neurology and Neurosurgery in London.
We all have it, though it can be exaggerated by stress or sleep deprivation, as this causes extra adrenaline.
Shaky hands usually runs in families. It may also be triggered by the use of asthma inhalers, though doctors are unclear why - it’s possible the drugs act as stimulants, says Dr Nick Silver, a consultant neurologist at The Walton Centre in Liverpool.
There’s no treatment, but these tremors aren’t harmful or a sign of anything serious. Cutting down on caffeine can help because this acts as a stimulant.
In some cases, though, medication such as beta blockers can help - in rare cases, neurosurgery is used to remove the thalamus, a tiny area of the brain that causes tremor.
Unlike the fine shaking of the hands, this is noticeable when the arms are outstretched, perhaps when carrying a cup and saucer or holding a newspaper.
However, the shaking stops when the whole arm is at rest.
Known as essential tremor, it tends to affect people over the age of 40 and lasts throughout life.
It is generally caused by faulty messages from the area of the brain that control muscles throughout the body or in particular areas, such as the hands.
A single alcoholic drink can help suppress essential tremor because alcohol acts as a sedative on the nervous system, calming down nerve signals, says Dr Simon Shields, consultant neurologist at Norfolk and Norwich University Hospitals NHS Foundation Trust.
The condition isn’t curable, but if it is troublesome, symptoms can be managed with medication such as beta blockers - the stress hormone adrenaline makes tremors worse, and beta blockers halt the action of adrenaline.
Spasmodic jerks of the legs -particularly when resting or sleeping - can be a symptom of a condition known as periodic limb movement, which causes uncomfortable sensations in the legs, leading to recurrent movements.
The jerks caused by periodic limb movement tend to be repetitive and rhythmic, perhaps happening every 20 to 40 seconds for anything from a few minutes to several hours throughout the night.
Sufferers may wake up or partially rouse repeatedly at night without being aware of it - they may well have better dream recall as a result. This is because the condition may prevent normal sleep patterns and deep sleep - dreams happen after light sleep.
Dr Silver says that stopping all caffeine and avoiding painkillers can help the disorder in 60 percent of cases, though it is not known why.
One cause is low iron levels because this has an effect on areas of the brain involved in control of movement. So if it persists, ask your GP for a blood test.
Flickering twitch on one side of the face
This may be a hemifacial spasm, says Dr Kapoor.
It’s usually caused by a spontaneous irritation of the facial nerve, perhaps triggered by a blood vessel pressing on the nerve.
It can also happen to people who have had Bell’s palsy - a condition that causes temporary weakness or paralysis of the muscles in one side of the face. Symptoms can get worse when you’re feeling tired or under stress as the muscles may be fatigued.
It’s not harmful, says Dr Shields, though trying to relax and avoid stress can help.
Complementary therapies such as meditation and hypnotherapy may help, too. Patients can also have Botox injections to the face to paralyse nerves temporarily.
Occasionally, people opt for an operation to move a blood vessel away from the facial nerve.
Shaking all over
This is likely to be a sign of low blood sugar, says Dr Shields. It can occur if you go without food or are on a diet.
The shakes are caused by the body pumping out adrenalin to compensate for lack of sugar. Other symptoms include feeling clammy or sweaty. The problem is quickly resolved by eating.
Usually the cause is simply tiredness or eye strain brought on by muscle fatigue, says Andrew Lotery, professor of ophthalmology at the University of Southampton. These spasms can occur on and off for a few days.
Glasses wearers should check their prescription is up to date, as this could be the reason the eyes are working hard. It could also possibly be caused by looking at a screen for too long.
Flickering also happens in people with chronic migraine and often improves on stopping caffeine and taking painkillers.
Sometimes, twitches can be more frequent because of temporary irritation such as scratches to the surface of the eye (cornea) or the membranes lining the eyelids (conjunctiva).
Another condition, blepharospasm, affects the muscles around the eyes, causing an involuntary closing and spasms of the eye. It typically affects people aged 50 to 70. This is treatable with Botox injections around the eye to paralyse the muscles.
Twisting of the head and neck
Brought on by muscle spasms, this is caused by a condition called spasmodic torticollis - also known as cervical dystonia.
It is often caused by sleeping in an awkward position or an injury to the neck muscles.
It can be genetic or due to problems with the brain’s control of posture. Sufferers may find their head is turning to the side involuntarily, when trying to read or write, for example.
Trying to stop this happening can cause shaking and tremors of the head.
Spasmodic torticollis tends to develop in middle age and may even cause spasms of the muscles controlling the eyelids (blepharospasm) and the vocal cords (spasmodic dysphonia).
Botox injections can be effective because they temporarily paralyse the muscle, says Dr Silver. These need to be repeated every three to four months.
Sometimes putting a finger on the chin or face, known as geste antagoniste, can relieve the problem, though it’s not known how.
Shaking after serious exercise
Known as fasciculation, it tends to affect the arms, which will shake for ten minutes after finishing exercise due to fatigue to the muscle fibres.
Some people find bench presses, pull-ups or press-ups (so-called resistance training) can trigger muscle twitching, says Shropshire GP Dr Roger Henderson.
He says the cause of muscle twitching during or after exercise is not clear, but one definite factor is lactic acid, a waste product that builds up in the muscles during exercise, causing them to twitch sporadically when at rest.
The twitching should stop after exercising.
Dr Henderson suggests allowing at least 48 hours between resistance workouts of the same body part so you vary your training routine and the same muscles are not being worked every day.
Mild tremor in one hand
This could be a sign of Parkinson’s disease, a neurological disorder caused by low levels of the brain chemical dopamine.
Low dopamine leads to loss of fine control of movements. It often starts with a mild tremor or shakiness in one hand that is noticeable when sitting still and the arm is supported.
The condition can produce other problems including arms not swinging properly, and sluggish speech and movement.
As the condition starts by affecting the centre of the brain that controls sleep, sense of smell and bowel movement, early symptoms can include constipation, kicking out in sleep and long-term loss of sense of smell.
Hand tremors can also be a sign of ataxia, a condition associated with multiple sclerosis.
Shaking happens when you reach for objects - there is sometimes a wild, uncontrollable tremor of the arm.
Other symptoms are slurred speech and an unsteady gait. - Daily Mail