Skip to main content
Hamburger Menu Close



Excessive blinking, facial twitching, leg shaking, involuntary swearing: What causes such behaviours?

While habitual leg shaking could be a way to work off nervous energy, tics can instead be triggered by anxiety. CNA Lifestyle finds out more from health experts.

Excessive blinking, facial twitching, leg shaking, involuntary swearing: What causes such behaviours?

Tics can begin in childhood and when there are multiple motor tics accompanied by one or more vocal tics, it could be Tourette syndrome. (Photos: iStock/Mack15)

Here’s a question: Are you bouncing your leg (or legs) up and down while reading this? You’ve probably been told before to stop as it is unbecoming, distracting to others (you’re shaking the table!) and for those with a proclivity for superstitions, you’re jolting luck and fortune away.

The leg shaking habit may be borne out of boredom or anxiety, and “is typically not caused by an underlying medical condition”, said Dr Xu Zheyu, a senior consultant with the National Neuroscience Institute’s (NNI) Department of Neurology.

Having said that, Dr Xu noted that there are medical conditions that may induce some lower limb action, such as hyperthyroidism and Parkinson's disease. However, the nature of the movement is quite different to the habitual leg shaking.

For example, in hyperthyroidism, the shaking or tremors are experienced throughout the body and more so in the arms and hands – and not just the legs, she said. Patients with Parkinson’s disease may also experience foot or leg tremors but again, the movement is quite different as it is more subtle and rhythmic.

Are you shaking your leg right now? (Photo: iStock/miodrag ignjatovic)

“Some patients may experience restlessness and jerking of the legs at night. This could be due to restless leg syndrome and may require attention if there is significant fatigue in the daytime,” said Dr Xu.

Otherwise, there is no need to see a doctor for habitual leg shaking, she added.


Tics, on the other hand, are a completely different matter and are involuntary. “Tics are stereotypic repetitive movements (motor tics) or sounds (vocal tics) that interrupt normal muscle activity or speech,” said Dr Shermyn Neo, a consultant with the NNI’s Department of Neurology.

While habitual leg shaking could be a way to work off nervous energy, tics can instead be triggered by anxiety. And it doesn’t only concern the legs. In some individuals, the repetitive movements can manifest as “abnormal, involuntary facial movements known as facial tics”, said Dr Mohammad Tauqeer Ahmad, a neurologist with Gleneagles Hospital.

Added Dr Neo: “Motor tics can also involve various body parts, including the neck, limb and trunk muscles”.

Furthermore, tics can be classified as “simple” (excessive blinking, shrugging or grunting) or “complex” (grimacing or the tendency to use obscene words), explained Dr Neo. “When there are multiple motor tics accompanied by one or more vocal tics, a diagnosis of Tourette syndrome (TS) may be made.”

It is a situation that Billie Eilish, 20, lives with. The singer was diagnosed with TS when she was 11 and has mentioned that the tics are “very exhausting”.

The award-winning artiste told David Letterman on the Netflix show, My Next Guest Needs No Introduction, that the tics abate when she's performing. And while some specific tics have disappeared over time, others still occur regularly.

"I never don't tic at all because the main tics that I do constantly, all day long, are like, I wiggle my ear back and forth and raise my eyebrow and click my jaw ... and flex my arm here and flex this arm, flex these muscles," she said.

"These are things you would never notice if you're just having a conversation with me, but for me, they're very exhausting."


In most cases, such as Eilish's, the primary tics begin in childhood below age 18, said Dr Neo. And males are about four times more likely to be affected by TS than females, she said.

“There are no estimated figures of patients with tics or TS in Singapore, possibly due to cultural differences in seeking medical care. But the global prevalence ranges from 0.4 per cent to 3.8 per cent."

Typically, the tics tend to start with eye blinks at around the ages of five to six and may progress to involve the rest of the face and neck. The tics generally peak in severity at around age 10 and by age 16, “more than half of TS patients may have minimal or mild tics”, she said.

Facial tics also occur mainly in males and show up between the ages of six and 12, said Dr Tauqeer of this uncommon condition in Singapore. They, too, tend to disappear on their own.

(Photo: iStock/primeimages)

As for tics that crop up in adulthood, they are usually reprisals of childhood-onset tics, said Dr Neo. But if there isn’t a childhood history of tics, it is important to look for secondary causes, she said. The patient may be on certain medications that have brought on the tics or has developed a neurological disorder.

For instance, hemifacial spasm, caused by an irritated facial nerve, can result in involuntary facial movements that mimic tics. “It can present as the twitching of half the face due to involuntary contractions of muscles around the eyes and mouth,” said Dr Neo.

However, the exact cause of tics is unclear. “Studies have demonstrated differences in brain volumes and brain network connections in patients with tics compared to those without,” said Dr Neo.

There may also be a genetic link, she said: Multiple genes that have “small effects” have been demonstrated, and up to 50 per cent of TS patients have a family history of tics. Studies on twins have also suggested a genetic predisposition.


Not all tics need to be medically treated. “An indication to treat a tic disorder is when it interferes significantly with daily life,” said Dr Neo.

Explained Dr Tauqeer: “The majority of the time, the tics are precipitated under stressful situations. So up to an extent, it is not wrong to say they can be mitigated by certain destressing techniques. Many patients may not need medication. Rather, the tics will improve on their own with age”.

Dr Neo agreed that tics usually occur and “worsen under conditions of stress, excitement or fatigue”. And like in Eilish's situation, the tics "may decrease with distraction while the patient is concentrating on mental or physical tasks”.

(Photo: iStock/Tirachard)

But even if you are able to cope with the tics, you should get yourself examined by a doctor if you haven’t yet. “What is important is that we must investigate to find out any structural causes through scans, and functional causes through electrophysiological testing,” said Dr Tauqeer.

It is also to rule out “overlapping medical conditions like obsessive-compulsive behaviour, attention deficit hyperactivity disorder, or any behavioural or learning disabilities”, said Dr Neo, which a significant proportion of TS sufferers have. “While most tics are benign, some motor tics can be harmful, with patients exhibiting self-injurious behaviour.”

The mainstay of treatment includes education, counselling, physiotherapy, medications to control symptoms and local botox injections, said Dr Tauqeer. Cognitive behaviour therapy may also be accessed by patients through self-help websites such as, said Dr Neo.

In some cases, deep brain stimulation may be used, said Dr Tauqeer, where electrodes are implanted in certain areas of the brain to produce electrical pulses and regulate abnormal impulses.

Patients can also seek support from Tourette Syndrome Singapore or SPD, a charity that helps individuals with disabilities and also raises awareness of and supports those with tic disorders in Singapore.

Source: CNA/bk