These brief involuntary lapses into sleep, often lasting just a few seconds, can have devastating consequences behind the wheel, says an ear, nose and throat (ENT) specialist.
Dr Riana Kipiani Abdul Halim said during a microsleep episode, the brain momentarily shifts from wakefulness into a sleep state.
“Even if the eyes remain open, the driver is no longer aware of their surroundings,” she said in an interview.
Microsleep, she said, typically occurs when the brain tries to compensate for fatigue or sleep deprivation.
The ENT surgeon from KPJ Klang Specialist Hospital said long-distance journeys, especially during the festive travel surge, significantly heighten the risk as fatigue builds up over time.
She urged drivers to be alert to warning signs of microsleep, including frequent yawning, heavy eyelids, blurred vision, drifting between lanes, missing exits and difficulty recalling recent stretches of the journey.
“If these symptoms appear, stop immediately and rest,” she said.
She stressed that even a few seconds of inattention can be dangerous, noting that at 110km/h, a three-second microsleep episode could result in nearly 100m of uncontrolled driving.
To reduce risk, Dr Riana advised motorists to get at least seven to eight hours of sleep before travelling, take breaks every two hours or 150km to 200km, share driving duties where possible and take short power naps when needed.
She also advised drivers to avoid travelling during peak sleep hours between 2am and 6am.
She added that disrupted sleep patterns during Ramadan can further increase fatigue, making it even more important for drivers to rest well.
Monotonous highway conditions, combined with extended hours behind the wheel, can reduce alertness and make the brain more prone to drifting into sleep.
Dr Riana said those who are sleep deprived, night drivers, shift workers and individuals taking sedating medication are at higher risk of microsleep.
“Many motorists begin their journeys late at night or in the early hours of the morning to avoid congestion, coinciding with the body’s natural sleep cycle when alertness is lowest.
“Those who travel immediately after breaking fast during Ramadan may also experience drowsiness, as the body diverts energy towards digestion,” she elaborated.
She also highlighted obstructive sleep apnoea (OSA) as a key contributing factor, as the condition, which involves repeated airway collapse during sleep, leads to poor sleep quality and excessive daytime drowsiness.
“Many patients with OSA remain undiagnosed for years, despite experiencing symptoms such as loud snoring, choking during sleep, morning headaches and persistent fatigue.”
From an ENT perspective, she explained that conditions such as nasal obstruction, enlarged tonsils, a large tongue or structural abnormalities of the jaw can contribute to airway blockage.
She added that obesity may also worsen the condition due to fat deposition around the airway.
According to the Malaysian Institute of Road Safety Research (Miros), microsleep, or briefly dozing off while driving, is a major contributor to road accidents in Malaysia, accounting for about 20% of cases each year.
Miros said accident risks rise sharply during festive seasons, with Malaysian Highway Authority projections showing more than two million vehicles on highways during such periods.
On Feb 11, a motorcyclist was killed and five others injured in an accident at the Padang Jambu traffic light intersection in Melaka, after the 35-year-old driver was believed to have experienced microsleep.
