Jet lag may appear to be a temporary inconvenience for most travellers, but in certain cases, it can give rise to more serious complications—especially when ignored, repeated frequently, or poorly managed. While jet lag typically resolves within a few days as the body adapts to a new time zone, its lingering effects can impair health, productivity, and overall well-being. Understanding these complications is vital, particularly for individuals who travel regularly for business, sport, or international assignments.
Complications range from short-term problems like lowered alertness and poor performance to long-term risks such as mental health issues, sleep disorders, and even heart problems. By identifying and dealing with these risks, travellers can plan better trips and lessen the effects of ongoing body clock disruption.
Cognitive Impairment and Reduced Performance
One of the first and most obvious effects of jet lag is reduced brain function. Travellers often notice:
- Slower reaction times
- Poor focus and memory
- Mental tiredness and confusion
- Trouble understanding information
These problems can hurt work performance, slow decision-making, and increase safety risks. This is especially true in jobs needing strong focus, like flying planes, healthcare, or emergency work. Even daily tasks such as driving can become dangerous when attention and reflexes drop. Research shows jet lag can lower performance to the same level as being very tired or drunk, especially in the first one to two days after arrival.
Mood Disturbances and Mental Health Impacts
Jet lag often causes mood swings, including irritability, anxiety, and feeling down. These mood changes usually last a short time. However, for some people—especially those with mental health problems—jet lag can make things worse, including:
- Depression
- General anxiety disorder
- Seasonal affective disorder (SAD)
Changes in melatonin and cortisol levels, poor sleep quality, and isolation (like on solo trips) can cause clear drops in mental health. People who travel often on long flights may face ongoing low mood, low energy, or burnout. Those with bipolar disorder must be careful, as jet lag might trigger manic or depressive episodes due to sudden changes in sleep and daily routines.
Sleep Disorders and Chronic Insomnia
Repeated jet lag episodes can upset the natural body clock so much that they lead to long-term sleep problems. The most common is insomnia, which includes:
- Trouble falling asleep
- Waking up often at night
- Waking too early
- Feeling tired during the day despite enough sleep
Some travellers develop disorders like:
- Delayed sleep phase (sleeping very late)
- Advanced sleep phase (waking very early)
- Irregular sleep patterns (broken sleep and naps throughout the day)
These problems may last long after travel and sometimes need sleep therapy, light treatment, or behaviour changes to fix.
Digestive and Gastrointestinal Disturbances
Jet lag affects more than sleep; it also disrupts digestion. The gut, like the brain, follows a body clock. Sudden time zone changes can cause:
- Loss of appetite
- Bloating or upset stomach
- Nausea or vomiting
- Constipation or diarrhea
In severe cases, ongoing digestive issues may cause poor nutrient absorption, weight loss, or flare-ups of irritable bowel syndrome (IBS). Hormones that control digestion get out of sync when meal times vary, which often happens on long trips. Also, dehydration, dry airplane air, and irregular eating can make stomach problems worse during and after flights.
Cardiovascular and Metabolic Risks
Although jet lag is not often seen as a heart risk, studies suggest long-term body clock disruption may raise the chance of:
- High blood pressure
- Heart palpitations or irregular heartbeats
- Higher resting heart rate
- Raised blood sugar levels
People with conditions like diabetes, heart disease, or metabolic problems may find symptoms worsen after long flights. Poor sleep and hormone changes (like insulin and cortisol) affect how the body controls energy, blood sugar, and blood pressure. Frequent travellers crossing five or more time zones many times each month may face higher long-term risks for heart and metabolic issues, especially without good recovery habits.
Immune System Suppression
Sleep is key for a strong immune system. Jet lag’s sleep disruption weakens the body’s defence against infections. Travellers with jet lag are more likely to catch:
- Colds and upper respiratory infections
- Flu or flu-like symptoms
- Stomach infections, especially when travelling abroad
- Slower healing of wounds or illnesses
Lack of sleep lowers production of infection-fighting proteins, cuts natural killer cell activity, and may reduce vaccine effectiveness. This is a concern for businesspeople, athletes, and healthcare workers often exposed to new germs.
Occupational and Safety Risks
People who must perform important tasks right after changing time zones—like pilots, drivers, doctors, or officials—face higher chances of mistakes if they do not manage jet lag well. These risks include:
- Medical or surgical errors
- Technical mistakes
- Drowsy driving or equipment use
- Weakened leadership during critical meetings
Employers and travel planners must think about these risks and allow time for rest before key work. Sports teams may also perform worse if they don’t plan to adjust their body clocks before competitions.
Jet Lag in Older Adults and Vulnerable Populations
Jet lag causes more problems in older adults, young children, and those with health issues. Aging lowers the body’s ability to reset its clock, so older travellers take longer to recover from long flights. They also face higher risks for heart, sleep, and thinking problems. People with dementia or Alzheimer’s may get confused or restless, with jet lag triggering agitation or wandering. Caregivers should watch these travellers carefully and give them extra time to rest and heal.
Final Thoughts
While many see jet lag as just a normal part of travel, its problems can be wide-ranging and serious. From poor mental focus and emotional stress to heart strain and weak immunity, the effects go beyond simple tiredness. People who travel long distances often—whether for work, sports, or personal reasons—must take jet lag seriously. By planning ahead, practicing good sleep habits, and using light, melatonin, and fluids wisely, most problems can be avoided. Knowing the risks helps you recover faster and keeps your health, work, and safety strong in all parts of life.
