Jet lag is commonly associated with long international flights and changing time zones. However, doctors are increasingly warning about a lesser-known but equally disruptive phenomenon, jet lag without travel. Known as "internal jet lag," this condition can occur when festive routines, late-night celebrations, irregular meals, and poor sleep hygiene interfere with the body's internal clock. During holidays and year-end celebrations, many people experience sleep deprivation, daytime fatigue, irritability, and digestive issues, symptoms often dismissed as temporary tiredness. But experts say these changes reflect a deeper biological disturbance of the circadian rhythm, the body's natural 24-hour clock that regulates sleep, hormones, metabolism, and energy levels.
"Holiday routines may feel harmless and relaxing, but even a few nights of disrupted sleep can confuse your body clock," says Dr Hari Kishan Boorugu, Consultant Physician & Diabetologist, Yashoda Hospitals, Hyderabad. He explains that stress from celebrations, late-night screen use, alcohol consumption, and erratic schedules can push the body into a jet lag-like state, even without boarding a plane. Left unaddressed, internal jet lag can affect not just sleep but also mental well-being, cardiovascular health, and long-term disease risk, making it a growing public health concern.
What Is the Circadian Rhythm and Why Does It Matter?
The circadian rhythm is a 24-hour biological cycle regulated by the brain's suprachiasmatic nucleus. It responds primarily to light and darkness, guiding essential functions such as sleep-wake cycles, hormone release, body temperature, digestion, and alertness.
According to the National Institute of General Medical Sciences (NIGMS, NIH), circadian rhythms influence nearly every tissue and organ in the body. When this internal clock is aligned, the body functions efficiently. When disrupted, physiological balance is lost.
Dr Boorugu explains, "When the circadian rhythm is disturbed, the body struggles to stay balanced. Sleep quality declines, digestion suffers, and energy levels fluctuate unpredictably."
How Festive Routines Disrupt the Body Clock
Holidays often bring a perfect storm of circadian disruptors:
- Late-night social gatherings
- Irregular sleep and wake times
- Excessive alcohol and caffeine
- Heavy, late-night meals
- Prolonged exposure to bright lights and screens
- Emotional and physical stress from hosting and celebrations
These habits confuse the brain's perception of day and night, delaying sleep signals and impairing recovery. Research published by the National Center for Biotechnology Information (NCBI) shows that even short-term circadian misalignment can negatively affect metabolic and cardiovascular health.
Melatonin: The Sleep Hormone That Takes the Hit
Melatonin, produced by the pineal gland, acts as the body's natural sleep switch. Its release rises in the evening with darkness, peaks at night, and falls with morning light.
"Festive routines such as late nights, bright lights, screen use, alcohol, and stress can suppress or delay melatonin," explains Dr Boorugu. "When this cycle is disturbed, sleep quality declines, leading to fatigue, irritability, and mood changes."
The Sleep Research Society notes that suppressed melatonin disrupts sleep architecture, increasing the risk of insomnia and daytime exhaustion. Protecting melatonin's rhythm is critical, as once it is pushed out of sync, the body struggles to rest and recover.
Symptoms of Internal Jet Lag to Watch For
Internal jet lag does not affect sleep alone. Common symptoms include:
- Difficulty falling or staying asleep
- Daytime fatigue and low energy
- Irritability and mood swings
- Poor concentration and memory lapses
- Digestive discomfort and bloating
- Palpitations or changes in heart rhythm
"Even young adults without prior illness can experience blood pressure spikes or heart rhythm changes," warns Dr Boorugu.
Long-Term Health Risks of Ignoring Sleep Disruption
While short-term effects include tiredness and poor focus, long-term circadian disruption can have serious consequences. Studies from the World Health Organization (WHO) and European Society of Cardiology link chronic sleep irregularity with:
- Increased risk of depression and anxiety
- Cardiovascular disease and hypertension
- Metabolic disorders such as diabetes
- Higher risk of stroke
Ignoring these warning signs can make recovery harder and prolong physiological stress.
How to Reset Your Body Clock After the Holidays
Doctors recommend simple, consistent steps to restore circadian balance:
- Maintain fixed sleep and wake times, even on weekends
- Get morning sunlight exposure to reset the brain clock
- Avoid alcohol, caffeine, and heavy meals late at night
- Reduce screen use at least one hour before bedtime
- Stay hydrated and practice stress-management techniques
"Internal jet lag is real. It affects mood, digestion, and heart health," says Dr Boorugu. "The best gift you can give yourself as a New Year's resolution is a proper routine with timely sleep."
Jet lag without travel is a silent but growing health issue during festive seasons. While celebrations are important, prolonged disruption of sleep and routine can confuse the body's internal clock with lasting consequences. Recognising internal jet lag early and restoring healthy rhythms can protect sleep, mental well-being, and long-term heart health, ensuring that the new year begins on a truly healthy note.
Disclaimer: This content, including advice, provides generic information only. It is in no way a substitute for a qualified medical opinion. Always consult a specialist or your own doctor for more information. NDTV does not claim responsibility for this information.
