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The Science Behind Jet Lag: How Our Body's Internal Clocks Are Affected

July 13, 2023 | Dr. Saad Zia

Traveling across several time zones can disrupt our body's internal clocks, leading to a phenomenon called jet lag, a temporary condition commonly associated with air travel. Jet lag affects the body's natural rhythm, significantly impacting our physical, emotional, and cognitive well-being. While it may be tempting to power through the symptoms of jet lag, it's important to understand how our body's internal clocks work and how we can minimize the effects of jet lag. In this blog post, we will dive deep into the science behind jet lag, explore the underlying physiological changes that occur during it, and provide strategies to minimize its impact on our bodies.

Understanding Jet Lag and Its Impact on the Body

Jet lag is a temporary condition that occurs when people travel across different time zones, leading to a disruption of their circadian rhythms, also known as internal clocks. The severity of jet lag can vary, ranging from mild to severe, depending on factors such as the number of time zones crossed, the direction of travel, and individual sleep patterns and habits. Common symptoms of jet lag include difficulty falling asleep or staying asleep, daytime fatigue, irritability, gastrointestinal discomfort, and memory impairment. These symptoms can span several days or weeks, depending on an individual's ability to adapt to the new time zone.

Understanding the Body's Internal Clocks: Circadian Rhythms

Circadian rhythms are natural biological processes regulating various bodily functions, including sleep, hormone secretion, and metabolism. These rhythms are controlled by a specialized region in the brain called the suprachiasmatic nucleus (SCN). The SCN receives information from our eyes about the light and darkness in our environment. Based on this input, the SCN effectively coordinates the production and release of important hormones like melatonin, which are crucial in maintaining a balanced sleep-wake cycle. Ensuring the right timing and levels of these hormones, our body's internal clocks help us maintain a healthy and well-functioning daily rhythm.

 The Role of Light in Regulating Circadian Rhythms

Light plays a crucial role in regulating the circadian system. Exposure to natural sunlight during the day is essential for resetting the body's internal clock.  Specifically, the blue light emitted by the sun acts as a vital signal to suppress melatonin production, indicating to our bodies that it is time to be awake and engaged. Conversely, darkness prompts the release of melatonin, facilitating the process of falling asleep and maintaining sleep. By intentionally exposing ourselves to bright light in the morning or minimizing our exposure to blue light in the evening, we can effectively reset our body's internal clocks and reduce the impact of jet lag. These actions aid in synchronizing our circadian rhythms with our new time zone.

Disrupting the Internal Clock: Causes and Effects of Jet Lag

Jet lag can arise from various factors, including the number of time zones crossed, the direction of travel, the duration of the journey, and an individual's sleep patterns. Factors like stress, dehydration, and caffeine consumption can intensify jet lag further. When the circadian rhythm is disrupted, it sets off a series of physiological changes within the body. These changes encompass shifts in hormone levels, fluctuations in appetite and metabolism, and disturbances in the sleep-wake cycle. Consequently, a range of symptoms emerges, making it challenging to maintain normal functioning.

The Science of Time Zones and Jet Lag Severity

The severity of jet lag can vary depending on the specific time zones crossed during travel, as supported by extensive research in the field. Scientific studies have contributed to developing mathematical models that accurately predict the potential severity of jet lag. These models consider factors such as the direction of travel and the number of time zones crossed. By utilizing this knowledge, travelers can gain valuable insights into the expected effects of jet lag and proactively prepare for the associated symptoms.

The direction of travel is a significant factor in determining the severity of jet lag symptoms. Eastward journey, such as traveling from the United States to Europe, often leads to more severe jet lag due to the necessity of advancing the body's internal clock. Conversely, westward travel, such as traveling from Europe to the United States, may result in milder symptoms as the body's internal clock is delayed. Understanding the effects of different time zones can assist travelers in better preparing for and managing the symptoms of jet lag.

Physiological Changes During Jet Lag: Sleep Patterns and Hormonal Shifts

Jet lag can significantly impact our sleep patterns by disrupting the natural circadian rhythm that regulates our sleep-wake cycle. When we travel across different time zones, our body's internal clock becomes out of sync with the local time, leading to difficulty falling asleep and staying asleep at the appropriate times. This disruption can result in feelings of daytime fatigue and nighttime restlessness.

In addition to affecting sleep, jet lag also triggers hormonal shifts within our body. One notable change is the alteration in the production and release of cortisol, a hormone closely linked to our stress response. The fluctuation in cortisol levels can influence various aspects of our well-being, including metabolism, appetite regulation, and stress levels. These hormonal changes contribute to the overall challenges and symptoms experienced during jet lag.

By understanding the physiological changes that occur during jet lag, such as disrupted sleep patterns and hormonal shifts, individuals can better comprehend its wide-ranging effects on their bodies. This awareness can aid in developing strategies and interventions to mitigate the impact of jet lag and promote a quicker adjustment to the new time zone.

Cognitive and Behavioral Effects of Jet Lag

In addition to its physical effects, jet lag can significantly impact our cognitive and behavioral performance. Extensive studies have shown that jet lag has the potential to impair our memory and attentional processes, making it difficult to remember and concentrate effectively. Furthermore, it can influence our mood, motivation, and reaction time, leading to fluctuations in emotional well-being. These cognitive and behavioral changes associated with jet lag can result in decreased productivity, reduced work performance, and increased irritability.

The cognitive effects of jet lag can manifest as difficulties in thinking, processing information, and making decisions. Individuals may experience memory lapses, reduced mental alertness, and a general sense of mental fog. These cognitive impairments can hinder performance in various tasks, both at work and in daily activities.

Furthermore, jet lag can impact our behavior and emotional state. Individuals may feel irritable, moody, or emotionally sensitive due to the disruption of their body's internal clocks. The lack of quality sleep and the adjustment to a new time zone can contribute to these changes in mood and emotional well-being.

Recognizing jet lag's potential cognitive and behavioral effects is crucial for individuals who frequently travel across time zones. By understanding these impacts, individuals can proactively manage and mitigate the challenges they may face.

Strategies for Minimizing Jet Lag: Adjusting Sleep, Light Exposure, and Meal Times

Implementing certain strategies before traveling can effectively minimize the effects of jet lag. One highly recommended approach is gradually adjusting your sleeping schedule in the days leading up to your departure. This involves shifting your sleep and wake times closer to the anticipated time zone of your destination. Doing so allows your body to adapt to the new schedule in advance, making the transition smoother.

In addition to adjusting your sleep, aligning your exposure to light and meal times with the local time zone at your destination is beneficial. Exposure to natural sunlight during the day and avoiding bright light in the evening can help regulate your body's internal clock. This signals to your body when it's time to be awake and when it's time to wind down for sleep. Similarly, adjusting your meal times to match the local time zone can help synchronize your body's digestive processes with the new schedule.

On the day of travel, it is advisable to avoid consuming heavy meals, alcohol, and caffeine. Heavy meals can disrupt digestion and make it harder for your body to adjust to the new time zone. Alcohol and caffeine can interfere with your sleep patterns and exacerbate the symptoms of jet lag. Staying hydrated by drinking plenty of water throughout the journey is also essential for supporting your body's functions and minimizing the effects of dehydration.

By incorporating these strategies into your travel routine, you can significantly mitigate the impact of jet lag on your well-being. These adjustments help your body adapt to the new time zone more smoothly, allowing you to cope with and recover from jet lag more effectively. Everyone’s response to jet lag can vary, so it's important to experiment with different strategies and find what works best for you.

The Role of Melatonin in Jet Lag Recovery

Melatonin, a hormone produced in the brain, is crucial in regulating the body's natural sleep-wake cycle. It is involved in the initiation and maintenance of sleep. As a result, melatonin supplementation is often utilized to assist in managing jet lag. Numerous studies have demonstrated that taking melatonin supplements at the appropriate time based on the local time zone of the destination can significantly alleviate the symptoms of jet lag and enhance the quality of sleep. However, it is important to consult with a healthcare professional regarding the optimal timing and dosage of melatonin supplements for jet lag recovery.

Technology and Jet Lag: Can Gadgets Help or Hinder Recovery?

The development of technology has introduced various gadgets, apps, and wearable devices to assist travelers in managing jet lag symptoms. Such technologies include wearable sleep trackers, light therapy devices, and mobile applications offering personalized sleep schedules and recommendations based on circadian rhythms.

However, the effectiveness of these interventions in managing jet lag symptoms remains a topic of ongoing research and discussion within the medical community. While some individuals have reported positive outcomes using wearable sleep trackers to monitor and optimize their sleep patterns, the evidence supporting their effectiveness for jet lag is limited. Similarly, while light therapy devices have shown promising results in regulating circadian rhythms, their impact on jet lag management requires further investigation.

Travelers must assess the available evidence from reputable sources and consult with healthcare professionals to determine the most appropriate and evidence-based approach for managing their jet lag. This individualized approach ensures that any technology utilized is based on scientific research, aligns with their specific needs, and maximizes the chances of effectively managing jet lag symptoms.

 Jet Lag and Shift Work: Similarities and Differences in Effects

Both shift work and jet lag can disrupt the body's natural circadian rhythm, leading to various physiological, cognitive, and behavioral symptoms. However, there are notable distinctions between the two.

Jet lag is a temporary disruption experienced during travel when crossing different time zones. It occurs as the body's internal clock becomes desynchronized with the local time. Jet lag can be managed by implementing appropriate pre-trip and post-trip strategies, allowing individuals to minimize its impact and gradually readjust their internal clocks to the new time zone.

On the other hand, shift workers face repeated episodes of circadian disruption due to their work schedule. Shift work involves rotating shifts and irregular schedules, making adjusting to varying sleep-wake cycles challenging. Unlike jet lag, a transient condition, shift workers regularly encounter the difficulties associated with circadian disruption over a prolonged period.

Both jet lag and shift work can adversely affect individuals' well-being. They can result in similar physiological, cognitive, and behavioral symptoms, such as sleep disturbances, impaired concentration, mood changes, and decreased performance. However, the management approaches differ.

For jet lag, implementing strategies like adjusting sleep schedules, light exposure, and meal times can help individuals minimize its impact and facilitate the adjustment to the new time zone. These strategies are usually applied during travel and shortly after returning home.

In contrast, shift workers require long-term strategies to mitigate the effects of circadian disruption. This may involve consistent sleep schedules, optimizing light exposure during shifts, and establishing healthy sleep habits. Additionally, shift workers may benefit from workplace interventions such as optimizing shift rotation patterns, providing sufficient breaks, and creating a sleep-friendly environment.

By addressing the specific challenges associated with circadian disruption, individuals can work towards minimizing the negative effects and promoting better overall well-being.

Jet Lag in Special Populations: Children, Older Adults, and Pregnant Women

Jet lag can affect special populations in distinct ways, including children, older adults, and pregnant women. Understanding these effects is important for implementing appropriate precautions and seeking medical guidance.

Children are particularly vulnerable to experiencing severe symptoms of jet lag. This susceptibility may be due to their developing internal clocks and heightened sensitivity to disruptions. Parents and caregivers should be aware of the potential impact on children and take additional measures to minimize the effects of jet lag. Establishing consistent sleep schedules, ensuring proper rest before and after travel, and gradually adjusting sleep routines can help children adapt more smoothly to the new time zone.

Older adults may face challenges adjusting to new time zones due to age-related changes in their circadian rhythms. The natural decline in the flexibility of the internal clock can make it more difficult for older adults to synchronize with the local time. Older travelers must prioritize sleep hygiene, maintain a regular sleep schedule, and consider adjusting sleep and light exposure patterns per the new time zone. Seeking medical advice and discussing specific concerns with healthcare professionals can also be beneficial.

Pregnant women should take additional precautions when it comes to jet lag. The disruption of sleep patterns and hormonal changes induced by jet lag can have implications for both the mother and the developing fetus. Pregnant women should prioritize adequate rest, ensure good sleep hygiene, and consider adjusting sleep and light exposure to support their body's adaptation to the new time zone. Consulting with healthcare professionals regarding specific recommendations and potential risks associated with jet lag during pregnancy is essential for the well-being of both the mother and the baby.

The Future of Jet Lag Research: Novel Interventions and Therapies

Ongoing research is actively exploring various innovative therapies and interventions to reduce the impact of jet lag. For example, scientists are investigating the use of chronobiological agents, which are substances that target the body's internal clocks and help adjust them to new time zones. These agents could include melatonin supplements or light therapy, which have shown promising results in regulating circadian rhythms and reducing jet lag symptoms. Additionally, behavioral interventions such as strategic sleep scheduling and exposure to natural light are being studied to help travelers adjust their circadian rhythms more efficiently. These emerging approaches offer significant potential for improving the management of jet lag and developing more effective strategies to alleviate its symptoms. With ongoing scientific advancements, new interventions and therapies will likely be developed to enhance the overall travel experience and minimize the disruptive effects of jet lag.


Jet lag can be a frustrating and debilitating condition that significantly impacts our physical, emotional, and cognitive well-being. However, with a better understanding of the body's internal clocks and the strategies for managing jet lag, travelers can take steps to minimize the effects of this condition. Whether it's adjusting sleep, light exposure, and meal times or using supplements, wearable devices, and light boxes, various interventions are available to help travelers navigate the effects of jet lag. Proper preparation and post-trip care allow travelers to enjoy optimal travel experiences with minimal disruption to their bodies natural rhythms.

At Cura4U, we recognize the importance of addressing sleep disorders and their impact on overall well-being. If you're struggling with jet lag or other sleep-related issues, seeking professional help can greatly benefit you. Our dedicated SleepRx Clinic offers specialized evaluation and personalized treatment plans for various sleep disorders, including jet lag-related ones. Our experienced team understands that quality sleep is essential for physical and mental restoration. Addressing and managing your sleep disorder can significantly enhance your overall well-being and enjoy a more rejuvenating travel experience. Don't hesitate to schedule an appointment at SleepRx Clinic and take a step towards better sleep and improved quality of life. Remember, a well-rested body sets the foundation for a productive and energized day, no matter where your travels take you.


Our clinical experts continually monitor the health and medical content posted on CURA4U, and we update our blogs and articles when new information becomes available. Last reviewed by Dr. Tayyab Saeed Akhter on July 13th, 2023.




Jet Lag: Symptoms: Causes, and How to Cope | Sleep Foundation-

Jet Lag | Travelers' Health | CDC-

The prevention and treatment of jet lag - PMC (

Jet Lag | University Health Service (

Sleeplessness and Circadian Rhythm Disorder: Practice Essentials, Background, Etiology (

Jet lag - UpToDate-

What works for jetlag? A systematic review of non-pharmacological interventions - PubMed (

The pathophysiology of jet lag - ScienceDirect-

Managing jet lag: Some of the problems and possible new solutions - ScienceDirect-

Chronic Jet Lag Produces Cognitive Deficits (

Jet lag disorder - Symptoms and causes - Mayo Clinic-

Jet Lag: What is it, Symptoms, How Long Does it Last & Treatment (

Jet Lag - PMC (

Frontiers | Interventions to Minimize Jet Lag After Westward and Eastward Flight (

Identifying some determinants of “jet lag” and its symptoms: a study of athletes and other travellers | British Journal of Sports Medicine (

Melatonin, light therapy, and jet lag - ScienceDirect-





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