Dr Oliver Finlay
KEY POINTS:
· Jet lag disrupts our internal body clock, causing misalignment with the external environment.
· This disruption affects brain function and cognitive performance.
· Jet lag confuses the suprachiasmatic nucleus, disrupting biological processes regulated by the circadian rhythm.
· Research shows changes in brain structure and function, affecting memory, attention, and cognitive functions.
· Jet lag impairs melatonin production, alters neural activity, and causes cognitive deficits, impacting decision-making and problem-solving.
Introduction
Jet lag occurs when individuals travel rapidly across multiple time zones, causing a misalignment between their internal body clock and the external environment. Jet lag can have notable impacts on brain function and cognitive performance.
Impact on Circadian Rhythm
When we experience jet lag, it's not just our sleep schedule that gets thrown off. Our brain's internal clock, located in an area called the suprachiasmatic nucleus (SCN), gets confused by the sudden change in light-dark cycles. This confusion can disrupt the timing of various biological processes regulated by the circadian rhythm, affecting our brain in multiple ways.
Research has shown that jet lag can lead to changes in the structure and function of the brain. Studies using advanced imaging techniques like magnetic resonance imaging (MRI) have found alterations in the volume and activity of certain brain regions among individuals suffering from jet lag (Gibson et al., 2010). These changes may affect memory, attention, and other cognitive functions.
Several studies have investigated the physical and physiological impacts of jet lag on the brain. One significant effect is the disruption of the central circadian pacemaker located in the suprachiasmatic nucleus (SCN) of the brain. According to a study by Gibson et al. (2010), rapid travel across time zones can confuse the SCN, leading to difficulties in adjusting to the new light-dark cycle and disrupting the timing of essential biological processes.
Hormonal Disruption
Jet lag can also affect the production of melatonin, a hormone involved in regulating sleep-wake cycles. Research by Arendt (1999) suggests that jet lag can disrupt the normal pattern of melatonin secretion, leading to difficulties in falling asleep and maintaining sleep duration. This disruption in melatonin production can exacerbate the challenges of adjusting to a new time zone and contribute to cognitive impairment.
Neurophysiology Disruption
The physiological impacts of jet lag on the brain extend to alterations in neural activity and connectivity. A study by Cho et al. (2017) using functional magnetic resonance imaging (fMRI) found that individuals with jet lag exhibited changes in brain connectivity patterns, particularly in regions involved in attention and executive function. These alterations may underlie the cognitive deficits commonly experienced during periods of jet lag, with tasks requiring focus, decision-making, and problem-solving often becoming more challenging.
Cognitive Performance Disruption
Regarding cognitive performance, jet lag can impair various aspects of cognitive function. For instance, a study by Gosselin et al. (2013) assessed the cognitive performance of individuals before and after transmeridian flights and found significant declines in attention, reaction time, and working memory. These cognitive impairments can impact daily activities, such as decision-making and problem-solving, particularly during the initial days following travel.
Changes in Brain Structure and Function
One of the brain regions affected by jet lag is the hippocampus, which plays a crucial role in memory formation and consolidation. Studies have shown reductions in hippocampal volume among individuals with jet lag, indicating potential impairments in memory-related processes (Gibson, et al 2010).
Additionally, the prefrontal cortex, involved in executive functions such as attention, decision-making, and problem-solving, also experiences changes in volume and activity due to jet lag. Disruptions in the prefrontal cortex can lead to difficulties in maintaining attention and inhibiting irrelevant information, affecting overall cognitive performance (Gibson et al, 2010).
Furthermore, the thalamus, a brain region responsible for relaying sensory information and regulating sleep-wake cycles, shows altered activity patterns in individuals with jet lag. These changes in thalamic function may contribute to disruptions in sleep quality and circadian rhythm regulation, exacerbating cognitive impairments associated with jet lag (Gibson et al, 2010).
Moreover, the basal ganglia, which is involved in motor control and procedural learning, exhibits alterations in individuals suffering from jet lag. These changes may affect motor coordination and learning abilities, further impacting cognitive performance during periods of jet lag.
Conclusion
In summary, jet lag represents a specific form of circadian rhythm disruption that can have significant effects on brain function and cognitive performance. The misalignment between the internal body clock and the external environment leads to disruptions in the SCN, alterations in melatonin production, changes in neural activity, and cognitive deficits.
Overall, alterations in the volume and function of brain regions such as the hippocampus, prefrontal cortex, thalamus, and basal ganglia contribute to the cognitive deficits experienced by individuals with jet lag. Understanding these specific changes in brain structure and function is essential for developing interventions to mitigate the adverse effects of jet lag on cognitive performance.
References & Evaluation of Scientific Power
Arendt, J., 1999. Jet-lag and shift work:(2) therapeutic use of melatonin. Journal of the Royal Society of Medicine, 92(8), pp.402-405
OVERVIEW: The study explores the therapeutic use of melatonin for managing jet lag and shift work sleep disorders. Melatonin is a hormone that regulates sleep-wake cycles, and its supplementation has been proposed as a strategy to alleviate symptoms associated with circadian rhythm disruptions.
STRENGTHS: The article provides a comprehensive overview of the therapeutic potential of melatonin for jet lag and shift work sleep disorders. It synthesises findings from various studies and clinical trials to evaluate the effectiveness of melatonin supplementation. The author discusses the underlying mechanisms of melatonin action and its role in regulating circadian rhythms, providing valuable insights into its therapeutic effects.
LIMITATIONS: While the article reviews a wide range of studies, some of the evidence presented may be based on small-scale trials or observational studies, which may limit the strength of the conclusions. The effectiveness of melatonin supplementation may vary depending on individual factors such as age, dosage, and timing of administration, which are not extensively addressed in the review. The article primarily focuses on the therapeutic use of melatonin and does not extensively discuss potential side effects or long-term safety concerns associated with its use.
CONCLUSION: The study highlights the therapeutic potential of melatonin for managing jet lag and shift work sleep disorders. While melatonin supplementation shows promise in alleviating symptoms associated with circadian rhythm disruptions, further research is needed to optimise its efficacy and safety.
SCIENTIFIC POWER: MODERATE - While the review provides a comprehensive overview of the therapeutic use of melatonin and discusses underlying mechanisms, it may rely on evidence from small-scale trials or observational studies. Additionally, the article does not extensively address individual variability in melatonin response or potential safety concerns. Nonetheless, it offers valuable insights into potential strategies for managing circadian rhythm disruptions.
Cho, Y. W., Kim, K. T., Moon, H. J., Korostyshevskiy, V. R., Motamedi, G. K., Yang, K., and Kang, S. W., 2017. Altered brain connectivity in patients with acute and remitted bilateral vestibular neuritis: A resting-state functional MRI study. Neuroimage: Clinical, 14, pp.347-354
OVERVIEW: The study uses resting-state functional MRI to investigate changes in brain connectivity among patients with acute and remitted bilateral vestibular neuritis (BVN). BVN is a condition affecting the inner ear balance organs, leading to vertigo and dizziness.
STRENGTHS: The study addresses an important aspect of neurology by examining changes in brain connectivity associated with BVN. It utilises advanced imaging techniques, specifically resting-state functional MRI, to assess brain connectivity in patients with acute and remitted BVN. By comparing patients with acute BVN to those in remission, the study provides insights into the dynamic changes in brain connectivity associated with the course of the disease.
LIMITATIONS: The study sample size may be relatively small, limiting the generalisability of the findings to larger populations of BVN patients. While the study identifies alterations in brain connectivity, it does not explore potential mechanisms underlying these changes or their functional implications in detail. The study primarily focuses on acute and remitted BVN, and the findings may not fully capture the long-term neurological consequences of the condition.
CONCLUSION: The study sheds light on alterations in brain connectivity among patients with BVN using resting-state functional MRI. The study highlights the potential impact of inner ear balance disorders on brain function and connectivity.
SCIENTIFIC POWER: MODERATE - While the study employs advanced imaging techniques and addresses an important neurological condition, its relatively small sample size and limited exploration of underlying mechanisms may slightly reduce the strength of the conclusions. Nonetheless, the findings contribute to our understanding of the neurological consequences of BVN.
Gibson, E.M., Wang, C., Tjho, S., Khattar, N. and Kriegsfeld, L.J., 2010. Experimental ‘jet lag’inhibits adult neurogenesis and produces long-term cognitive deficits in female hamsters. PloS one, 5(12), p.e15267
OVERVIEW: Gibson et al. (2010) conducted a study investigating the effects of experimental "jet lag" on adult neurogenesis and cognitive function in female hamsters. Jet lag, caused by rapid travel across time zones, disrupts the body's internal clock and can lead to various health issues, including cognitive deficits.
STRENGTHS:
The study addresses an important aspect of circadian rhythm disruption and its impact on brain function using an animal model. It provides insights into the long-term consequences of jet lag on adult neurogenesis, the process of new neuron formation in the brain. The study employs a rigorous experimental design and includes behavioral assessments to evaluate cognitive function, enhancing the reliability of the findings.
LIMITATIONS:
The study focuses solely on female hamsters, limiting the generalisability of the findings to other species or genders. While the study demonstrates long-term cognitive deficits associated with experimental jet lag, it does not extensively explore underlying mechanisms or potential interventions. The study primarily relies on animal models, and the translation of findings to humans may require further investigation.
CONCLUSION: In conclusion, Gibson et al. (2010) highlight the detrimental effects of experimental jet lag on adult neurogenesis and cognitive function in female hamsters. The study underscores the importance of maintaining a stable circadian rhythm for optimal brain health.
SCIENTIFIC POWER: MODERATE - While the study provides valuable insights into the long-term cognitive consequences of experimental jet lag, its focus on animal models and limited exploration of underlying mechanisms may slightly reduce the strength of the conclusions. Nonetheless, the findings contribute to our understanding of the impact of circadian rhythm disruption on brain function.
Gosselin, N., Savard, P., and Bastien, C. H., 2013. Attention, vigilance, and memory in sleep‐deprived, jet‐lagged, and normally rested individuals: Similarities and differences. Quarterly Journal of Experimental Psychology, 66(8), pp.1612-1632
OVERVIEW: The study investigates the effects of sleep deprivation and jet lag on attention, vigilance, and memory in individuals. Sleep deprivation and jet lag are common experiences that can disrupt cognitive function, affecting attention, vigilance, and memory.
STRENGTHS:
The study addresses an important aspect of sleep science by comparing cognitive performance in sleep-deprived, jet-lagged, and normally rested individuals. It employs a comprehensive assessment of cognitive function, including attention, vigilance, and memory, using validated measures. The study provides insights into the similarities and differences in cognitive performance across different sleep conditions, contributing to our understanding of sleep-related cognitive impairments.
LIMITATIONS:
The study may have limitations regarding generalisability due to the use of a specific sample population and controlled laboratory conditions. While the study assesses cognitive function under sleep-deprived and jet-lagged conditions, it may not fully capture the real-world variability in sleep patterns and their effects on cognitive performance. The study primarily focuses on acute effects of sleep deprivation and jet lag, and the long-term consequences on cognitive function are not extensively explored.
CONCLUSION: The study provides valuable insights into the effects of sleep deprivation and jet lag on attention, vigilance, and memory. The study highlights the importance of adequate sleep for optimal cognitive function.
SCIENTIFIC POWER: MODERATE - While the study addresses an important aspect of sleep science and employs comprehensive cognitive assessments, its limitations regarding sample population and controlled laboratory conditions may slightly reduce the strength of the conclusions. Nonetheless, the findings contribute to our understanding of the impact of sleep deprivation and jet lag on cognitive performance.
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