By Dr Mitchell Turner, Dr John Caldwell and Dr Ian Dunican
Managing travel and jet lag is extremely important. Many people report that when they undertake long bouts of travel (Air, Sea, Land) across 3 or more time zones (interstate or internationally), they feel sleepy, sluggish, or tired from the travel-related body-clock disruptions to the extent that they are unable to perform at their best during practice and even during competition until they have adapted to the new time zone.
The problems stemming from these disruptions can be exacerbated by many factors such as temperature extremes and high altitudes at the destination, underlying sleep disorder (currently affects 20% of the population), advancing age, excessive body mass index, training or workload, stress, digestive issues, or respiratory problems. Therefore, effectively managing these factors is crucial for optimising adaptation and performance.
At Melius Consulting, we have designed travel and flight schedule advice and strategic support with many mining companies, oil and gas and high-risk industries to ensure fitness for work in remote areas and fly in and fly out to optimise performance such as BHP, Rio Tinto, Fugro, Woodside, Anglo Gold Ashanti and many more. We have completed such work in Formula 1 for the week/s leading up to practice, qualifying and race day to gain a 20% improvement in alertness that required the inclusion of travel, media, team meetings and sponsor obligations. In MMA and BJJ (see YouTube video here), we have designed plans incorporating travel, jet lag, weight cutting, media, and training periods and in Super Rugby (see YouTube video here). Dr John Caldwell is a world expert in this area. John holds the US Air Force’s highest civilian award for research and development; he is a Fellow of the Aerospace Medical Association and a Fellow of the Aerospace Human Factors Society. He has worked with various organisations, including the US Army’s Medical Research and Materiel Command, the National Aeronautics and Space Administration, and the US Air Force Research Laboratory. He provides education on research issues and strategies to optimise performance in real-world contexts.
When discussing travel, fatigue, and jet lag, it is essential to distinguish between travel fatigue and jet lag. Travel fatigue may or may not result in jet lag. We will use the term travel fatigue concerning the journey to a destination. This can be undertaken in any transport mode, such as a car, bus, train, ferry, or air travel. Travel fatigue does not require rapid movement through time zones (east or west)(1). Travel fatigue is when we travel across < 3 time zones.
Travel fatigue can be attributed to the following factors: frequency of travel, duration of the journey, and cumulative travel over some time (i.e., within proximity to a business meeting or holiday). Travel fatigue syndrome involves generalised fatigue, occasional headache, and mental weariness because of a distorted sleep routine. This may occur due to the stress of travel, hours of sustained wakefulness, sleep loss or deprivation of a sleep period due to being in a confined space for an extended period, with restricted movement, and exposure to dry air, possibly causing dehydration (2). An important distinction is that travel fatigue does not depend on the number of time zones traversed. It can occur after northbound or southbound travel. Restful sleep generally abolishes the symptoms of travel fatigue (3). However, with lots of travel, the deleterious effects may be cumulative over time and may prove to be potentially detrimental to your performance (4). Travel fatigue may also result in illness, impact and variation on mood and motivation (5).
Jet lag is a circadian rhythm disorder that is a temporary condition that is alleviated over time, from one day to up to two weeks for some individuals (6). So, what happens to us when we experience jet lag?
- Excessive daytime sleepiness or distortion of the sleep cycle along with decreased total sleep time that coincides with jet travel across at least two time zones (east to west or west to east)
- Generalised fatigue or the presence of somatic symptoms occurring within two days of travel onset.
- No other disorder or condition can be attributed to sleep disturbance.
This will be mild jet lag when we cross 3-5 time zones. When we travel more than 5 time zones, jet lag causes circadian disruption, making sleep difficult and affecting your daily decision-making, reaction time and problem-solving capability. Jet lag is a recognised circadian rhythm sleep disorder and can result in disturbed sleep, increased fatigue, headaches, and gastrointestinal disturbances (7). Jet lag occurs when travelling rapidly across several time zones due to an unadjusted body clock in a new time zone. Meaning that all daily rhythms, termed circadian rhythms, controlled by the body clock are inappropriately phased (8). As the body clock adjusts to the new time zone, the symptoms of jet lag are reduced.
For example, crossing multiple time zones in either an easterly (e.g., Los Angeles to New York, United States of America) or westerly direction (London, England to New York, US) causes jet lag. However, travelling from north to south within the same or similar time zone (Beijing, China to Perth, Australia) does not result in jet lag. However, it may cause fatigue to an individual due to the time spent travelling or acute sleep disruption from an overnight flight. This is often referred to as travel fatigue and may occur in the short term or maybe accrued over a season that requires a significant amount of travel and thus impacts recovery and performance.
Whenever >3 time zones are crossed, disagreements between the body’s internal clock and the clock on the wall can wreak havoc if not properly managed. To get a grip on this issue, consider that humans have several internal physiological processes that affect sleepiness and performance. These are usually tuned to a well-synchronised 24-hour rhythm which is kept right on schedule by the timing of sunlight exposure, at least if the schedule is consistent regarding morning wakeups, daytime activity, and nightly bedtimes. In this situation, the body’s time and the environmental time are closely aligned, and the body’s rhythms are in harmony. But when travel-related time changes occur, problems arise because the body’s sense of time lags behind the time cues in the new environment. Since this is a phenomenon of modern airline transportation, it has been labelled “jet lag”.
A general rule of thumb is that you should allow 1 day to adjust for every time zone crossed. For example, a trip from London, United Kingdom, to Perth, Australia, in an easterly direction may take up to 8 days. Conversely, travelling westwardly is slightly easier, and you should allow ½ day for every time zone crossed to adjust. A trip from London, United Kingdom, to New York may only take 2 ½ to 3 days as there are 5 time zones crossed.
There are numerous valid behavioural and environmental strategies to reduce the symptoms of jet lag, including timed light exposure, shift in sleep timings and to add stopovers during travel (7-9). In addition to these strategies, advice on supplementation and food/drink intake is becoming more common (10).
However, there is a need for more scientific evidence to support their use. Below are some of the most common supplements and foods/drinks used to reduce jet lag symptoms and the evidence supporting their use.
Exogenous (external from the body) melatonin is both a chronobiotic and a hypnotic, meaning it can shift the timing of the circadian system (11). However, it can also make falling and staying asleep easier (12). In addition, the time of day significantly impacts the effects of melatonin; for example, if ingested at night (when endogenous melatonin is high), exogenous melatonin will not increase sleepiness (9). Conversely, if consumed during the day (when endogenous melatonin is low), exogenous melatonin will increase drowsiness (13). Therefore, melatonin has been shown to effectively shift the circadian clock and reduce jet lag (9).
Action: Specifically, if you are required to phase advance (shift your body clock earlier), melatonin should be taken in the afternoon; if you are required to phase delay (move your body clock later), melatonin should be taken in the morning.
Caffeine is readily available in many forms, including tablets, gums, candies, beverages and foods. An 8-fl oz cup of drip-brewed coffee contains an average of 135 mg of caffeine, an 8-fl oz cup of brewed tea contains approximately 50 mg of caffeine, and a 12-fl oz cola drink has an average of 44 mg of caffeine. An 8-fl oz cup of Starbucks coffee contains 250 mg of caffeine. Melatonin rhythm is delayed consistently by 40 min when 200 mg of caffeine is taken 3 hr before bedtime (14). Caffeine has also been reported to aid in accelerating the resynchronisation of the body clock when taken in accordance with the destination time zone (15). However, it may have detrimental effects on sleep initiation and quality if taken before sleep periods and, therefore, should be used with caution. Recent research shows that caffeine may impact your sleep when consumed within 8 hrs of bedtime (16).
Figure 1: Meta-analytic model accounting for both the timing and the amount of the final caffeine dose (16).
Action: When travelling, stop consuming coffee within 8 hrs of sleep to ensure you can fall asleep. Caffeine may be used as an aid to stay awake when appropriate to accelerate the time it takes to re-synchronise your body clock to the destination time (e.g., taken in the morning of the destination time zone).
While drinking water cannot reduce jet lag, it can reduce travel fatigue which is often mistaken for jet lag as it commonly occurs after a long flight. Furthermore, the symptoms of jet lag may be exacerbated if dehydration occurs. Therefore, it is essential to stay hydrated while flying since dehydration can be exacerbated due to pressure and dry cabin air (17).
Action: Slightly higher than regular fluid intake is recommended due to the above-mentioned environmental conditions, as is avoiding alcohol while flying (8, 10, 18). Frequent sips of non-alcoholic and non-carbonated drinks; water (best), fruit juice, or carbohydrate-containing drinks based on individual energy/caloric.
One of the most common strategies people employ to support themselves in falling asleep is the use of alcohol. But does alcohol help us to relax and fall asleep? Along with caffeine, it is one of the most widely consumed psychoactive drugs today. Alcohol has been shown, even at low doses (1-2 drinks), to reduce sleep onset, which may explain why people take it to fall asleep. This may be viewed as a positive. However, sleep has several negative impacts once a person has fallen asleep. In the first half of the sleep period, it increases the time to get to Rapid Eye Movement (REM), increases awakenings and reduces stage 3 Non-Rapid Eye Movement (NREM) sleep which is essential for physical recovery. In the second half, REM rebound, and frequent awakenings occur. In addition, It also increases snoring and other sleep-related breathing disorders (19). Whilst travelling and crossing numerous time zones, the additional consumption of alcohol may disrupt recovery and sleep and affect the retiming and synchronisation of the SCN, which is crucial for adaptation to a new time zone.
Action: It is advisable to avoid alcohol consumption during flights and immediately after flying whilst travel fatigue, and potential dehydration is possible.
Sleep-promoting hypnotics (or sleep medications) should be considered for situations with opportunities to sleep. However, the opportunities occur under circumstances unsuitable for restorative sleep, such as flying. Trying to sleep when travelling on a plane causes inappropriate sleep timings (i.e., between 0800 and 1200 or between 1600 and 2000 according to the body clock), an uncomfortable environment (i.e., hot, cold, noisy, brightly lit), and/or in the presence of high levels of stress and anxiety. These environmental conditions are unlikely sufficient to achieve quantity or quality sleep.
However, studies have shown that prescription hypnotics such as temazepam, zolpidem, eszopiclone, and zaleplon generally are effective for inducing and/or maintaining sleep even under less-than-optimal circumstances (20-22). However, these medications should be used with caution as they can have lingering effects (e.g., drowsiness) and have been shown to interfere with natural sleep architecture (23). Additionally, they will not stop the occurrence of jet lag, and sleepiness due to jet lag will often still occur if there hasn’t been a circadian adjustment to the new time zone.
Action: If the aim is to sleep while travelling, i.e., it is night-time at your destination, then sleeping pills may facilitate sleep as conditions may not allow for rest to occur naturally. Suppose you have trouble sleeping whilst travelling or initiating sleep at your destination. In that case, prescription hypnotics such as temazepam, zolpidem, eszopiclone, and zaleplon are generally effective for sleep.
Jet lag can often lead to gastrointestinal disturbances exacerbated by dehydration, lack of movement, and changes to the type and volume of food intake during travel. Therefore, it has been recommended that foods high in fibre with natural laxative properties (e.g., prunes, kiwifruit, or chia seeds) should be consumed during travel (10, 18).
Action: Consuming these foods won’t reduce jet lag but may alleviate gastrointestinal disturbances, an often-inconvenient symptom of jet lag. Additionally, foods high in carbohydrates can promote drowsiness and, if timed appropriately, may assist with promoting sleep. However, caution should be taken if you have any pre-existing issues regarding irritable bowel syndrome, Crohn’s etc.
Alertness-promoting drugs (e.g., modafinil)
Modafinil and armodafinil are often used to treat excessive daytime sleepiness associated with jet lag (24). Both medications promote alertness maintenance when sleep and circadian factors threaten performance (25). They also both have beneficial effects on measures of alertness and cognitive performance. Due to these and other positive results, alertness-promoting drugs such as modafinil have gained popularity in enhancing the alertness of tired individuals experiencing jet lag following travel.
Action: However, whilst these drugs can improve alertness and performance, they do not return them to normal levels while the underlying circadian misalignment (jet lag) persists. They may also negatively affect sleep if used at inappropriate times and/or doses. Therefore, they should only be used when necessary and are not a cure for jet lag.
In addition to the above interventions that may assist with travel fatigue and jet lag, the following sleep hygiene principles may support your sleep:
- Routine – get up & go to bed at the same time every day.
- Exercise daily & consume minimal caffeine; stop caffeine at 12:00 (noon)
- Deal with stress during the day/early evening
- Don’t go to bed hungry/thirsty.
- No caffeine, nicotine, alcohol or heavy exercise 3-4 hrs. before bed
- No screen time at least 1 hour before bed, and no light-emitting screens in the bedroom
- The bedroom is comfortable & inviting (temperature, quiet, dark)
- Avoid daytime naps >20 mins.
- Avoid work within 90 mins of bed.
- If awake after 20 mins, do something relaxing out of bed until you are sleepy.
Check out the healthy sleep tips from the Center for Sleep Science, University of Western Australia
We hope you enjoyed this extended article on supplements and nutrition for travel fatigue and jet lag. If you require support designing travel schedules for performance pre, during and post-travel, please contact us at firstname.lastname@example.org and explore the rest of our website for more information, seminars, blogs, podcasts and much more.
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