1. Your body has a natural circadian rhythm, an internal biological clock which regulates sleep, eating patterns, mood, hormone regulation, and everything your body does during the day.
2. Jet lag is a misalignment between this internal clock and external cues, such as light exposure. This can lead to reduced alertness, nighttime insomnia, loss of appetite, depressed mood, poor balance and coordination, gastrointestinal upset, fatigue, cloudy thinking, and decreased physical and mental performance.
3. Fortunately, there are several tricks of the trade we will share with you to help combat jet lag and live your best life!
Jet lag, also known as flight dysrhythmia, may be characterized by an entire list of unpleasant symptoms: reduced alertness, nighttime insomnia, loss of appetite, depressed mood, poor psychomotor coordination, gastrointestinal disturbances, fatigue, reduced cognitive skills, and decreased physical as well as mental performance are well documented examples. The more time zones you cross, the worse your jet lag is likely to be.
Rapid travel across multiple time zones causes a temporary misalignment between biological rhythms and external cues known as zeitgebers, or time givers. Jet lag is essentially caused by a desynchronization between our endogenous circadian clock, which regulates important biological rhythms, and exogenous cues, including geophysical variations like the light/dark cycles in solar days. Simply put, jet lag throws our internal rhythms out of synchrony with our external environment, leaving us with numerous unpleasant symptoms.
The culprits of this desynchrozation lie in the brain – specifically the hypothalamus – and are known as the suprachiasmic nuclei (SN). These nuclei regulate circadian oscillators by using visual information sent from the retina, which is why external cues including light and dark cycles are so important. Information regarding physical activity and general excitement is also sent to the nuclei. Collectively, these cues set genes throughout the body, known as ‘clock genes,’ to 24h time. The pathways involved here essentially act to translate external cues into biological rhythms that form our internal concept of time. Without external regulation, our clock genes operate on 24.5h time. The SN also help regulate the secretion of hormones including serotonin, melatonin and cortisol; their job is to help regulate things like our sleep cycles, eating patterns, and cognitive function in concert with the clock genes.
Ideally, in a body that is adjusted to its local time zone, the body’s circadian rhythms behave as follows:
- Melatonin secretion peaks at night, and decreases throughout the day
- Cortisol levels peak in the morning, and decrease throughout the day
- Core body temperature reaches its lowest peak in the middle of the night and rises throughout the day
- Clock genes promote activity in the daytime and recovery during the night.
In a jet-lagged body, these rhythms get mixed up because the external environment has changed and the internal rhythms haven’t had a chance to catch up. Rises in core temperature at night will cause pre mature wakening; melatonin secretion throughout the day will cause daytime sleepiness, and lack of sleep is responsible for a large handful of common jet lag symptoms.
Jet lag doesn’t just make you feel awful; it hangs around, sometimes for weeks. Our bodies adjust to new time zones at a sluggish rate of 1.5h per day after westward flights, and 1h per day after eastward flights. In simple terms, the hourly difference between point A and point B during travel translates into the days required for recovery. Eastward travel generally causes difficulty in falling asleep due to phase advances (your body is behind the local time zone) while westward travel interferes with sleep maintenance due to phase delays (your body is ahead of the local time zone).
Jet lag can also be made worse by travel fatigue and the general difficulties and stresses associated with long trips. Sources of travel fatigue include cramped environments that don’t offer much opportunity for exercise, restricted food choices, dehydration due to dry cabin air and cabin hypoxia, and disruption of sleep and routine. Travel fatigue has less to do with time zone transition and more to do with the effects of travelling itself. The good news is that the effects of both travel fatigue and jet lag can be lessened using a few simple tricks.
1. Tackle your travel fatigue
Before your trip:
- Ensure the trip is planned
- Anticipate layovers, and arrange for them to be as easy as possible
- Arrange documentation, passports, visas etc. beforehand
- Ensure arrangements have been made at your destination
During your trip:
- Bring some snacks (apples, nuts, carrots, whole grain crackers are great)
- Make sure you’re drinking water (rather than tea, coffee or alcohol)
- Try to avoid sleeping if you’re travelling to substantially new time zones, even though it might seem like a good idea. Jet lag symptoms may be worsened by anchoring sleep patterns to your old time zone
Once you’ve reached your destination:
- Rehydrate with non-alcoholic drinks
- Take a warm shower; try avoiding hot showers and baths
- Take a brief nap if needed, but not long enough to disrupt sleeping at night
2. Grab a bottle of melatonin
Research shows that melatonin can be an exceptionally helpful tool in overcoming jet lag by helping regulate the circadian system. Melatonin acts on the body’s clock genes by means of the SN (the culprits of desynchronization that live in the hypothalamus) and promotes sleep, an elusive concept for frequent travelers. The administration of 0.5-5mg of melatonin 2-3 before local bedtime has been shown to help resynchronize circadian oscillators while improving nocturnal sleep and alertness during the day. Generally speaking, sleep is normally initiated during the falling phase of bodily temperature rhythms and the rising phase of melatonin secretion, meaning our core body temperature is coldest in the middle of the night and our melatonin levels are highest in the late evening. This means that melatonin administration in the afternoon and evening causes phase advance (you get tired sooner), while administration in the late night or early morning causes phase delay (you get tired later). Melatonin produces optimal results when taken 3 days prior to departure 2-3 hours before destination time zone bedtime, and 4 days following departure, also a bit before destination time zone bedtime.
3. Structure your caffeine consumption
While jet lag can make it very difficult to fall asleep according to the local time, it can be almost as difficult to stay awake during the day. Stimulants, namely caffeine, have been suggested to alleviate daytime sleepiness, and have shown positive effects in circadian resynchronization when used in combination with melatonin. Both fast and slow-release forms of caffeine may help counteract daytime sleepiness and nighttime insomnia – tossing a thermos or mug full of green tea in your travel bag for sipping throughout the day may prove helpful in alleviating jet-lag induced sleepiness and resulting symptomology.
4. Time your light exposure
Light exposure unassumingly plays a massive role in the synchronization of our biological rhythms to external time by means of altering clock genes. Research indicates that critically timed light exposure of sufficient intensity may help mitigate jet lag symptoms and speed up circadian synchronization. More specifically, light exposure during or near minimum core temperature produces the greatest phase shifts. Delays of 2.5-3 hours per day and advances of 1.5-2 hours per day have been observed using critically time light exposure.
How does it work?
Light exposure at your lowest body core temperature (usually the middle of the night at home) and light avoidance at your highest core temperature (usually mid day at home) serves to essentially stop your circadian oscillator (this is where melatonin and external factors may come into play to help resynchronize your biological rhythms to new time zones). Light exposure will also inhibit the release of melatonin, which is why we get sleepy in the evening when the sun goes down; these biological rhythms operate in concert. For this reason, exposure to bright light coupled with melatonin used has been effectively shown to alleviate jet lag by synching our bodies to destination time faster.
How do I time my light exposure?
Light exposure in the morning will advance your circadian rhythms (you’ll sleep earlier), while light exposure in the evening will delay them (you’ll sleep later).
If you are travelling eastward, try advancing your sleep time by one hour per night 3 days prior to travel, and expose yourself to bright light upon rising. Upon reaching your destination, it is suggested that you advance your rhythms by exposing yourself to morning and afternoon light and avoiding evening light at your destination. Advance the time that you expose yourself to bright light by one hour per day at your destination to continue fostering adjustment throughout your trip.
If you are travelling westward, try delaying your sleep time by one hour per night 3 days prior to travel. Upon reaching your destination, it is suggested that you delay your rhythms by exposing yourself to evening light and avoiding exposure in the early morning.
5. Make time for physical activity
Exercise has been shown to be helpful in mitigating the negative effects of jet lag. Physical activity of any sort that coincides with bring light exposure (ideally daylight) is a zeitgeber (or time giver), meaning it is an external factor capable of regulating internal rhythms. Working up a light sweat around 2-3am by the standard of your home time zone might actually be helpful - current studies suggest gentle exercise at your lowest core temperature (typically the middle of the night) in a new time zone may be effective in synchronizing your internal rhythms to the local time faster.
6. Consider the length of stay
Our body clocks aren’t easily disrupted by external factors, preserving our biological rhythms even in the face of daytime naps or waking throughout the night. However, it is exactly this resistance to perturbation that makes it so difficult for our bodies to adjust to new time zones. In other words, our clock genes have substantial inertia that we have not yet found a foolproof way of manipulating. For this reason, it is important to consider the length of stay when travelling to a destination. An adjustment of activities to the timing of home may be more appropriate for travel lasting only several days as opposed to attempting to retrain the circadian oscillator twice.