Summer is almost here and that means holidays and travel! We’re sure you are thinking of the fun times and adventures… but first you have to survive the flight and overcome jet-lag. Hop on board and join us for some nutrition tips and tricks to ease the transition to a new time zone and start enjoying your holiday sooner.
The Body’s Clock
Your body has a natural rhythm – “circadian rhythm” – that is centered around a roughly 24-hour day. The suprachiasmatic nuclei in the brain act as the master clock and orchestrates physiological functions including: muscle contractions, glucose metabolism, body temperature, and digestive abilities to match the typical activities that occur during the day and night (Johnston et al.). A variety of internal signals and environmental factors called “zeitgebers” help the suprachiasmatic nuclei synchronize the circadian rhythm with the environment. One of the most powerful signals is daylight, and to a lesser degree artificial light.
It is believed that light inhibits melatonin – you’ll feel more awake because melatonin is a hormone that makes you sleepy. Conversely, a lack of light will encourage melatonin release, making you feel more sleepy. The suprachiasmatic clock picks up melatonin’s signal and starts preparing the body for sleep if levels are high or alertness if levels are low. Temperature, physical activity, eating and drinking patterns, and social factors also regulate your body’s rhythm (Reilly et al).
Jet-lag is a common term for the desynchronization of the body’s internal clock with the environment that occurs when travelers cross different time zones; technically classified as a “circadian rhythm sleep disorder” (Forbes-Robertson et al.). The symptoms are due to the fact that our diurnal (sleep and wake activities) become out of sync with our body’s circadian rhythm. Our circadian rhythm will adjust to the new location but this takes time – approximately 1/2 day per hour of time difference going west and 1 day per hour of time going east (Forbes-Robertson et al).
Symptoms of Jet Lag
- sleep disruption or poor sleep
- day-time fatigue
- impaired mental performance and mood
- loss of appetite
- poor physical performance (Forbes-Robertson et al.)
Jet Lag and Digestion
Your digestive system is in tune with your body’s natural rhythms and prepares for a meal based on the circadian rhythm (Johnston et al.). For example, you tend to digest food more slowly at night and have a reduced blood flow, delaying the absorption of nutrients. If you eat a large meal before bed (or what your body thinks is bedtime) it could disrupt your sleep because it will take that much longer to digest. Cortisol (stress hormone) promotes digestion and is also affected by the body’s clock (Reilly et al.). Consequently, changing time zones may affect your appetite and the amounts of food you eat.
Coping with Jet Lag
First things first, it is generally thought to be easier to adjust to changing time zones when you
are heading west (delaying the body’s rhythms) as opposed to traveling east (speeding up the body’s rhythms). When it comes to coping with jet-lag we recommend trying to change your behaviours rather than relying on a slew of pills.
The first strategy you can use is to start adjusting before you leave. Shift your schedule by 30 to 60 minutes each day a couple days before departure – this means your meal times, as well as time-to-bed and time-to-rise and other environmental cues. Realistically, though this is often impractical, especially if the new time zone is extremely different and you have to deal with the day-to-day of going to work, etc. (Reilly et al.)
The Argonne diet, alternating days feeding on high protein foods with fasting on small amounts of low carbohydrate has been suggested but its effectiveness is unclear and again you are faced with logistics (Forbes-Robertson et al.). At this point there is no conclusive evidence to show if and how adjusting the ratios of carbohydrates, proteins and fats can help with jet-lag.
Nutrition During the Flight
Meals: While in the air, you are somewhat at the mercy of the airline with respect to meal timing and choice of foods. The first strategy is to pack your own snacks (within the limitations of what you can get through security and customs). Next is to switch your meal times to those of your destination. You may not feel like eating because your internal clock doesn’t think it’s time but try anyway. Same goes for resting – even if you can’t sleep try to rest quietly (no screens – save the on-flight movies for “daytime”).
- Roasted chickpeas
- Edamame dry roasted
- Hummus (small individual packets)
- Protein bars
- Crackers (quinoa, pulses)
- Dried fruit or fruit bars
- Granola or cereal bars
- Rice cakes
- Pretzels (unsalted)
- Sports bars
Hydration: Planes are constantly filtering and recirculating the air, which creates a dry environment increasing dehydration. Furthermore, many people limit their fluid intakes to avoid using the bathroom on the plane (guilty as charged!). We admit that the washrooms are cramped and sometimes bumpy and it’s unpleasant to wake people up and crawl over seats to go pee but dehydration is going to make your jet-lag worse.
Start out by being well hydrated before you leave. Carry an empty (to get through security) water bottle that you can fill-up and drink throughout the flight – about a 1/4 cup more than normal per hour should be enough (Reilly et al.). Try to avoid excessive caffeine, alcohol, sugar (colas and other sweetened beverages), and salt (so much for the airline pretzels!). Finally, as with your meals, shift your drinking pattern to the local schedule; avoid drinking at “night” so you can get the best sleep possible and drink more during the “day”.
When You Arrive
Work on switching to the local schedule. Light is the most potent factor and in the early evening and first part of your home “night”, light exposure will delay your cycle; whereas, light in the 2nd part of your home “night” and early morning light will advance your cycle (Forbes-Robertson et al.); for more detailed information you can check out Serkh et al. During the “day” get some light exercise in the sunshine – walk around and see the sights! The sunlight and the exercise will help reset your internal clock more quickly. Make use of the other environmental cues such as eating and being social to help your brain and body adjust (Reilly et al.). Try to eat a good breakfast and limit eating late at night, especially slow-to-digest, high-fat foods.
Take in a few more fluids as chances are you got a bit dehydrated on the way (especially if you’ve opted to go somewhere sunny and warm). Caffeine can be a useful strategy or a complete disaster depending on how you use it (Pierard et al.; Ker et al.). Certainly, it acts as a stimulant and can help wake you up but too much can increase anxiety, stress (and don’t fool yourself travel can be stressful – lost, hungry, tired, culture shock), dehydration, and further disrupt your sleep schedule. Know that it takes at least 30 minutes for that cup of coffee to kick in and it has a half-life of 5-7 hours (half of the amount you consume has been metabolized in that amount of time), so time your caffeine well and use sparingly (Webmd).
Finally, knowing something about the culture, foods, and food safety standards of your destination can help you avoid illness and generally make everything more enjoyable.
Happy holidays and safe travels!