Dealing with jet lag

Introduction

The challenge for jet setters

If you travel across three or more timezones on a regular basis, the chances are that you're all too familiar with the effects of jet lag.

It can be hard to escape; former US President George W. Bush famously blamed jet lag when he repeatedly attempted to escape a Beijing press conference through a locked door. (Jet lag may have been to blame when he vomited on the Japanese Prime Minister and fainted on a state visit, but that's another story.)

We all have a built-in body clock, which is adapted for action during the day and rest at night, on a 24-hour cycle. Sudden changes in timezone mean that we behave out of sync with what our bodies expect. Jet lag is the result of the body's internal rhythms being out of step with environment. The obvious effects are being too alert at night and sleepy during the day, but they go much further…

• Irritability, headache, general misery
• Memory and concentration lapses, disorientation, unable to sleep
• Slow reaction time, tremors
• Hunger pangs or appetite loss, gurgling stomach or butterflies
• Diarrhea & vomiting, constipation
• Fatigue, muscle aches & pains, changes of temperature
• Getting up frequently during the night

As a rule of thumb, when you fly across more than five zones, it can take 4 to 6 days to naturally shift the body clock so that it is in sync with your new environment.

Even if you're not flying across timezones, early starts, late nights, sitting for long periods in cramped spaces, lack of exercise and night flights can all contribute to travel fatigue. The dry cabin air on long flights (5-15% humidity) can also cause mild dehydration, which can make jet lag worse.

Regular travellers have irregular daily routines which can make it hard for the body to wind down in readiness for sleep. Very early flights can also lead to broken sleep, as we anticipate the early morning alarm.

In this guide we cover some practical steps to help your body adapt more quickly, common questions, and a bit about the science of jet lag

Prepare your runway: plan before you pack

If you're flying in for an important meeting or event, prioritize sleep when you're booking your flight times:

• avoid skimping on sleep to be at the airport at dawn;
• if you usually struggle to sleep on a flight, avoid flying overnight;
• if possible, arrive at your destination in time for a full night's sleep.

If you can influence the scheduling of your meeting, choose a time when you'd be awake at your point of departure, so that your internal body clock will be more alert. If you've flown west, meet in the morning, and if you've flown east, in the afternoon.

Choose a seat away from busy areas, if possible with extra legroom. Free websites like seatguru.com and seatplans.com list ratings of different seats on each plane for comfort and noise.

Before you fly across 5 or more time zones, start to gradually transition your body clock four or five days before you leave…

• Flying east? Start eating dinner, going to bed and setting your alarm an hour earlier each day
• Flying west? Eat dinner, go to bed and wake up later.

You'll recover from sleep loss more quickly if you're well rested before you fly. If you start with a sleep debt, it could make you more prone to jet lag.

Flying high: on the day of travel

• Take an on-flight bag with a few creature comforts…an eyemask, earplugs, moisturizer, lip balm, socks, spare clothes, chewy sweets for equalizing ear pressure and noise cancelling headphones can all come in handy.
• Wear loose fitting, comfortable clothing and shoes you can easily remove.
• You'll be able to relax more if you're not anxious about timings – leave plenty of time for navigating airport security.
• Drink plenty of water or fruit juice (rather than tea or coffee) to avoid dehydration. Alcohol will exacerbate dehydration and make sleep more fragmented and less restorative.
• To help adjust the body clock, change your watch and phone to the time at your new destination when you board. Plan to eat and sleep according to your new schedule, not the one imposed by the in-flight service.
• Have a plan for how you'll be getting from the arrival airport to your final destination.

Destination daylight: on arrival

Follow the sleep-wake and meal times of your local destination, as far as possible. Sunlight acts as a strong stimulant to promote alertness, while darkness switches on melatonin, the body's pro-sleep hormone.

• After a westward flight, stay awake while it's daylight and only try to sleep when it gets dark.
• After an eastward flight, stay awake but avoid bright light in the morning, and be outdoors as much as possible in the afternoon.

If you've arrived during the day and you really can't keep your eyes open:

• A jog or a walk will raise endorphin levels and suppress drowsiness.
• Take a brief nap – up to 40 minutes – enough to reduce sleepiness, but brief enough not to disrupt your nighttime sleep drive.

If you're staying at a hotel, order a wake up call in the morning, and even if you're taking a nap. You're more likely to sleep through your alarm if you're sleep deprived, because you'll be more likely to drift into very deep sleep.

If you have a regular wind down routine at home, maintain it while you're away. Take a favorite pair of PJs or a pillow – familiar objects will make your new hotel room feel more comfortable.

If you're in bed struggling to get to sleep, try these relaxation techniques:

• Imagery: When you're in an unfamiliar bed, with unfamiliar sounds, picturing your favorite scene before you sleep can really help. The secret is to practice the same scene and sequence in advance, so that you can replay it easily in your mind.
• Paradoxical thinking: One of the problems with jet setting is that you're aware that you're short of sleep and you try too hard to get to sleep. Use reverse psychology: tell yourself to try and stay awake. By telling yourself it's OK to remain quietly wakeful, the chances are you'll relax into sleep.

Common questions

Is it worth trying to adjust the body clock if I'm only away for a few days?

It depends on what your plans are while you're away. If you're only one or two time zones from home, you might manage maintain your usual schedule, provided that you arrange important meetings at times you're usually alert.

Does everyone suffer from jet lag?

The risk and severity of jet lag increase with the number of time zones you cross. More than three hours of time difference are usually required to trigger a problem. Older adults often experience worse symptoms than younger adults. Young children have less developed daily rhythms; babies under the age of 3 don't seem to be affected by jet lag at all.

Is it worse flying east or west?

Travelling eastward typically causes worse disruption than travelling in a westward direction. This is because most people find it harder to shorten than to lengthen their natural daily cycle.

Should I take melatonin?

Melatonin is a natural hormone that helps to get the body ready for sleep. It is produced by the brain's pineal gland in response to darkness. In the US, synthetic melatonin is sold as a nutritional supplement and advertised to help regulate sleep-wake cycles.

In a recent review of jet lag trials, most studies found that melatonin was more helpful than a placebo for reducing self-reported sleepiness, but the effects were modest (Costello et al 2014). There were no serious side effects from short term use, but one trial did note an increase in morning sleepiness.

In the EU, it is classified as a medicinal product, and is only legally available on prescription from a doctor. Similarly melatonin is not available over the counter in Australia, Greece, New Zealand, Brazil, South Africa, Iceland.

Should I take sleeping pills?

Sleeping pills, or hypnotics, can help some people get to sleep, and to stay asleep, but they won't help the other aspects of jet lag (aligning the body clock to the new timezone). Hypnotics are also associated with side effects, including headache, dizziness, nausea, confusion, and amnesia, which may outweigh any short-term benefits.

The science of jet lag

Activity in every cell in our bodies follows a daily 24 hour rhythm or circadian cycle, which is governed by a master 'body clock' in the brain. This clock regulates our patterns of sleep, eating, alertness, body temperature, growth and many other biological functions.

The body clock adjusts our daily cycles based on external cues, known as Zeitgebers (meaning “time-givers”), of which daylight is the most important. For example, when it gets dark in the evening, the body clock increases the production of melatonin, a hormone which causes drowsiness and lowers body temperature. Levels remain high during sleep but taper off in response to light.

Jet lag arises when we expect our body to perform activities at times when it's prepared for rest or recovery, or when we try to sleep when the body clock is sending cues to drive alertness.

Some of the unpleasant symptoms of jet lag are due to fatigue. When we're sleep deprived, we can trigger two opposing systems – the parasympathetic nervous system and the sympathetic nervous system. The sympathetic nervous system drives the flight or fight response, which throws the body into high stress alert mode. The parasympathetic nervous system controls at-rest functions like digestion. Your symptoms will depend on which system reacts the most.

To reduce jet lag, we can actively manage the timing of exposure to Zeitgebers such as daylight, darkness and mealtimes to help adjust to a new time zone, and make time for good quality sleep.

References

Costello RB et al. (2014) The effectiveness of melatonin for promoting healthy sleep: a rapid evidence assessment of the literature Nutrition Journal 13:106

Herxheimer A (2014) Jet lag BMJ Clinical Evidence Apr 29;2014 pii:2303

Herxheimer A & Petrie KJ (2009) Melatonin for the prevention and treatment of jet lag Cochrane Database of Systematic Reviews Issue 3. Art. No.CD001520

Mass, James B (1998) Power Sleep Villard, New York

Thibeault C & Evans AD (2015) ASMA Medical Guidelines for Air Travel: stresses of flight Aerospace Medicine and Human Performance 86(5)486-487