Avoid the jet lag slump

Are you jetting off somewhere nice this Christmas or New Year? Lucky you if you are. Many of us long to get away from it all at this time of year and want to maximise our enjoyment at the new locale. For many, though, symptoms of jet lag can make you feel fatigued, out of sorts or even have digestive disturbances. But you don't have to suffer... there are ways of helping you to minimise the symptoms, so that you can maximise your enjoyment.

What is jet lag?

Jet lag refers to a range of symptoms that can occur when travelling across different times zones, as a result of your body not adapting quickly enough to a different light-dark schedule of a new time zone. It is caused by a temporary mismatch between your internal body clock (called your circadian rhythm) and the external light-dark cycle (1). 

What are the symptoms?

The disruption occurs to the sleep-wake cycle, so it primarily manifests as a sleep disorder. But other symptoms can be experienced as well. These include fatigue, decreased alertness, reduced mental capacity, co-ordination problems, gastrointestinal disruption and loss of appetite (2). Often, symptoms can be exacerbated by the effects of sleep-loss, which usually accompanies long-distance travel.

What is your body clock?

It is a biological process that displays a repeat rhythm over about 24 hours, such as the sleep-wake cycle. We have many internal body clocks but the master clock is your sleep-wake cycle. And this is governed by the action of light falling on the retina of your eyes, that provides the clock with information as to whether it is night or day. In response to darkness, the hormone melatonin (which promotes sleep) is produced. Secretion peaks at night and ebbs during the day. Its rhythm is linked with and contrasts with that of cortisol (the hormone that gets you up in the morning and keeps you active), which peaks in the morning and ebbs in the evening. Both melatonin and cortisol secretion rhythms are directly regulated by the master clock (3). Together, they stabilise this natural rhythm (4).

How can the body clock be disrupted?

Any external stimuli that affects melatonin and cortisol secretion will also impact the master clock. Only retinal light exposure can affect melatonin synthesis (5). However, cortisol production can be influenced by other factors, not just the master clock (6). Being highly stress-responsive, cortisol's natural rhythm can be disrupted by any stressful situation, including jet lag (7). Such disruption to the two main clock regulatory hormones can lead to 'out-of-sync' rhythms in biological processes, resulting in an array of symptoms (8).

How can a nutritionist help?

Nutritionists use their extensive knowledge of anatomy and physiology, to advise on nutrition support and lifestyle measures that can be employed to prevent or minimise disruption to your natural body processes. Using an individualised approach, they can tailor a plan to suit your schedule. Frequent fliers, in particular, may need specialised help in regulating their body processes. 

Top tips:

  • Light is the key factor in advancing or delaying your circadian rhythm (9), so your focus should be on manipulating your light exposure.
  • Opt for overnight flights - you'll have dinner at the normal time and will be much more likely to sleep than on an afternoon flight. Depending upon the number of time zones that you cross, you'll arrive at your destination during daylight. Make sure you then get outside into daylight for the light to re-set your clock.
  • Wear a sleep mask during the flight - avoid the plane cabin lights during the flight as they will prevent your sleep hormone, melatonin, from being produced. And so you won't sleep. Try and get as much sleep as possible on the flight.
  • Avoid alcohol and coffee - before and during the flight. They will both activate cortisol causing you to be more awake and will leave you feeling dehydrated.
  • Stay hydrated - drink at least 250ml for every hour that you are in the air, even if you don't feel thirsty. That is the equivalent of half a small bottle of water. The cabin air is very dehydrating...and dehydration is a stressor on the body that will activate cortisol, which will keep you awake.
  • Get outside upon arrival - you want to expose yourself to as much sunlight as you can to re-set your clock to the new time zone.
  • Don't drift off too early at your new destination - try and wait until it becomes dark before you sleep. Just wait until darkness falls, even if that is earlier than your normal bedtime and then go to sleep. Do ensure that you use a sleep mask on the first night to ensure that your body can sleep as long as it needs to, without being awoken by any light.
  • Wake up naturally the next day - try not to force yourself to get up at a certain time the next morning by setting an alarm. Let your body take all the rest it needs and allow yourself to wake up naturally.
  • Repeat the above for the return flight.


(1), (3), (4), (7), (8)  Tsang A et al (2014). Interactions between endocrine and circadian systems.  Review.  Journal of Molecular Endocrinology, 52: R1-R16.(2)  Waterhouse J et al (2005). Further assessments of the relationship between jetlag and some of its symptoms.  Chronobiology International, 22: 121-136.(5), (6)  Rea M S (2012).  Relationship of morning cortisol to circadian phase and rising time in young adults with delayed sleep time.  International Journal of Endocrinology, Art AD: 749460.(9)  Figueiro M G et al (2006).  Does architectural lighting contribute to breast cancer?  J Carcingo, 5: 20.

The views expressed in this article are those of the author. All articles published on Nutritionist Resource are reviewed by our editorial team.

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Written by Jan Clementson, Registered Nutritionist BSc (Hons) | mBANT | CNHC
London SW18

Jan Clementson is a nutritional therapist with a first-class honours degree in nutritional medicine. She specialises in energy and stress-related disorders at her Boundless Energy Practice and is the author of the book: The Energy Solution. Previously, she was a clinical nutrition advisor at BioCare and a lecturer in BioMedicine for London CNM.

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