A thrombosis is a blood clot. The clot may block a blood vessel, causing potentially serious health effects. A deep vein thrombosis (DVT), is a blood clot that forms in the deep veins of the leg. A deep vein thrombosis in the thigh carries a risk of pulmonary embolism. This occurs when the clot, or thrombus, loses its attachment to the inside of the vein, leaves the leg and lodges in the pulmonary artery, the main blood vessel to the lungs. If the clot is large enough, it can completely block that artery and cause death.

Blood flow through the leg veins generally requires some mechanical help, since it 'flows' up instead of down. Working calf muscles act as a pump. The contracting muscles compress the veins and force the blood in these veins upwards to the heart. This process is aided by valves in the veins, which direct the flow of blood and counteract the effects of gravity.

Sitting still for long periods of time allows blood to pool in the veins. There is debate over whether or not the confinement of long distance international flights may contribute to the risk of DVT. This condition is known as 'economy class syndrome'.

Symptoms
The symptoms of a deep vein thrombosis (DVT) may include:

WEARING tights on long-haul flights relieves ankle swelling and helps ward off post-flight fatigue, a study of pilots and passengers has found.

The uncomfortable condition, called ankle oedema, is caused by a build-up of fluid.

Lower-leg socks are known to relieve the problem, but exercise physiologist Stephen Lambert wanted to see whether the graduated compression tights used to help athletes recover from strenuous competition could also help.

About 60 Qantas pilots and passengers were enlisted to test the hosiery, wearing it on one leg of a trip and flying tights-free on the return leg.

The study, funded by a tights manufacturer, is published in the latest Medical Journal of Australia.

"When subjects wore the (tights) they had a 60 per cent improvement in their leg pain rating at the end of the flight, a 50 per cent improvement in their leg discomfort rating and a 45 per cent improvement in their leg swelling rating," said Dr Lambert, from Westmead Hospital in Sydney.

"There was also an 18 per cent improvement in their energy level rating, a 13 per cent improvement in their alertness level and a 12 per cent improvement in their ability to concentrate."

He said the tights may be particularly useful for flight attendants who need to remain alert and active throughout a flight.

More studies are underway to investigate whether tights could be more effective than the standard issue knee-high compression socks.

A randomised crossover study of low-ankle-pressure graduated-compression tights in reducing flight-induced ankle oedema - link

Melissa J Hagan and Stephen M Lambert

MJA 2008; 188 (2): 81-84

Abstract

Objective:

To determine if low-ankle-pressure graduated-compression tights (GCTs) reduce flight-induced ankle oedema and subjectively rated travel symptoms of leg pain, discomfort and swelling, and improve energy levels, ability to concentrate, alertness, and post-flight sleep.

Design, setting and participants:

Open, randomised crossover trial comparing the effects of GCTs (5 mmHg at ankle, 17–20 mmHg at calf and falling to 10 mmHg above knee and 4 mmHg at buttocks) among 50 adults on flights of 5 hours’ or more duration between 1 May and 8 October 2006; 47 volunteers (pilots and passengers) completed the trial.

Main outcome measures:

Differences in right ankle circumference before and after flight with GCTs and without GCTs; travel symptoms rated on visual analogue scales.

Results:

Low-ankle-pressure GCTs decreased ankle swelling (mean difference, − 0.19 cm; 95% CI, − 0.33 to − 0.65 cm; P = 0.012). Participants reported their legs felt better (mean, 1.6; P < 0.001; 95% CI, 1.0 to 2.1), warmer (mean, − 1.1; P < 0.001; 95% CI, − 1.6 to − 0.6), and they had a better night’s sleep (mean, 1.2; P < 0.001; 95% CI, 0.8 to 1.7) after the flight when they wore GCTs. Shifts in rating-scale probability distributions showed improvements in the ratings of pain (60%; P < 0.001), leg discomfort (50%; P = 0.001), leg swelling (45%; P = 0.006), energy levels (18%; P = 0.016), alertness levels (13%; P = 0.031), and concentration (12%; P = 0.023) when wearing GCTs.

Conclusions:

Low-ankle-pressure GCTs reduce flight-induced ankle oedema and subjectively rated travel symptoms of leg pain, discomfort and swelling, and improve energy levels, ability to concentrate, alertness, and post-flight sleep.

Trial registration:

Australian New Zealand Clinical Trials Registry ACTRN12606000150549.

More than 90% of air passengers flying for more than 5 hours will develop some degree of ankle oedema.1 Use of low-compression hosiery (8–20 mmHg at the ankle) reduces subjectively rated flight-related symptoms of discomfort, swelling, fatigue, aching and tightness.2 However, the bulk of published research on flight-induced oedema results from studies that measure oedema with the incidence of symptomless deep vein thrombosis (DVT). Passengers can expect a reduction of both oedema and DVT when wearing below-knee compression stockings with ankle compression levels of 14–17 mmHg.3,4 The most recent Cochrane review on this subject suggests the need for further research on the relative effects of different pressures exerted by stockings.3 We initiated this trial because of the scarcity of reports on the effect of low-ankle-pressure graduated-compression tights (GCTs) on flight-induced ankle oedema and other flight-related symptoms.

The GCTs we used in our study comprised 76% nylon and Meryl microfibre, and 24% Roica spandex, and were developed by Australian sports physicians and sports scientists specifically to help athletes to recover more quickly from strenuous competition and training. They were full-leg-length gradient-compression stockings, similar (but with a lower compression) to antithrombosis stockings. The GCTs we used had the following pressures: about 5 mmHg at the ankle, 17–20 mmHg at the calf, and falling to 10 mmHg above the knee and 4 mmHg at the buttocks, compared with the frequently cited Scholl Flight Socks (SSL Australia Pty Ltd, Melbourne, Vic), which provide 14–17 mmHg of pressure at the ankle.4 GCTs promote blood flow from superficial veins into deep veins and compress deep veins.4-7

The purpose of our trial was to test the hypothesis that low-ankle-pressure, full-leg-length GCTs significantly improve flight-induced ankle oedema and other flight-related symptoms. We subjectively assessed not only leg pain, discomfort and swelling, but also energy levels, ability to concentrate, alertness, and post-flight sleep.

Methods

We conducted our unblinded, randomised crossover trial according to International Conference on Harmonisation of Technical Requirements for the Registration of Pharmaceuticals for Human Use/Guidelines for Good Clinical Practice (ICH GCP) standards,8 and the protocol was approved in advance by the Bellberry Human Research Ethics Committee.9 Each participant provided written informed consent before participating.

Participants were volunteers aged 18 years or older who had a confirmed flight booking on a flight of 5 or more hours’ continuous duration (with at least a 48-hour period between the forward and return flights) between 1 May and 8 October 2006. They included Qantas pilots referred by the Australian and International Pilots Association and general passengers who responded to advertisements in major metropolitan newspapers in Brisbane, or after being referred by other trial participants; volunteers were sought between 20 April 2006 and 16 September 2006. Volunteers were not eligible if they had received medical advice to wear GCTs in flight; had a previous history of DVT; had been prescribed medication for cardiovascular disease, coagulation disorders, varicose veins, bone or joint problems, diabetes or hypertension; had a body mass index (BMI) ≥ 35; or if they had had neoplastic disease within the previous 2 years (other than basal cell carcinomas). Thus, participants had a low to medium risk of DVT, and our study had the same inclusion and exclusion criteria as the LONFLIT 4 study.4

The GCT used was a Skins travel and recovery garment (Skins Compression Garments Pty Ltd, Sydney, NSW), listed on the Australian Register of Therapeutic Goods as a Class 1 medical device (ID: 80116). Participants were randomly assigned to wear low-ankle-pressure GCTs on either their forward or return flight. Random allocation was achieved by giving participants a sealed envelope with instructions according to a computer-generated randomisation sequence.10 During the control flight (when GCTs were not worn) participants wore their usual clothes.

Suggestions for in-flight exercises were given to both groups. The exercises were described on an instruction sheet,11 and included mild (mainly isometric) exercises and walking about the cabin and moving the legs for 3–4 minutes every hour.

Outcomes were self-reported. Participants were given oral and written instructions on how to measure around their ankle and how to complete the study questionnaire. They measured around the smallest part of their right ankle, marking three points on the ankle using a 150 cm plastic tape measure. They were instructed to take measurements in the airport waiting lounge (before take-off), 2.5 hours into the flight, and on landing (while on the tarmac), and were asked to take three measurements at each time.

The primary endpoint was the difference in change of ankle circumference (measurements taken before flight and after landing) between the control group (no GCTs) and treatment group (GCTs).

Secondary endpoints included leg pain, leg discomfort, perceived leg swelling, energy levels, alertness, and ability to concentrate, each rated on a unidimensional, 11-point numerical rating scale (NRS). A bidirectional Likert scale (− 5 to + 5) was used to assess post-flight comparisons of sleep, comfort, coolness, and choice of future flight garment.

Adverse-event data were collected as a specific written question about the occurrence of events, and a review of any comments recorded on the questionnaire. When participants mailed back their data, we performed an additional follow-up, either by telephone or email, during which we again prompted them to report any adverse event.

Statistical analysis

The expected difference between the means of the ankle circumference for the GCT and control groups was about 0.2 cm.

The standard deviation of the difference was assumed to be 0.3 cm. The sample size required to detect a 0.2 cm difference in ankle size with 80% power and 5% significance was 38 participants.12 We estimated that 12 would drop out or be lost to follow-up, as the study was a self-assessment with no investigator visit. Thus, 50 participants were entered into the study.

All calculations were based on an intention-to-treat analysis. Ankle circumference differences were analysed using a crossover analysis of variance. The difference in means is given with appropriate P values and, where relevant, 95% confidence intervals.

The secondary endpoints involved ratings which were analysed using the non-parametric Wilcoxon matched-pairs signed rank test. We used InStat statistical software, version 3 (GraphPad Software, San Diego, Calif, USA). Count variables were analysed using a generalised linear model with a Poisson distribution and log link by means of GenStat for Windows (10th edition; VSN International, Hemel Hempstead, UK). A P value of less than 0.05 was used to indicate statistical significance.

Results

Sixty-seven people (23 Qantas pilots and 44 passengers) volunteered to participate in the study, and 17 (16 passengers and one pilot) were excluded (Box 1). Of the 50 participants (22 pilots and 28 passengers) recruited to the study, 26 wore GCTs on their outward flight (Group 1; 18 men and six women) and the remaining 24 wore GCTs on their return flight (Group 2; 17 men and six women). Ultimately, 47 participants (24 in Group 1 and 23 in Group 2) returned data and so completed the study (Box 1). Their ages ranged from 24 to 71 years.

Box 2 presents baseline characteristics for the participants in terms of physical characteristics, leg symptoms and activity level, and proportion of time at work spent sitting and standing. There is nothing in these data to suggest that our participants would not be representative of the general healthy flying population.

When wearing GCTs, there was a decrease in ankle swelling compared with not wearing GCTs (mean difference, − 0.19 cm; 95% CI, − 0.33 to − 0.065 cm; P = 0.012).

Measurements involving ratings were not analysed in a way that produced CIs of rating differences. Significant differences in Box 3 indicate a shift in the probability distributions of the ratings. So, for the rest of this section we make general observations on the ratings based on Box 3.

When subjects wore GCTs, they had a 60% improvement in their leg-pain rating at the end of the flight, a 50% improvement in their leg discomfort rating and a 45% improvement in their leg-swelling rating.

There was also an 18% improvement in their energy-level rating, a 13% improvement in their alertness level and a 12% improvement in their ability to concentrate.

At the end of both flights, participants responded to a number of additional questions using a bidirectional Likert scale (− 5 to + 5, with 0 representing no change). A t test was used to analyse the responses.

Participants reported their legs felt better after the flight (mean, 1.6; P < 0.001; 95% CI, 1.0 to 2.1), that they had a better night’s sleep after the flight (mean, 1.2; P < 0.001; 95% CI, 0.8 to 1.7), and that their legs felt warmer after the flight (mean, − 1.1; P < 0.001; 95% CI, − 1.6 to − 0.6) when they wore GCTs.

Participants reported improved comfort when wearing GCTs, but this did not reach statistical significance (mean, 0.6; P = 0.057). On the other hand, they would more than occasionally choose to wear GCTs on future flights (mean, 2.0; P < 0.001; 95% CI, 1.4 to 2.7).

The only adverse event reported was transient discomfort from the footstrap of the GCTs, reported by nine participants (19%).

Discussion

The use of GCTs to improve blood flow for patients with chronic venous insufficiency is routine. The rationale is based on the observation that oedema is the first symptom when venous blood flow is not adequately maintained and that compression stockings increase blood velocity by mechanically reducing the size of the larger veins. In addition to this, they also increase perivascular pressure and inhibit the outflow of blood and plasma factors from the endothelial venular gaps. This reduces contact with tissue factors and subsequent coagulation and thrombosis formation.13

Importantly, the 2006 Cochrane review established that compression garments worn during flight reduced oedema and the risk of symptomless DVT.3 Our findings show that low-ankle-pressure GCTs are effective at reducing flight-induced ankle oedema.

Our trial showed that even small quantitative increases in actual ankle circumference are associated with perceptions of leg swelling and associated pain and discomfort. This is consistent with the literature assessing compression stockings in healthy volunteers.14-16

Crew, and some passengers, actively work during flights. The impact from sleep disturbance (circadian rhythm disruption) and a reduced arterial partial pressure of oxygen (Pao2) have been implicated in reduced cognitive function in pilots17 and cabin crew.18 We explored self-assessed ratings of alertness, ability to concentrate and general energy levels in passengers. When wearing GCTs, participants had increased perceptions of alertness, ability to concentrate and higher energy levels compared with the flight where they did not wear GCTs. There are scarce data on passenger cognitive performance and recognition by research groups19 and other bodies of the need to conduct further studies.20

Visual analogue scales have been used to assess leg discomfort and swelling in flight attendants;2 however, only the pain intensity NRS adopted in this study has published reliability and validity in adults.21 While we made no objective tests of cognitive function, and unvalidated NRSs were used, our findings support improved cognitive function during flights when GCTs are worn, and further investigation is warranted.

A final consideration is the length of the garment which, as a full lower-body garment, applies pressure to about 45% of the body. Classic graduated-compression stockings are generally below-knee and apply pressure to about 18% of the body. A study comparing below-knee graduated-compression stockings with full lower-body GCTs would test the hypothesis that greater protection from depressurisation offered by these GCTs might lead to improvement in the quantitative and qualitative measures we assessed in this study. Further research on the comparative effects of total body GCTs is planned.

1 Recruitment and analysis for the study

GCTs = graduated-compression tights.

* 25 participants were randomly allocated to each group, but one participant allocated to Group 2 mistakenly followed the protocol for Group 1.

2 Baseline characteristics of the 47 study participants

Physical characteristics	Mean (95% CI)

Age	43 years (40–46 years)
Weight	81 kg (76–87 kg)
Height	173 cm (168–179 cm)


	Response
Leg symptoms and activity	Never	Rarely	Occasionally		Often	Every day

Leg pain during day	23.4%	51.1%	23.4%		2.1%	0
Leg pain during night	19.1%	57.4%	19.1%		4.3%	0
Ankle swelling	37.0%	37.0%	23.9%		2.2%	0
Play sport	19.1%	12.8%	34.0%		29.8%	4.3%
Exercise	0	4.3%	31.9%		53.2%	10.6%


	Proportion of time
Time at work	0	25%		50%	75%	100%

Spent sitting	0	8.5%		19.1%	57.4%	14.9%
Spent standing	25.5%	46.8%		17.0%	8.5%	0

3 Differences (means and 95% CIs) in selected parameters after flying with and without graduated-compression tights (GCTs)

Parameter	GCTs	No GCTs	P

Difference in ankle circumference (cm)	0.23 (0.13–0.32)	0.42 (0.32–0.52)	0.012
No. of alcoholic drinks — passengers	2.0 (1.1–2.8)	2.0 (1.2–2.8)	0.405
No. of non-alcoholic drinks — crew	7.4 (5.6–9.2)	8.7 (6.9–10.5)	0.082
No. of non-alcoholic drinks — passengers	4.0 (3.2–5.0)	4.6 (3.4–5.7)	0.405
Rating* for:
Leg pain	0.6 (0.4–0.9)	1.5 (1.0–2.0)	< 0.001
Leg discomfort	1.1 (0.8–1.7)	2.2 (1.6–2.8)	0.001
Perceived leg swelling	1.2 (0.7–1.6)	2.2 (1.6–2.9)	0.006
Energy levels	5.3 (4.7–5.9)	4.5 (4.0–5.0)	0.016
Alertness	5.3 (4.7–5.9)	4.7 (4.2–5.1)	0.031
Ability to concentrate	5.7 (5.1–6.3)	5.1 (4.6–5.7)	0.023
Flight duration (hours)	9.6 (8.4–10.8)	9.7 (8.4–11.0)	0.160

* Rated on a unidimensional, 11-point numerical rating scale.

Competing interests

Funding for this study was provided by Skins Compression Garments of Sydney, NSW. Melissa Hagan was contracted to conduct the study independently, and received no other funding from the company other than to conduct this research. Stephen Lambert is under contract as a scientific consultant for Skins Compression Garments. The study was initially designed by Stephen Lambert. Melissa Hagan independently collected, analysed and interpreted the data, and wrote the article. The agreement to publish the results was made prior to data collection with the Bellberry Human Research Ethics Committee, which approved this study. Skins Compression Garments had no influence over the decision to publish, and Melissa Hagan had final approval over the article’s content. The trial was registered with the Australian Clinical Trials Registry (trial no. 12606000150549) and was initiated on 19 April 2006.

Author detailsMelissa J Hagan, BSc, MEdSt, Researcher1Stephen M Lambert, RN, MAppSc, Exercise Physiologist2

1 MPro, Brisbane, QLD.

2 The University Clinic, Westmead Hospital, Sydney, NSW.

Correspondence: melissahaganATbigpond.com

References

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Clarke M, Hopewell S, Juszczak E, et al. Compression stockings for preventing deep vein thrombosis in airline passengers. Cochrane Database Syst Rev 2006; (2): CD004002.
Belcaro G, Cesarone MR, Shah SS, et al. Prevention of edema, flight microangiopathy and venous thrombosis in long flights with elastic stockings. A randomized trial: the LONFLIT 4 Concorde Edema–SSL Study. Angiology 2002; 53: 635-645. <PubMed>
Byrne B. Deep vein thrombosis prophylaxis: the effectiveness and implications of using below-knee or thigh-length graduated compression stockings. Heart Lung 2001; 30: 277-284. <PubMed>
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(Received 16 May 2007, accepted 11 Sep 2007)

Your Health Inflight

At Qantas we care about your comfort and safety. We have included the following information about your health inflight that we hope you will find helpful and useful.

When you are flying you can be seated and inactive for long periods of time. The environment can be low in humidity and pressurised up to an altitude of 2440 metres above sea level. Unlike other forms of transportation, air travel allows for rapid movement across many time zones, causing a disruption to the body's 'biological clock'.

Although these factors do not pose a health or safety threat to most customers, there are guidelines you can follow that will aid comfort during and after a flight.

Cabin Humidity and Dehydration

Humidity levels of less than 25 percent are common in the cabin. This is due to the extremely low humidity levels of the outside air supplied to the cabin. The low humidity can cause drying of the nose, throat and eyes and it can irritate wearers of contact lens.

We recommend that you:

Drink water and juices frequently during your flight.
Drink coffee, tea and alcohol in moderation. These drinks act as diuretics, increasing the body's dehydration.
Remove contact lenses and wear glasses if your eyes are irritated.
Use a skin moisturiser to refresh the skin.

Eating and Drinking

Proper eating and drinking will enhance your comfort both during and after your flight.

We recommend that you:

Avoid overeating just before and during the flight. It is difficult to digest too much food when the body is inactive.
Drink coffee, tea and alcohol in moderation. These drinks act as diuretics, increasing the body's dehydration.

Blood Circulation and Muscle Relaxation

When you're sitting upright and inactive for a long period of time, several things can happen:

The central blood vessels in your legs can be compressed, making it harder for the blood to get back to your heart.
Muscles can become tense, resulting in backaches and a feeling of excessive fatigue during, and even after your flight.
The normal body mechanism for returning fluid to the heart, can be inhibited and gravity can cause the fluid to collect in your feet, resulting in swollen feet after a long flight.
Some studies have concluded that prolonged immobility may be a risk factor in the formation of blood clots in the legs, deep vein thrombosis (DVT). Particular medications and medical conditions may increase the risk of formation of blood clots if associated with prolonged immobility.

Medical research indicates that factors that may give you an increased risk of blood clots in the legs include:

Personal or family history of DVT.
Recent surgery or injury, especially to lower limbs or abdomen.
Blood disorders leading to increased clotting tendency.
Immobilisation for a day or more.
If you are aged above 40 years.
Oestrogen hormone therapy, including oral contraceptives.
Pregnancy.
Tobacco smoking.
Former or current malignant disease.
Obesity.
Dehydration.
Heart failure.
Varicose veins.

Recommendations:

If any of these categories apply to you or you have any concerns about your health and flying, we recommend you seek medical advice before travelling.
Compression stockings can assist in preventing swelling of the ankles and feet and they may improve the blood return to the body from the lower legs. You may like to talk to your doctor about this. The stockings may be purchased from medical and surgical supply companies and will need to be individually fitted to your leg measurements.
While inflight, move your legs and feet for three to four minutes per hour while seated and move about the cabin occasionally.
Do the light exercises recommended below in the Inflight Workout section.

Inflight Workout

These exercises are designed to provide a safe way to stretch and enjoy movement in certain muscle groups that can become stiff as a result of long periods of sitting. They may be effective at increasing the body's blood circulation and massaging the muscles.

We recommend that you do these exercises for around three or four minutes every hour and occasionally get out of your seat and walk down the aisles.

Each exercise should be done with minimal disturbance to other passengers. None of the following exercises should be performed if they cause pain or cannot be done with ease.

Ankle circles

1. Ankle Circles

Lift feet off the floor. Draw a circle with the toes, simultaneously moving one foot clockwise and the other foot counterclockwise. Reverse circles. Rotate in each direction for 15 seconds. Repeat if desired.

2. Foot Pumps

Foot motion is in three stages.
1. Start with both heels on the floor and point feet upward as high as you can.
2. Put both feet flat on the floor.
3. Lift heels high, keeping balls of feet on the floor.
Repeat these three stages in a continuous motion and in 30-second intervals.

3. Knee Lifts

Lift leg with knee bent while contracting your thigh muscle. Alternate legs. Repeat 20 to 30 times for each leg.

4. Neck Roll

With shoulders relaxed, drop ear to shoulder and gently roll neck forward and back, holding each position about five seconds. Repeat five times.

5. Knee to Chest

Bend forward slightly. Clasp hands around the left knee and hug it to your chest. Hold stretch for 15 seconds. Keeping hands around the knee, slowly let it down. Alternate legs. Repeat 10 times.

6. Forward Flex

With both feet on the floor and stomach held in, slowly bend forward and walk your hands down the front of your legs toward your ankles. Hold stretch for 15 seconds and slowly sit back up.

7. Shoulder Roll

Hunch shoulders forward, then upward, then backward, and downward, using a gentle circular motion.

Cabin Pressurisation

It is necessary to pressurise the outside air drawn into the cabin to a sufficient density for your comfort and health. Cabins are pressurised to a maximum cabin altitude of 2440 metres.

The cabin pressure and normal rates of change in cabin pressure during climb and descent do not pose a problem for most customers. However, if you suffer from upper respiratory or sinus infections, obstructive pulmonary diseases, anaemias or certain cardiovascular conditions, you could experience discomfort.

Children and infants might experience some discomfort because of pressure changes during climb and descent.

If you are suffering from nasal congestion or allergies, use nasal sprays, decongestants and antihistamines 30 minutes prior to descent to help open up your ear and sinus passages.

If you have a cold, flu or hay fever, your sinuses could be impaired. Swollen membranes in your nose could block your Eustachian tubes - the tiny channels between your nasal passages and your middle ear chamber. This can cause discomfort during changes in cabin pressure, particularly during descent.

Recommendations:

If you have a pre-existing medical condition that warrants supplemental oxygen, you can order it from us. Please give at least seven days' notice before travelling.
To 'clear' your ears, try swallowing or yawning. These actions help open your Eustachian tubes, equalising pressure between your middle ear chamber and your throat.
When flying with an infant, feed or give your baby a dummy during descent. Sucking and swallowing will help infants equalise the pressure in their ears.

Jet Lag

The main cause of jet lag is travelling to a different time zone without giving the body a chance to adjust to new night and day cycles. In general, the more time zones you cross during your flight, the more your biological clock is disturbed. The common symptoms are sleeplessness, tiredness, loss of appetite or appetite at odd hours.

To try to minimise the effects of jet lag, we recommend that you:

Get a good night's rest before your flight.
If possible, give yourself a day or two to adjust to the new time zone after arrival.
Fly direct to minimise flight time, if you can. This allows you to relax more upon arrival.
Try some light exercise, go for a brisk walk, or do some reading, if you can't sleep after arrival at your destination. It generally takes the body's biological clock approximately one day to adjust per time zone crossed.

Motion Sickness

This ailment is caused by a conflict between the body's sense of vision and its sense of equilibrium. Air turbulence increases its likelihood because it can cause movement of the fluid in the vestibular apparatus of the inner ear. If you have good visual cues (keeping your eyes fixed on a non-moving object), motion sickness is less likely to occur.

Recommendations:

When the weather is clear and you can see the ground, sea or horizon, you are less susceptible to motion sickness.
You can buy over the counter medications but we recommend that you consult your doctor about the appropriate medications.

Cosmic Radiation

Cosmic radiation is the collective term for the radiation that comes from the sun and from the galaxies of the universe.

The earth's atmosphere substantially shields the earth from cosmic radiation. However the dose of cosmic radiation increases with:

increasing altitude,
length of the flight, and
increasing latitude (getting closer to the north or south pole).

Like radiation from other sources, cosmic radiation is measured in sieverts (Sv). Annual doses are measured in millisieverts (mSv) which are thousandths of a sievert. Measurements on Qantas aircraft on individual sectors are measured in microsieverts (uSv) which are millionths of a sievert.

All humans are exposed to background radiation at sea-level. This comes from sources such as the local environment, food and drink, medical exposure and building materials. In high doses, radiation can be harmful. However, the doses received at flight altitudes are considered very low. The world average background radiation level is 2.4 mSv per year and the average Australian dose is approximately 2 mSv each year.

Recommended limits

The Australian Radiation Protection and Nuclear Safety Agency (ARPANSA) recommends the following limits for flying:

For occupational exposure on commercial air flights (for example, pilots and flight attendands) is 20 mSv per year.
For the general public on commercial air flights is 1 mSv. This includes flying when pregnant.

Most public travellers in Australia would not be exposed to more than 1 mSv per year. A regular business traveller is likely to be exposed to more than 1 mSv per year, but assuming that they are undertaking the majority of their travel for business, they will come within the occupational exposure limits. Pregnant women should not be exposed to more than 1mSv per year.

Qantas pilots and flight attendants who operate international flights are exposed to approximately 3-4 mSv per year (that is 20% of the ARPANSA exposure limit). Qantas domestic pilots and flight attendants are exposed to approximately 2 mSv per year. This is low when compared to Computerised Tomography (CT) scans of the chest (8 mSv) or abdomen (5-30 mSv).

You can find out more about cosmic radiation on The Australian Radiation Protection and Nuclear Safety Agency website.