Guidelines on Jet-Lag Posted on Tuesday, September 09, 2003 - 00:00 Introduction Every human being has a built-in clock that regulates most physiological functions. This is called the circadian rhythm and it regulates sleep, wakefulness, hunger, digestion, concentration, body temperature, and other functions such the secretion of enzymes and hormones in the body. For example these circadian rhythms determine that a person will feel most sleepy between 2 and 4 am and thus other sense are dulled at this time. Another example is where people feel hungry at a specific time because of digestion patterns and the secretion of enzyme is related to this circadian rhythm. Thus when one crosses multiple time zones a new set of times is imposed on the body. This new time will determine sleeping times, eating times and training times. This will obviously conflict with the in-built circadian rhythm and will cause symptoms of Jet Lag (see table 1 which illustrates this). New local time Requirement Body time Desire 08.00 Waking 23.00 Sleep 16.00 Peak activity 07.00 Begin to awake 24.00 Retiring to sleep 15.00 Peak activity These symptoms occur whether the travel is from east to west or vice versa, but is more significant when traveling west to east. The symptoms experienced as a result of jet lag are very different to the tiredness and general discomfort that one feels after a long journey, whether by road or by air. This tiredness is due to the stress of preparing for the journey as well as the actual journey, the dehydrating effects of the plane environment (dry air on board), acclimatising to the new environment and the anxiety of the competition. This effect is not related to traveling across time zones. The symptoms of jet-lag and travel fatigue occur simultaneously. Travel fatigue, however, generally resolves within 24 to 48 hours. Jet lag is also transient and periodic and with appropriate interventions should not be a major issue for traveling teams, which arrive at a destination in good time to allow for adjustment of the body clock before the first competition. With the management strategies recommended in this document, the symptoms of jet-lag should not persist beyond a few days. Symptoms of jet-lag § Fatigue during the “new” daytime § Inability to sleep at night § Difficulty concentrating on tasks § Irritability § Disorientation and mental confusion § Headaches § Loss of vigour § A loss of appetite coupled with indigestion and even nausea § Change in normal bowel activity most frequently constipation Performance effects § Decreased mental performance, particularly if vigilance is required; § Decreased physical performance, particularly with regard to events that require stamina or precise movement; § Impairment of muscle function § Decreased reaction time § Increased “rate of perceived exertion” for the same tasks Determinants of severity Jet lag symptoms and effects tend to be more severe when traveling from west to east than from east to west because the human body reacts better to a lengthening, rather than shortening, of the day. South African teams when playing in Australia and New Zealand are therefore at a greater disadvantage than the Oceanic teams (Australia, New Zealand and Fiji) who travel from east to west for away games. There is some evidence that trained sportspersons tend to cope better with jet lag than untrained persons. Thus administrators and coaches would be more affected than athletes. Jet-lag seems to affect older individuals more severely. The effects of jet lag are more pronounced at certain times of the day. This would obviously depend on the normal circadian rhythm and the adjustment needed in a foreign environment. Restoration of biological rhythm The rule of thumb is that it takes one day, on average, for acclimatization to occur, per time zones crossed, after an eastward flight and about half the number after a westward flight. Thus it would theoretically take South Africans who are traveling to Oceanic countries between 9 and 11 days to recover from jetlag. It needs to be remembered however that some athletes may take longer to adjust. Strategies to reduce jet-lag symptoms There are three broad categories of interventions that would reduce the effects of jet lag. These are: Behavioural interventions: what you do before and after the trip. This would include sleep patterns, exposure to natural light, exercise, etc. A positive attitude and mental toughness are important in coping with this inconvenience. Drug interventions: the use of certain drugs, for example hypnotics and stimulants, to aid adjustment. The other drug used specifically to readjust the body clock is melatonin. Dietary interventions: certain dietary practices and use of food groups would also assist adjustment. The timing of the meal seems to be more important than the specific type of food consumed. The adaptation from jet-lag is a complex phenomenon, which integrates internal body responses, behavioural responses and environmental conditions. In relation to the latter, natural sunlight plays and important role in determining the circadian rhythm. Thus behavioural changes must be instituted in concert with the proper environmental cues for maximum effect. i) Before the Flight. - If possible, schedule flights so that players arrive well in advance of competition. As a general rule one day for each time zone crossed must be allowed. In the event of Oceanic traveling it is therefore advised to arrive at least 7 days prior to the commencement of competition. - In the week before departure, work towards adopting destination times for training, meals and sleep (i.e. time of rising and going to bed). A change of more than 2 hours is unlikely to be productive since this would interfere with the normal activities and time cues from the environment. - Eat a high protein breakfast with caffeinated beverages and switch to caffeine-free, carbohydrate-rich foods/drinks (these have sedative properties) in the afternoon and evening meals and snacks may help this adjustment. - Have a nap before leaving home. - Pre-arrange all meals and snacks taken in transit. - Pack some portable carbohydrate-rich snacks (higher fibre options like breakfast and dried fruit bars, fresh and dried fruit, whole-wheat crackers), sports bars, liquid meal/snack replacements, and sports drinks into carry-on baggage. - Plan flight activities in advance e.g. sleep times, meal times and how to deal with meals if missed, taking into account transit times and possible delays. ii) During the Flight. - Once on board the plane, set watches to coincide with local time of the next point of landing. This will allow you to mentally frame yourself into the new environment. Your eating, drinking and sleeping times should be in accordance with the new time. - Ensure that you perform periodic gentle exercises on the plane in order to keep your blood from circulating and to prevent conditions such as deep-vein thrombosis. - If arrival at the final destination is during daytime make every attempt to sleep on the plane. Some short-acting benzodiazipines (sleeping tablets) have proven to be effective in inducing and maintaining sleep for 4-6 hours while allowing players to wake up alert and without adverse effects (see below). Ensure that you sleep is in accordance with the host country times. - Alcohol, tea and coffee should be avoided and plenty fruit juices (e.g. tomato juice), water, non-fizzy cordials and sports drinks should be consumed. - The last meal prior to the time allotted for sleep should be high in carbohydrate and low in protein. This will induce sleep. - On waking, to help raise the level of arousal and prevent a relapse into sleep, a high protein breakfast with coffee/tea can be consumed. - Should the time of arrival at the destination be at night, players should refrain from sleeping in the plane. Instead they should do static exercises in their seats or walk inside the plane as much as they can. iii) Upon Arrival - Adjust to the destination’s time as soon as possible. - Avoid sleeping during the daytime. Ensure that you get adequate sleep at night as this will accelerate adjustment to the new time. - Bright light can “advance” the body clock so exposure to sunlight (outdoors) instead of getting into bed upon arrival is advised. The best time to go out in the sunlight at the destination point, when travelling east, would be between 11h00 and 17h00. - Increase total fluid intake and time the intake of caffeinated beverages (e.g. coffee/tea/colas) to coincide with periods of high arousal. - Evening meals and snacks should be high in carbohydrate (eg. pasta, potatoes, rice, breads, vegetables, fruit, low fat dairy drinks/desserts) - Some athletes find Melatonin supplementation helpful whilst others may find it detrimental. It needs to be borne in mind that melatonin supplementation taken inappropriately may be more detrimental than beneficial. If you prefer taking it then ensure proper usage (see below). - Arrange training sessions in late afternoon and try to keep them to the bare-minimum in the first couple of days. In the first few days they should be kept at low intensity and lasting not more than an hour. - If your stay in the host country is less than 3 days, then feel free to sleep when you feel tired, ensuring that in addition you get good nights sleep. Pharmacological interventions All the drugs and substances mentioned below are not banned in sport. Sleeping tablets: Some sleeping tablets have proven to be useful in inducing sleep. However, these tablets should only be used if jet-lag symptoms still remain pronounced after adopting the strategies described above. These drugs should not be taken for more than 3-5 days. The recommended drugs and dosages are given below (trade names): - Imovane 7.5 mg before retiring - Dormicum 7.5 to15mg - Dormonoct 2mg - Stilnox 10mg - Zopimide 15mg - Lendormin 0.25 mg Please remember that these drugs may cause drowsiness and should not be taken with alcohol. Melatonin Melatonin is a neurotransmitter/neurohormone, which occurs naturally in the body. It is produced by the pineal gland in the brain and plays an important role in maintaining the circadian rhythm. Melatonin must be taken according to the directions given otherwise it can have detrimental effects. Sunlight inhibits natural melatonin secretion and works antagonistically, thus natural melatonin secretion peaks at night. Thus melatonin ingestion must be accompanied by appropriate environmental cues – avoid bright lights and after taking melatonin retire to a darkened room. When travelling eastward the recommendation is to take 5 mg melatonin an hour before going to sleep in the country of destination. Do not take melatonin for more than five days. Precaution: those with epilepsy or those taking warfarin must not take melatonin. Caffeine Caffeine is a stimulant and can be used to counter the effects of jet lag induced fatigue and sleepiness. Caffeine is best taken in its ‘natural’ form – such as in tea and coffee. It must be remembered that caffeine is a banned substance in terms of the IOC anti-doping code. An excess of caffeine can result in a doping offence. However one or two cups of tea or coffee are unlikely to increase the levels of caffeine beyond the permitted levels. References Herxheimer A, Petrie KJ. Melatonin for the prevention and treatment of jet lag (Cochrane Review). In: The Cochrane Library, Issue 3 2002. Oxford: Update Software. Waterhouse J, Reilly T and Atkinson G. Travel and body clock disturbances. SA J of Sports Med 1997 ; 4(3): 4-9. Waterhouse J, Edwards B, Neville A, et al. Identifying some determinants of “jet lag” and its symptoms: a study of athletes and other travelers. Br J Sports Med 2002; 36 (1):54-60. Reilly T. Travel-Chronobiology. In Proceedings of the FIFA Conference on Science and Football, Los Angeles, California, March 2002. Petrie K, Dawson AG, Thomson L, Brook R. A double-blind trial of melatonin as a treatment in international cabin crew. Biological Psychiatry 1993; 33(7): 526-530. Produced by SA Rugby Scientific and Research Committee