Westward Flight Research Articles

The effect of westward travel across five time zones on sleep and subjective jet-lag ratings in athletes before and during the 2015’s World Rowing Junior Championships

ABSTRACTThis study examined sleep-wake habits and subjective jet-lag ratings of 55 German junior rowers (n = 30 male, 17.8 ± 0.5 years) before and during the World Rowing Junior Championships 2015 in Rio de Janeiro, Brazil. Athletes answered sleep logs every morning, and Liverpool John Moore’s University Jet-Lag Questionnaires each evening and morning. Following an 11-h westward flight with 5-h time shift, advanced bedtimes (−1 h, P < .001, ηp2 = 0.68), reduced sleep onset latency (P = .002, ηp2 = 0.53) and increased sleep duration (P < .001, ηp2 = 0.60) were reported for the first two nights. Jet-lag symptoms peaked upon arrival but were still present after 6 days. Sleep quality improved (P < .001, ηp2 = 0.31) as well as some scales of the Recovery-Stress Questionnaire for Athletes. Participation was successful as indicated by 11 of 13 top 3 placings. Overall, the initial desynchronisation did not indicate negative impacts on competition performance. As travel fatigue probably had a major effect on perceptual decrements, sleep during travel and time to recover upon arrival should be emphasised. Coaches and practitioners should consider higher sleep propensity in the early evening by scheduling training sessions and meetings until the late afternoon.

From Twelve Circles

In this excerpt from the novel Twelve Circles, photographer Karl-Joseph Zumbrunnen takes leave of his earthly body and experiences an unexpected lightness of being. It is just before dawn on Easter Sunday, but he does not turn toward the resurrection of the rising sun; he sets instead on a westward flight, away from the Ukrainian town where he was killed, toward Vienna. His journey will follow the contour of the oval formed by the Carpathian Mountains, the center of Europe, according to the text, and take him from Transylvania, along the Danube, to a light-filled crowded stadium to which he is admitted after having answered a ritual question. The topography of his itinerary is matched by the topology of his memory, as he sees a forlorn lover working on the 112th page of a draft letter, various lovers sleeping in each other’s arms, and the train stations that were to be the subject of his next project. When his astral body is absorbed by the light of the stadium, the author takes leave of his readers, but not before knocking on wood.

Impact of Layover Length on Sleep, Subjective Fatigue Levels, and Sustained Attention of Long-Haul Airline Pilots

Long-haul airline pilots often experience elevated levels of fatigue due to extended work hours and circadian misalignment of sleep and wake periods. During long-haul trips, pilots are typically given 1–3 d off between flights (i.e., layover) to recover from, and prepare for, duty. Anecdotally, some pilots prefer long layovers because it maximizes the time available for recovery and preparation, but others prefer short layovers because it minimizes both the length of the trip, and the degree to which the body clock changes from “home time” to the layover time zone. The aim of this study was to examine the impact of layover length on the sleep, subjective fatigue levels, and capacity to sustain attention of long-haul pilots. Participants were 19 male pilots (10 Captains, 9 First Officers) working for an international airline. Data were collected during an 11- or 12-d international trip. The trips involved (i) 4 d at home prior to the trip; (ii) an eastward flight of 13.5 h across seven time zones; (iii) a layover of either 39 h (i.e., short, n = 9) or 62 h (i.e., long, n = 10); (iv) a return westward flight of 14.3 h across seven time zones; and (v) 4 d off at home after the trip. Sleep was recorded using a self-report sleep diary and wrist activity monitor; subjective fatigue level was measured using the Samn-Perelli Fatigue Checklist; and sustained attention was assessed using the psychomotor vigilance task for a personal digital assistant (PalmPVT). Mixed-model regression analyses were used to determine the effects of layover length (short, long) on the amount of sleep that pilots obtained during the trip, and on the pilots' subjective fatigue levels and capacity to sustain attention. There was no main effect of layover length on ground-based sleep or in-flight sleep, but pilots who had a short layover at the midpoint of their trip had higher subjective fatigue levels and poorer sustained attention than pilots who had a long layover. The results of this study indicate that a short layover during a long-haul trip does not substantially disrupt pilots' sleep, but it may result in elevated levels of fatigue during and after the trip. If short layovers are used, pilots should have a minimum of 4 d off to recover prior to their next long-haul trip. (Author correspondence: greg.roach@cqu.edu.au)

Temporal Variations of Coagulation Factor VII Activity in Mice Are Influenced by Lighting Regime

It was recently reported that the circadian clock machinery controls plasma levels of factor (F) VII, the serine protease triggering blood coagulation. Here, by exploiting the mouse model, this study showed that variations of photoperiod (i.e., winter or summer conditions or simulated chronic jetlag conditions) have a strong impact on plasma FVII activity levels. Under conditions mimicking summer or winter photoperiods, FVII activity showed a clear 24 h rhythmicity. Interestingly, mean daily FVII activity levels were significantly reduced in mice exposed to summer photoperiods. Behavioral activity rhythms under both photoperiods were synchronized to LD cycles, and the amount of activity per 24 h was comparable. The authors also investigated the influence of chronic jetlag (CJL) on the FVII activity rhythms, which can be easily mimicked in mice through continuous abrupt shifts in the lighting schedule. The exposure of mice to simulated CJL of either consecutive westward or consecutive westward and eastward flights for 15 days did not abolish the behavioral activity rhythms but was associated with a period significantly different from 24 h. Intriguingly, both types of CJL exerted a strong influence on FVII activity rhythms, which were virtually suppressed. Moreover, the mean daily FVII activity was significantly lower in the CJL than in the winter photoperiod condition. Taken together, these findings in mice provide novel insights into the modulation of FVII activity levels, which might have implications for human pathophysiology.

Sleep and intercontinental flights

At present there are no 'high-tech' solutions to the problems that may beset intercontinental travellers. Indications for the use of drugs are limited, and their use must accord with Good Clinical Practice. Essentially, travellers must look after their sleep, as far as possible, during and after the flight. The most useful time for sleep during the flight must be anticipated, caution exercised in the use of hypnotics in-flight as reduced mobility is a potential risk factor for venous thrombosis, and a strategy adopted, whether flying east or west, to adapt as quickly as possible to the working hours of the new locality. After an eastward flight a hypnotic may be useful, but this strategy is seldom necessary after a westward flight unless the journey has involved crossing more than 5 or 6 time zones. The claim that melatonin accelerates the shift of the sleep-wakefulness cycle to a new time zone is controversial, and its recommended use may prejudice alertness during working hours. Exposure to artificial light and avoidance of ambient light at certain times of the day could prove to be of help-possibly in conjunction with drugs. However, effective and practical alterations in the light environment must be devised before such strategies can be considered with confidence.

Modeling interactions between photic and nonphotic entrainment mechanisms in transmeridian flights.

In transmeridian flights, photic and nonphotic entrainment mechanisms are expected to interact dynamically in the human circadian system. In order to simulate the reentrainment process of the circadian rhythms, the photic entrainment mechanism was introduced to our previous model, which consisted of three coupled oscillators. Regardless of flight direction, a large time difference beyond 10 h tended to induce the antidromic reentrainment. The partition between the oscillators resulted for the eastward flight over a 10-h or longer time difference and the westward over 6 h or longer. The simulated reentrainment processes almost coincided with empirical knowledge. Simulated effects of physical exercise showed that some antidromic reentrainments were switched to the orthodromic ones for the eastward flight and most of the partitions between the oscillators were prevented in the westward flight. These results are due to an augmentation of the entrainment pressure of the rest-activity cycle on the oscillators. The mechanisms underlying these various reentrainment patterns were explained based on the photic response, the interactions between the oscillators, and their adaptive modification. The simulation results suggest that an appropriate selection of departure time and physical exercise could ease the jet lag caused by transmeridian flight.

Comparison of a westward flight and an eastward flight in the circadian rhythms of plasma melatonin

We estimated the re-entrainment of plasma melatonin rhythm after an eastward flight to New York in 2000 and after a westward flight to London in 2001. Blood samples were taken at 1.5 h intervals for 24-h from eight subjects once before the flight and twice after the flight. They were exposed to natural zeitgeber outdoors. The symptoms of six subjects were moderate in London. All subjects showed the orthodromic re-entrainment, and the phase shift was small (46.3 min/day) in the westward flight. It seemed that the direction of flight was as important for jet lag symptoms as was sunlight exposure.

The Use of Actimetry to Assess Changes to the Rest–Activity Cycle

The endogenous circadian oscillator (the body clock) is slow to adjust to altered rest–activity patterns. As a result, several negative consequences arise during night work and after time‐zone transitions. The process of adjustment can be assessed by measurements of the sleep electroencephalogram (EEG), core temperature or melatonin secretion, for example, but these techniques are very difficult to apply in field studies, and make very great demands upon both experimenters and subjects. We have sought to establish if the activity record, measured conveniently and unobtrusively by a monitor attached to the wrist, can be treated in ways that enable estimates to be made of the disruption caused by changes to the rest–activity cycle, and the process of adjustment to them. In Part A, we describe the calculation and assessment of a series of “activity indices” that measure the overall activity pattern, activity when out of bed or in bed, or the activity in the hours adjacent to going to bed or getting up. The value of the indices was assessed by measuring changes to them in subjects undergoing night work or undergoing time‐zone transitions. In both cases, there is a large body of literature describing the changes that would be expected. First, night workers (working 2 to 4 successive night shifts) were investigated during rest days and night shifts. The indices indicated that night work was associated with lower activity when the subjects were out of bed and higher activity when in bed. Some indices also measured when subjects took an afternoon nap before starting a series of night shifts and gave information about the process of adjustment to night work and recovery from it. Second, in studies from travelers crossing six or more time zones to the east or west, the indices indicated that there were changes to the rest–activity cycle immediately after the flights, both in its overall profile and when activity of the subjects in bed or out of bed was considered, and that adjustment took place on subsequent days. By focusing on those indices describing the activity records during the last hour in bed (LHIB) and the first hour out of bed (FHOB), some evidence was found for incomplete adjustment of the body clock, and for differences between westward and eastward flights. In Part B, the battery of indices are applied to the activity records of long‐haul pilots, whose activity patterns showed a mixture of effects due to night work and time‐zone transitions. Actimetry was performed during the flights themselves and during the layover days (which were either rest or work days). The indices indicated that all pilots had disrupted rest–activity cycles caused by night flights, and that there were added problems for those who had also undergone time‐zone transitions. Rest days were valuable for normalizing the activity profile. For those pilots who flew to the west, adjustment was by delay, though not all aspects of the rest–activity cycle adjusted immediately; for those who flew to the east, some attempted to advance their rest–activity cycle while others maintained home‐based activity profiles. The indices indicated that the activity profile was disrupted more in those pilots who attempted to advance their rest–activity cycle. We conclude that objective estimates of the disruption caused to the rest–activity cycle and the circadian system can be obtained by suitable analysis of the activity record.

Melatonin for the prevention and treatment of jet lag.

: Jet-lag commonly affects air travellers who cross several time zones. It results from the body's internal rhythms being out of step with the day-night cycle at the destination. Melatonin is a pineal hormone that plays a central part in regulating bodily rhythms and has been used as a drug to re-align them with the outside world. : To assess the effectiveness of oral melatonin taken in different dosage regimens for alleviating jet-lag after air travel across several time zones. : We searched the Cochrane Controlled Trials Register, MEDLINE, EMBASE, PsychLit and Science Citation Index electronically, and the journals 'Aviation, Space and Environmental Medicine' and 'Sleep' by hand. We searched citation lists of relevant studies for other relevant trials. We asked principal authors of relevant studies to tell us about unpublished trials. Reports of adverse events linked to melatonin use outside randomised trials were searched for systematically in 'Side Effects of Drugs' (SED) and SED Annuals, 'Reactions Weekly', MEDLINE, and the adverse drug reactions databases of the WHO Uppsala Monitoring Centre (UMC) and the US Food & Drug Administration. : Randomised trials in airline passengers, airline staff or military personnel given oral melatonin, compared with placebo or other medication. Outcome measures should consist of subjective rating of jet-lag or related components, such as subjective wellbeing, daytime tiredness, onset and quality of sleep, psychological functioning, duration of return to normal, or indicators of circadian rhythms. : Ten trials met the inclusion criteria. All compared melatonin with placebo; one in addition compared it with a hypnotic, zolpidem. Nine of the trials were of adequate quality to contribute to the assessment, one had a design fault and could not be used in the assessment. Reports of adverse events outside trials were found through MEDLINE, 'Reactions Weekly', and in the WHO UMC database. : Nine of the ten trials found that melatonin, taken close to the target bedtime at the destination (10pm to midnight), decreased jet-lag from flights crossing five or more time zones. Daily doses of melatonin between 0.5 and 5mg are similarly effective, except that people fall asleep faster and sleep better after 5mg than 0.5mg. Doses above 5mg appear to be no more effective. The relative ineffectiveness of 2mg slow-release melatonin suggests that a short-lived higher peak concentration of melatonin works better. Based on the review, the number needed to treat (NNT) is 2. The benefit is likely to be greater the more time zones are crossed, and less for westward flights. The timing of the melatonin dose is important: if it is taken at the wrong time, early in the day, it is liable to cause sleepiness and delay adaptation to local time. The incidence of other side effects is low. Case reports suggest that people with epilepsy, and patients taking warfarin may come to harm from melatonin. : Melatonin is remarkably effective in preventing or reducing jet-lag, and occasional short-term use appears to be safe. It should be recommended to adult travellers flying across five or more time zones, particularly in an easterly direction, and especially if they have experienced jet-lag on previous journeys. Travellers crossing 2-4 time zones can also use it if need be. The pharmacology and toxicology of melatonin needs systematic study, and routine pharmaceutical quality control of melatonin products must be established. The effects of melatonin in people with epilepsy, and a possible interaction with warfarin, need investigation.

Reataining Home-Base Sleep Hours to Prevent Jet Lag in Connection with a Westward Flight Across Nine Time Zones

The aim of this study was to test a possible countermeasure to jet lag: letting air crew retain their home-base sleep/wake pattern during layover. Instead of their usual adoption of local sleep hours, 19 flight attendants were scheduled to a westward layover (50h) flight (Copenhagen-Los Angeles, -9h) on two occasions. On one trip, crews adopted the local sleep pattern, and on the other trip, the crew retained home-base sleep hours. Subjects were monitored for 10 days before, during, and after the flight; they wore activity loggers and gave ratings through sleep/wake diaries and a questionnaire. Ratings of jet lag symptoms and sleepiness were greatly reduced during layover, but not at home, for the home-base condition. It was also found that jet lag feelings seemed to be related mainly to mean sleepiness ratings (multiple regression; 16%, beta = 0.46) and to the number of awakenings (6%, beta = 0.29) during sleep. It is concluded that retaining the home-base sleep pattern may reduce jet lag during layover.

Chronobiotic effect of melatonin following phase shift of light/dark cycles in the field mouseMus booduga

The objective of this study was to assess whether melatonin accelerates the re- entrainment of locomotor activity after 6 h of advance and delay phase shifts following exposure to LD 12:12 cycle (simulating jet-lag/shift work). An experimental group of adult male field mice Mus booduga were subjected to melatonin (1 mg/kg) through i.p. and the control group were treated with 50 % DMSO. The injections were administered on three consecutive days following 6h of phase advance and delay, at the expected time of "lights off'. The results show that melatonin accelerates the re-entrainment after phase advance (29%) when compared with control mice. In the 6 h phase delay study, the experimental mice (melatonin administered) take more cycles for re-entrainment (51%) than the control. Further, the results suggest that though melatonin may be useful for the treatment of jet-lag caused by eastward flight (phase advance) it may not be useful for westward flight (phase delay) jet-lag.

The effect of four-day round trip flights over 10 time zones on the sleep-wakefulness patterns of airline flight attendants

To study the effect of a four-day-round trip flight on the sleep-wakefulness of airline flight attendants, subjective sleep-wakefulness and autonomic sleep phases were measured. Forty flight attendants (mean age 33 years, range 21-50) kept daily logs on sleepiness, the time when going to bed, and sleep quality. In addition, the autonomic sleep phases of 21 subjects were studied by the static charge sensitive bed (SCSB) method. After the westward flight, the subjects went to bed approximately 1-3 h local time earlier during the first few days and were very sleepy compared to the week before the flight. There was a significant increase in the number of awakenings and in the feeling of 'not being at all rested' in the mornings. After the return flight eastwards, the subjects were very sleepy on the first evening but slept rather well for about 11 h. During the three following days, sleep restlessness, difficulties in falling asleep, and the feelings of sleepiness in the mornings increased compared to the week before the flights. Four days after the return flight, sleep length and the quality of sleep were, on average, the same as before the flights. According to the SCSB method, there were only small changes in the autonomic sleep phases due to the flights. After the westward flight, quiet sleep increased and intermediate sleep decreased compared to the sleep before the flight. The results indicate that most flight attendants have significant disturbances in sleep quality after transmedian flights. Sleep disturbances increase after both westward and eastward transmedian flights, but differ from each other in specific features.

The effect of four-day round trip flights over 10 time zones on the circadian variation of salivary melatonin and Cortisol in airline flight attendants

The effects of four-day round flights (Helsinki-Los Angeles-Seattle-Helsinki) were studied on the circadian rhythms of salivary melatonin (MT) and cortisol (COR) in 35 flight attendants. The mean age of the subjects was 33 +/- 7 years (median 34, range 21-50). Five 24 h profiles of unstimulated saliva were collected at 2 h intervals (except at 04:00) before, during, and after the four day flight. Salivary MT and COR were determined by radioimmunoassay. Both MT and COR exhibited a clear circadian rhythm with acrophases before the flight at 03:03 (MT) and 09:08 (COR). Two days after the westward flight from Helsinki to Los Angeles, the MT rhythm (circadian acrophase) had delayed 4 h 51 min and the COR rhythm 3 h 55 min compared to the control day before the flight. Two days later, during the last day in the USA, the MT rhythm had delayed 5 h 59 min and the COR rhythm 5 h 29 min as compared to the situation before the flight. After four days of the eastward flight from Seattle to Helsinki, the circadian acrophase of MT was still 1 h 35 min delayed compared to the control day before the westward flight. The results indicate that the restitution time of five days at the home base is on the average proper for recovery, if a four day round flight over 10 time zones takes four days or less. The resynchronization rate of salivary hormones after westward, outgoing flights is faster than the resynchronization rate after the eastward return flights.

Insulin treatment, time-zones and air travel: a survey of current advice from British diabetic clinics.

To investigate current advice given to insulin-treated diabetic patients undertaking international flights crossing time-zones, we have conducted a survey of UK physicians running diabetic clinics. Consultants were asked to give the general advice they would give to travellers on twice-daily short- and intermediate-acting insulins in four different flight situations: westward London to New York (morning and evening departures) and eastward Manchester to Singapore (morning and evening departures). Response rate was poor (37%). Six percent of replies were unhelpful (e.g. 'ring the BDA', 'carry on as usual'), and 14% liable to cause hypoglycaemia. Thirteen percent advocated change to a 'basal-bolus' system of insulin administration. The rest used variants of additional insulin for westward flights and reduced flights eastward. There was great variation in advice, and many regimens were excessively complicated. We recommend simple individualized advice, without attempts at over-zealous glycaemic control during travel. Local arrival and departure times may fit in easily with insulin and meals at standard times before and after flying, and little or no dosage alteration may be needed.

The prediction of the adaptation of circadian rhythms to rapid time zone changes.

The aim of the study was to find out which factors could explain individual differences in the resynchronization speed of circadian rhythms of salivary melatonin and subjective alertness after transmeridian flights over 10 time zones. The mean age of the 40 female subjects was 33.0 +/- 6.9 years. The data were gathered by measurements of the circadian rhythms of melatonin excretion and altertness at 2 h intervals in Helsinki (Finland) two days before westward flight to Los Angeles (USA), where the measurements were repeated on the 2nd day after the flights and on the 2nd day in Finland after return flight. This shift in the acrophases of the two circadian rhythms were used as dependent variables in regression analyses. The predictors used were length of day, marital status, amount of physical exercise, age, neuroticism, extroversion, and eveningness. Age, day length, marital status, and physical exercise explained the acrophase adaptation of the melatonin rhythm after westward flight, and day length, neuroticism, and extroversion after eastward flight. Marital status, neuroticism, and physical exercise explained the variation of the acrophase adjustment of the alertness rhythm after westward flight, and age and eveningness after eastward flight. It is concluded that the amount of daylight and personality are the best predictors of the circadian rhythm adaptation after transmeridian flights.

Effects of midazolam on sleep disturbances associated with westward and eastward flights: Evidence for directional effects

This double-blind parallel groups study investigated the effects of 7.5 mg midazolam on transient insomnia caused by eastward and westward multiple time zone flights. Three groups of six subjects each were treated with either midazolam or placebo during the first four post-flight nights in both directions. Sleep-wake behavior was monitored throughout the study by actigraphic recordings from the wrist of the non-dominant hand in 1 min bins and by morning questionnaires. The results showed that midazolam significantly lengthened sleep and increased the percentages of bins defined as sleep after the eastward flight. These results are discussed in view of recent findings that short-acting benzodiazepines induced phase shifts in mammalian circadian rhythms.

SLEEP AFTER TRANSMERIDIAN FLIGHTS

Nocturnal sleep and daytime sleep latencies, recorded electroencephalographically after westward and eastward flights across the North Atlantic involving time zone shifts of 5 h, were influenced by the time of the flight and by subsequent displacement of the rest period. After the westward flight there was sleep disturbance during the latter part of the first night. However, there was persistent disturbance of sleep after the eastward flight. A rapidly eliminated hypnotic may be useful for the first night or two after a westward flight and for a few nights after an overnight eastward flight.

Effects of "jet lag" on hormonal patterns. III. Demonstration of an intrinsic circadian rhythmicity in plasma prolactin.

The 24-h profile of plasma PRL was obtained by blood sampling at 15-min intervals, and sleep was polygraphically recorded in five normal males, under basal conditions, 1, 11, and 21 days after they travelled from Brussels to Chicago by jet and 1, 11, and 21 days after the return flight. The time difference between Brussels and Chicago was 7 h. Fifteen months later, two of the volunteers were submitted to blood sampling and sleep recording for 48 h after they underwent 33 h of sleep deprivation, mimicking the conditions of the eastward shift without the actual travel. Under basal conditions, the 24-h PRL pattern was bimodal, with a late afternoon elevation and a major nocturnal rise starting shortly after sleep onset and culminating in a midsleep acrophase. Serum PRL levels remained high until awakening, followed by a rapid decline. The 24-h mean PRL level, the ratio of the sleep mean to the wake mean, the value of the nocturnal acrophase, and the number of secretory spikes per 24-h span were not affected by “jet lag” or sleep deprivation, suggesting that these perturbations do not induce alterations in the amount of PRL secreted, even though they were associated with significant disruptions of sleep. One day after the westward flight, a brief elevation in PRL concentration was observed during wakefulness, at the time of the anticipated sleep-associated increase according to Brussels time (anamnestic peak), and the nocturnal PRL acrophase occurred earlier in sleep, with declining levels throughout the rest of the night. Eleven and 21 days after arrival in Chicago, the PRL secretory pattern during sleep had normalized, but anamnestic peaks were still observed. One day after eastward travel, the sleep-related increase in PRL levels was very gradual, reaching its peak only at the anticipated onset of sleep according to Chicago time, and PRL concentrations declined less abruptly after awakening. Full return to the original secretory pattern was observed 11 and 21 days after arrival in Brussels. The 24-h PRL patterns obtained after sleep deprivation were similar to those observed immediately after eastward flight. These results indicate that the nighttime rise of PRL is not solely dependent upon sleep, but also possesses an intrinsic circadian rhythm. (J Clin Endocrinol Metab55: 849, 1982)

Waterbird Migration Near the Yukon and Alaskan Coast of the Beaufort Sea: I. Timing, Routes and Numbers in Spring

Radars, systematic visual observations from the coast, and aerial surveys were used to study migration near the Yukon (1975) and Alaskan (1977-78) coasts of the Beaufort Sea. Conspicuous eastward migration of loons, brant, seaducks, jaegers and glaucous gulls occurs along the icebound coast, and in the Yukon some eastbound species (especially brant) concentrate coastally. Overall, however, eastward migration is predominantly broad-front with little coastal concentration. Most eiders and perhaps most oldsquaws, the commonest waterbirds, fly east offshore where there is more open water. Westward migration is much less conspicuous visually; swans, geese and pintails are the main groups seen. However, radar shows extensive broad-front westward flights, probably largely of shorebirds. Most spring migration, both east and west, is from 15 May to 20 June, with the coastal peak (25 May-15 June) apparently being later than that offshore. Some coastal migrants land on river water that overflows onto nearshore ice in early June. Some waterbirds bypass the largely ice-covered Alaskan Beaufort by flying northeast across interior Alaska and/or northwestern Canada from the Pacific ocean to the Canadian Arctic. These overland migrants include some yellow-billed and arctic loons, brant and jaegers; probably most Thayer's gulls; and probably some oldsquaws, Sabine's gulls, arctic terns and other species.Key words: waterbirds, migration, Beaufort Sea, Alaska, Yukon, radar, aerial surveys, seawatches, leads, leading lines

The effect of real and simulated time-zone shifts upon the circadian rhythms of body temperature, plasma 11-hydroxycorticosteroids, and renal excretion in human subjects.

1. Observations were made upon five subjects who flew through 4(1/2)-6 time zones, four of them returning later to their starting point, and upon twenty-three subjects experiencing simulated 6 or 8 hr time zones shifts in either direction in an isolation unit.2. Measurements were made of plasma concentration of 11-hydroxycorticosteroids, of body temperature, and of urinary excretion of sodium, potassium and chloride. Their rhythm was defined, where possible, by fitting a sine curve of period 24 hr to each separate 24-hr stretch of data and computing the acrophase, or maximum predicted by the sine curve.3. The adaptation of the plasma steroid rhythm was assessed by the presence of a sharp fall in concentration after the sample collected around 08.00 hr. The time course of adaptation varied widely between individuals; it was usually largely complete by the fourth day after westward, and rather later after eastward, flights. After time shift the pattern often corresponded neither to an adapted nor to an unadapted one, and in a subject followed for many months after a real flight a normal amplitude only appeared 2-3 months after flight.4. Temperature rhythm adapted by a movement of the acrophase, without change in amplitude, although on some days no rhythm could be observed. This movement was always substantial even on the first day, and was usually nearly complete by the fifth.5. High nocturnal excretion of electrolyte was often seen in the early days after time shift, more notably after simulated westward flights. Adaptation of urinary electrolyte rhythms usually proceeded as with temperature, but the movement of the acrophase was slower, more variable between individuals, more erratic, and sometimes reversed after partial adaptation. On a few days there were two maxima corresponding to those expected on real and on experimental time.6. Sodium excretion was much less regular than that of potassium, but adapted more rapidly to time shift, so that the two often became completely dissociated. Chloride behaved much as sodium.7. The time course of adaptation of the plasma steroid and urinary potassium rhythms were sufficiently similar to suggest a causal connexion. The time course of adaptation of the temperature rhythm did not coincide with that of any other component considered here.