Influence of polar route schedules on the duty and rest patterns of aircrew

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.

How well do pilots sleep during long-haul flights?

It is imperative that shiftworkers in safety-critical workplaces obtain sufficient sleep to operate effectively. This presents a challenge to long-haul airline pilots who are required to supplement normal bed sleep with sleep on-board an aircraft during flight. In the current study, the sleep/wake behaviour of 301 airline pilots operating long-haul flight patterns was monitored for at least 2 weeks using self-report sleep diaries and wrist activity monitors. The data indicate that sleep opportunities in on-board rest facilities during long-haul flights result in a similar amount of sleep, but only 70% as much recovery, as duration-matched bed sleeps. STATEMENT OF RELEVANCE: This study indicates that in-flight sleep provides airline pilots with 70% as much restoration as duration-matched bed sleep. To increase the restoration provided by in-flight sleep, airlines could take measures to improve the quality, or increase the amount, of sleep obtained by pilots during flights.

Jet lag: therapeutic use of melatonin and possible application of melatonin analogs

Each year millions of travelers undertake long distance flights over one or more continents. These multiple time zone flights produce a constellation of symptoms known as jet lag. Familiar to almost every intercontinental traveler is the experience of fatigue upon arrival in a new time zone, but almost as problematic are a number of other jet lag symptoms. These include reduced alertness, nighttime insomnia, loss of appetite, depressed mood, poor psychomotor coordination and reduced cognitive skills, all symptoms which are closely affected by both the length and direction of travel. The most important jet lag symptoms are due to disruptions to the body's sleep/wake cycle. Clinical and pathophysiological studies also indicate that jet lag can exacerbate existing affective disorders. It has been suggested that dysregulation of melatonin secretion and occurrence of circadian rhythm disturbances may be the common links which underlie jet lag and affective disorders. Largely because of its regulatory effects on the circadian system, melatonin has proven to be highly effective for treating the range of symptoms that accompany transmeridian air travel. Additionally, it has been found to be of value in treating mood disorders like seasonal affective disorder. Melatonin acts on MT(1) and MT(2) melatonin receptors located in the hypothalamic suprachiasmatic nuclei, the site of the body's master circadian clock. Melatonin resets disturbed circadian rhythms and promotes sleep in jet lag and other circadian rhythm sleep disorders, including delayed sleep phase syndrome and shift-work disorder. Although post-flight melatonin administration works efficiently in transmeridian flights across less than 7-8 times zones, in the case longer distances, melatonin should be given by 2-3 days in advance to the flight. To deal with the unwanted side effects which usually accompany this pre-departure treatment (acute soporific and sedative effects in times that may not be wanted), the suppression of circadian rhythmicity by covering symmetrically the phase delay and the phase advance portions of the phase response curve for light, together with the administration of melatonin at local bedtime to resynchronize the circadian oscillator, have been proposed. The current view that sleep loss is a major cause of jet lag has focused interest on two recently developed pharmacological agents. Ramelteon and agomelatine are melatonin receptor agonists which, compared to melatonin itself, have a longer half-life and greater affinity for melatonin receptors and consequently are thought to hold promise for treating a variety of circadian disruptions.

Eastward long distance flights, sleep and wake patterns in air crews in connection with a two-day layover

The present study describes the spontaneous sleep/wake pattern in connection with an eastward (Stockholm to Tokyo, +8 h) transmeridian flight and short (51 h) layovers. To describe all sleep episodes and the recovery process across 4 days, and to relate adjustment to individual differences, 49 Scandinavian Airlines System (SAS) air crew were monitored for 9 days with activity monitors and sleep/wake diary before-during-after flight. The outbound flight involved a period of wakefulness extended to 21 h, frequently (87% of air crew) terminated by a long nap in Tokyo which was calm but difficult to wake up from. Then followed two night oriented sleep periods of normal length but of reduced efficiency, containing many and long awakenings. Napping was common during the extended periods of wakefulness, particularly during flights. During the recovery days, ease of rising from sleep in the mornings was difficult throughout, and feelings of not being refreshed returned to baseline levels on the third recovery sleep. Elevated daytime sleepiness (24% of the day) was observed on the first recovery day. No individual differences related to gender, age or position (cabin/pilot) was found in sleep strategy. Poor adjusters, subjects with a perceived lowered capacity on recovery days, showed more premature awakenings abroad and less refreshing sleep during the last 12 months, suggesting a decreased ability to cope with air crew scheduling. Comparisons with a westbound flight showed the eastbound flight layover sleep to be more problematic and containing more napping.