Alexander Samel

Aircraft noise effects on sleep: Application of the results of a large polysomnographic field study

The Institute of Aerospace Medicine at the German Aerospace Center (DLR) investigated the influence of nocturnal aircraft noise on sleep in polysomnographic laboratory and field studies between 1999 and 2004. The results of the field studies were used by the Regional Council of Leipzig (Germany) for the establishment of a noise protection plan in the official approval process for the expansion of Leipzig/Halle airport. Methods and results of the DLR field study are described in detail. Special attention is given to the dose-response relationship between the maximum sound pressure level of an aircraft noise event and the probability to wake up, which was used to establish noise protection zones directly related to the effects of noise on sleep. These protection zones differ qualitatively and quantitatively from zones that are solely based on acoustical criteria. The noise protection plan for Leipzig/Halle airport is presented and substantiated: (1) on average, there should be less than one additional awakening induced by aircraft noise, (2) awakenings recalled in the morning should be avoided as much as possible, and (3) aircraft noise should interfere as little as possible with the process of falling asleep again. Issues concerned with the representativeness of the study sample are discussed.

CHRONOBIOTIC EFFECTS OF THE MELATONIN AGONIST LY 156735 FOLLOWING A SIMULATED 9H TIME SHIFT: RESULTS OF A PLACEBO-CONTROLLED TRIAL

Introduction: The melatonin agonist LY 156735 (LY) is a new investigational drug under development to treat circadian rhythm disorders. The present study assessed the efficacy of LY to alleviate the symptoms of shift lag and to enhance readaptation of desynchronized circadian rhythms to a new time zone. Subjects and methods: Eight healthy male volunteers of age 25–35 yr participated in three identical trials of 13d duration in a temporal isolation unit separated by washout intervals. A high dose (HD) of 5 mg and a low dose (LD) of 0.5 mg of LY and placebo (PL) were administered double-blinded in a three-period cross-over design. Each trial consisted of an adaptation period, a pre-shift period for baseline measurements, a simulated 9h phase-advance shift, and a post-shift period for follow-up. The time shift was performed at 23:00h of day 6 by advancing the laboratory time to 08:00h of day 7. Double-blind study medication was administered at 14:30h on day 6, and at 22:30h on days 7–10. Subjective ratings of jet lag, alertness, tenseness, and daytime fatigue were assessed using visual analog scales (VAS) and standardized questionnaires. The objective markers of readaptation included core body temperature, wrist actigraphy, cortisol and electrolyte excretion, and a battery of computerized performance tests. Results: HD but not LD enhanced the readaptation speed of all physiological rhythms investigated, as demonstrated by a significantly faster movement of acrophases towards the post-shift target time. HD (p=0.05) significantly blunted the post-shift deterioration of performance in those tests that were sensitive to shift lag. Parameters of subjective well-being were not significantly affected by either dose. Conclusion: This pilot study demonstrates the chronobiotic efficacy of LY when taken at a dose of 5 mg/d.

Bright Light: a Countermeasure for Jet Lag?

After time-zone flights, the environmental time is shifted abruptly. The sleep-wake cycle and the circadian system cannot follow this sudden phase shift. Therefore, some or several days are necessary to achieve complete adjustment to a new time zone. The effects resulting from the displacement between internal and external time are well known as jet lag. In principle, timed bright light is able to enhance the resynchronization process of the circadian system after advance or delay shifts. In this report, the effects of bright light exposure on circadian phases and amplitudes after real or simulated time zone transitions are reviewed from the accessible literature and are critically discussed. It can be concluded that laboratory studies have not been unequivocally successful to support the hypothesis that bright light alleviates jet lag. The sparse number of field studies do not yet allow a clear judgment on the beneficial effect of bright light treatment on jet lag.

Performance impairment during four days partial sleep deprivation compared with the acute effects of alcohol and hypoxia

OBJECTIVE Subjects were exposed to cumulated partial sleep deprivation (psd), alcohol intake and hypoxia in a sequential design to examine the impact on neurobehavioral performance. METHODS Sixteen healthy male volunteers were enrolled in this study and were exposed in turn, after adaptation and baseline measurements, to one day of periods of hypoxia, one day of alcohol intake and one day for recovering (with 8h time in bed TIB). Subsequently the exposition of those conditions is that the subjects spent 5h night restriction daily for four consecutive days, followed by two recovery days. Performance was tested five (or six) times per day with reaction time task (SRT) and unstable tracking task (UTT). RESULTS The performance impairment showed to be cumulative in both tests over the four sleep deprivation days and differed significantly from baseline. Corresponding performance deficits under the influence of the stressors were for SRT: four days psd, 13% O(2) concentration and a blood alcohol concentration (BAC) of around 0.4-0.6 per thousand for UTT: four days psd, 13% O(2) concentration and a BAC of around 0.6 per thousand. One night of 8h sleep restored performance nearly to baseline level. CONCLUSIONS A sleeping time of 5h per night for four consecutive days impairs performance in such a way that traffic safety may be compromised.

Auswirkungen von nächtlichem Fluglärm - Forschung und Anwendung am Beispiel des Flughafens Leipzig/Halle

Das Flugverkehrsaufkommen steigt kontinuierlich an. Einerseits wird durch die Luftfahrt das Mobilitatsbedurfnis der Menschen fur sich und ihre Guter erfullt. Andererseits hat der Flugverkehr auch negative Seiten. So wird besonders der durch den Flugbetrieb erzeugte Larm von der Bevolkerung in der Umgebung von Flughafen als sehr unangenehm empfunden. Das gravierendste Problem sind Schlafstorungen durch nachtlichen Fluglarm. Mit einer umfangreichen Studie zum Einfluss von Nachtfluglarm auf den Schlaf hat das Institut fur Luft- und Raumfahrtmedizin des Deutschen Zentrums fur Luft- und Raumfahrt (DLR) wichtige neue Erkenntnisse gewonnen. Die daraus abgeleiteten Schutzkriterien werden beim Ausbau des Flughafens Leipzig/Halle sowohl zum Nutzen der Betroffenen als auch der Verursacher von Fluglarm angewendet.