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Biomedical subjects

P Knauth

Publications and source records attributed to P Knauth.

At least 37 records · Page 2Linked to original sources
PubMed1988

Work at sea: a study of sleep, and of circadian rhythms in physiological and psychological functions, in watchkeepers on merchant vessels. VI. A sea trial of an alternative watchkeeping system for the merchant marine.

A trial of an alternative to the traditional 4-on/8-off watchkeeping system was made on a container ship during a round trip from Europe to the Far East. The three navigating officers on the ship operated the new system, which involved "compressed" working hours with a long unbroken period of rest, during two sections of the voyage, one of which included six stops at ports. Despite unforeseen problems arising mainly from these stops, questionnaire responses concerning the new system were not altogether unfavourable to it, and daily records kept by the officers gave some support to the hypothesis that sleep would be better than under the traditional system. However, a number of difficulties were encountered; these are discussed in relation to the design of future studies of alternative watchkeeping systems.

Circadian Rhythm↗
PubMed1988

Work at sea: a study of sleep, and of circadian rhythms in physiological and psychological functions, in watchkeepers on merchant vessels. I. Watchkeeping on board ships: a methodological approach.

The safety of a ship depends substantially on its bridge watchkeepers, whose alertness and efficiency must be maintained at all hours of the day and night. Fatigue, circadian rhythms, and sleep disruption occasioned by the unusual working hours of these personnel may all affect their performance. A methodology for assessing the magnitude of this problem is proposed. The application of this methodology in a large-scale shipboard study of merchant mariners on extended voyages is then described, and details given of the techniques used to measure sleep and activity, and temporal variations in a range of physiological und psychological parameters. A summary of the data collected in the study is provided as a reference point for the reports on the different aspects of the results that follow in subsequent articles.

Body Temperature↗
PubMed1988

Work at sea: a study of sleep, and of circadian rhythms in physiological and psychological functions, in watchkeepers on merchant vessels. II. Sleep duration, and subjective ratings of sleep quality.

Sleep length and sleep quality scores were collected on board ships over periods of up to two weeks from 38 watchkeepers working a '4-on/8-off routine' and 29 dayworkers. All watchkeepers exhibited fragmented sleeping patterns, which indicated a lack of adaptation of the sleep/wakefulness cycle to the hours of work. There were only slight differences in total sleep length between watchkeepers and dayworkers, however, both groups did not obtain an adequate amount of sleep. Within the watchkeeping crews the 3rd Officers had by far the shortest sleep length. Concerning sleep quality, daytime sleep was generally given the lowest ratings, whereas sleep starting before midnight was on average evaluated as the best, both by watchkeepers and dayworkers. Watchkeeping personnel do not normally have any "days off" during a voyage so that missed sleep might even amount to a sleep deficit. A solution for this problem could perhaps be a new, stabilized system that allows a single uninterrupted sleep, which is required for full recuperation, to be taken each day.

Circadian Rhythm↗
PubMed1988

Physical fitness and other individual factors relating to the shiftwork tolerance of women.

Maximal oxygen consumption (VO2max), muscle strength (MS) and physical activity were compared to age, shiftwork experience, morningness, personality traits and social factors intervening in the shiftwork tolerance of 128 women. The subjects were nurses and nursing aids working irregular shifts in a hospital. Neuroticism was the most powerful negative factor connected to higher fatigue and various symptoms of the subjects. High VO2max and good MS were, on the other hand, the most important positive factors connected to lower fatigue and musculoskeletal symptoms and better sleep quality of the subjects. In different shifts, fatigue, sleep length and quality were influenced most by morningness. It is concluded that physical fitness is an important individual factor explaining the variations of shiftwork tolerance in women.

Adult↗
PubMed1986

Algorithms for the computerised construction of shift systems which meet ergonomic criteria.

A search algorithm is presented to generate all shift systems according to a given set of constraints, including physiological and social requirements. The generated shift systems are weighted according to such criteria as the time distribution of the shifts, the length of the weekend leisure time and the regularity of the shift system. The use of this algorithm is restricted to the construction of shift systems for a maximum of five crews, as is usual in industry. A heuristic algorithm for the construction of more complex shift systems, as used in the services sector, is also described. The user of the program may consider all criteria simultaneously. He must assign priorities to the criteria according to his wishes.

Journal Article↗
PubMed1984

Adjustment of the oral temperature rhythm to a fixed watchkeeping system on board ship.

Oral temperature data were collected from 12 members of the crew of an oil tanker at sea. Most of the personnel examined were engaged on watchkeeping duties on a '4 on, 8 off' fixed-hours system; the remainder included 3 "day-workers". The study commenced after the subjects had been following their particular work schedules continuously for several weeks, thus providing good opportunity for adaptation to them. Observations were made at 4-hourly intervals during waking hours, over a period ranging from 8 to 13 days in individual cases. The form of the mean curves produced by averaging the readings over all days indicated that a reasonable degree of adjustment of the temperature rhythm to the different sleep/wake routines imposed by the work system had occurred. Estimates of rhythm phase and amplitude obtained by "single cosinor" time series analyses of the sequential data supported this impression. However, further investigations are needed to substantiate these findings, and also to determine how long it takes for the rhythm adjustment process to reach completion in inexperienced workers.

Body Temperature↗
PubMed1983

Reduction of nightwork by re-designing of shift-rotas.

The reduction of nightwork is an important preventive measure to limit possible negative effects of night shifts on well-being, health and social life. An example of a gradual reduction of nightwork in a group of transport workers at an airport is presented. After having carefully analysed the real number of persons needed during nighttime for loading and unloading aircrafts the number of shiftworkers who had to work between 02.00 and 06.00 h was reduced in a first step from 104 to 66 and in a second step to 38 persons.

Aircraft↗
PubMed1983

Time-budget studies of policemen in weekly or swiftly rotating shift systems.

For 8 days 120 policemen kept special diaries including working time, travelling to and from work, leisure time and sleeping time. By analysing the data of leisure and sleep in relation to the time of day and the type of shift it is possible to find out critical points within a shift system. The mean duration of sleep was reduced before morning shifts, between night shifts and after a morning shift that was followed by a night shift on the same day. The leisure time was limited in connection with afternoon shifts and between the combined morning and night shift. It is recommended not to have double shifts on one day. Rapidly rotated shift systems had more advantages referring to the total amount of night sleep than weekly rotated shift systems. The backward rotation of shifts was unfavourable because of the short time off between the last afternoon shift and the first morning shift. Furthermore, short nightwork periods and a start of the morning shift which is not too early seem to be preferable.

Journal Article↗
PubMed1983

Analysis of 120 shift systems of the police in the Federal Republic of Germany.

120 shift rotas of the police were collected and analysed. The frequency distribution of the shift cycles, the duration of shifts, the start and end of shifts, the maximal number of consecutive night shifts, as well as the frequency of different kinds of free weekends, were determined. The shift systems are compared with recommendations for the design of shift rotas which are based on physiological, psychological and social criteria.

Journal Article↗
PubMed1979

Systematic selection of shift plans for continuous production with the aid of work-physiological criteria.

Taking into account the numerous theoretically possible shift systems, we chose sensible shift systems with the aid of objective work-physiological criteria, eg, the duration of the daily working time, the positioning and duration of sleep and recreation time. With an agreed 40 h week shift, systems with a weekly working time of 42 h are more advantageous. If the shifts are equally attended over 24 h the following shift systems are recommended: when you have 8 h shifts the relation between the number of working days and the number of free days should be "3 n/n", whereby n must be larger than 1, within one shift rota. In the exceptional case of a 12 h shift the corresponding relation should be "2 n/n". Further unsuitable and recommended shift plan examples are demonstrated for these shift systems.

Journal Article↗