Biomedical subjects

Barbara Griefahn

Publications and source records attributed to Barbara Griefahn.

18 recordsLinked to original sources

PubMed2006

Executive brain functions after exposure to nocturnal traffic noise: effects of task difficulty and sleep quality.

The after-effects of nocturnal traffic noise on cognitive performance and inhibitory brain activity were investigated. Twenty participants (18-30 years) performed an easy and a difficult visual Go/Nogo task with simultaneous EEG recording after a quiet night and then during three nights when aircraft noise was presented with equivalent noise levels of 39, 44, and 50 dBA, respectively, between 11 p.m. to 7 a.m. Based on subjective sleep quality rating, participants were separated into "good" versus "bad" sleepers. The performance and inhibition-related components (N2, P3) of event-related potentials were analysed. The N2 and P3 amplitudes were smaller and latencies were prolonged in the difficult than in the easy task. This effect was more pronounced for Nogo than for Go trials. The Nogo-P3 amplitude was smaller in Noise than in "Quiet" conditions in the difficult task only. In the difficult task, the Nogo-P3 latency was prolonged in bad sleepers than in good sleepers. The Nogo-P3 amplitude was reduced in Noise as compared to "Quiet" conditions in bad sleepers only. Sleep quality in bad sleepers worsened steadily with increasing noise levels. No effects of noise or subjective sleep quality on performance were found. Inhibitory processes appear to be selectively impaired after nocturnal noise exposure. The task difficulty and perceived sleep quality are important factors modulating noise effects. The results suggest that nocturnal traffic noise increase physiological costs for inhibitory functioning on the day even if no overt performance decrement is observed.

Action Potentials↗

PubMed2006

Shifts of the hormonal rhythms of melatonin and cortisol after a 4 h bright-light pulse in different diurnal types.

If applied during corresponding times of the individual melatonin profiles, bright light shifts the circadian phase equally, irrespective of diurnal type. We examined 32 young men: 10 morning types, 11 evening types, and 11 with no predisposition; 16 with high and 16 with low melatonin production. Each completed a 40 h session that included two consecutive nights during which the participants remained, apart from two short breaks during the second day, in bed under an illumination level of 30 lux. A 4 h bright light pulse was applied just after the expected individual melatonin onset the first night to cause a delay of the hormonal profile the second night. Salivary levels of melatonin and cortisol were determined hourly. Melatonin was delayed by 108 min, and cortisol offset and onset by 47 and 110 min, respectively. The cortisol quiescent period (start and end of the quiescent period being defined by the decrease below and the increase above 60% of the average cortisol production between 18:00 and 09:00 h) was prolonged. In contrast to the other subgroups, the delay of melatonin synthesis was about 0.5 h shorter in morning types, and their cortisol quiescent period was shortened. The present study leads to the hypothesis that, despite individually scheduled light exposure, morning types are potentially disadvantaged due to elevated cortisol levels, if persisting, in career night workers.

Adolescent↗

PubMed2005

After effects of noise-induced sleep disturbances on inhibitory functions.

The study focuses on possible after effects of noise-induced sleep disturbances on inhibitory brain processes reflecting in performance changes and alternations of inhibition-related components of event-related potentials (ERPs). Following a quiet night and three nights, in which railway noise was presented with different levels, twelve women and ten men (19-28 years) performed a visual Go/Nogo task that contained stimuli either compatible or incompatible with a response. Noise-induced sleep disturbances are highly evident in worsening of subjective sleep quality but did not show up in significant changes of reaction time and error rate. A smaller N2 amplitude and longer latency to incompatible than to compatible stimuli as well as an unspecific attenuation of N2 amplitude under Noise were found. The amplitude of the fronto-central P3 was reduced under Noise compared to baseline only in Nogo trials. The amplitude of the parietal P3 in Go trials was smaller to incompatible than to compatible stimuli but was not affected by Noise. Disturbed sleep was associated with a decreased blink rate during task performance. The results suggest that physiological costs to maintain performance are increased after noisy nights. Decisional processes underlying overt responses (Go-P3) are less vulnerable to noise-disturbed sleep than those related to inhibition (Nogo-N2, NoGo-P3). The deficits may have been compensated by increased on-task concentration and thereby did not become apparent in the performance data. Inhibition-related ERPs may be more sensitive indicators of moderate sleep disturbances caused by noise than performance measures.

Adult↗

PubMed2004

Do birth variable data predict melatonin production in 8- to 9-year-old children? Analysis of excreted 6-sulfatoxymelatonin.

HYPOTHESES: A cross-sectional study on urinary excretion of 6-sulfatoxymelatonin (aMT.6S) in young adults suggests a relation between melatonin production and body size at birth. As individual melatonin production remains stable during childhood and adolescence, this melatonin-birth size relation should also exist in children. METHODS: Daily urinary output of aMT.6S of 147 healthy white children (78 boys, 69 girls), 8 or 9 years of age, was quantified by ELISA and related to birth variable data. RESULTS: Contrary to expectation, aMT.6S output was not related to the ponderal index at birth but a moderate positive association with body mass index at the age of 8-9 years was seen. CONCLUSION: This study in children contradicts previous findings in adults. As no obvious reason can be identified for this discrepancy, further research (particularly a longitudinal study) is recommended to clarify whether birth variable data may predict melatonin production in certain circumstances during or after puberty.

Birth Weight↗

PubMed2003

Evaluation of performance and load in simulated rescue tasks for a novel design SCBA: effect of weight, volume and weight distribution.

A self-contained breathing apparatus (SCBA) with an innovative rucksack shape that provides a better distribution of its weight over the middle and lower parts of the back (device C: 6l, 13.7 kg) was compared with two conventional SCBA which differed from each other in volume and weight (A: 6l, 15 kg, B: 6.8l, 11.7 kg). Twelve fire-fighters (27-49 yr) performed three exercises while using the three SCBA in a systematically permuted sequence. The exercises consisted of simulated rescue work under natural climatic conditions in a dwelling on the second floor and several typical elements of severe fire-fighting actions. Duration, heart rate, breathing frequency, rectal temperature, and sweat loss were recorded. Perceived exertion was rated and the carrying features of the SCBA were subjectively evaluated. The exercise was executed faster with the rucksack device, heart rates were then lower and the carrying features were evaluated as better. Thus, the weight of the SCBA was shown to be less important than its distribution.

Adult↗

PubMed2003

Melatonin production during childhood and adolescence: a longitudinal study on the excretion of urinary 6-hydroxymelatonin sulfate.

Cross-sectional data on urinary 6-hydroxymelatonin sulfate (6-OHMS) excretion in children suggest a constant melatonin secretion during growth. The present longitudinal study concerned, accordingly, the intra-individual stability of melatonin production during childhood and adolescence. Urine samples collected during a longitudinal investigation of healthy white children and adolescents were analyzed. Forty-six boys and 38 girls were chosen for the present study. They had passed 3-15 annual examinations between their 3rd and 18th yr of age. Each examination included the collection of urine over 24 hr. The daily urinary output of 6-OHMS of the overall 621 samples was quantified by enzyme-linked immunosorbent assay. The analyses clearly revealed for the first time that, despite huge inter-individual differences, melatonin production remains constant in one and the same individual during childhood and adolescence. Additionally, neither a significant sex difference was observed nor was the 6-OHMS output affected by season. The dramatic decrease of plasma melatonin levels as described in the literature is mainly related to an increase in body size rather than to decreasing pineal secretion.

Adolescent↗

PubMed2003

Excretion of 6-hydroxymelatonin sulfate (6-OHMS) in siblings during childhood and adolescence.

The analysis was performed to support the assumption that in inter-individual variations melatonin production is determined genetically. Sixty-six siblings from 31 families (27 girls, 39 boys, 3-18 years) contributed to this study with 3 to 15 urine samples collected once a year over 24 h. The samples were stored at -20 degrees C and analyzed for the daily output of the melatonin metabolite 6-hydroxymelatonin sulfate (6-OHMS) by an enzyme-linked immunosorbent assay (ELISA). The results indicate that 6-OHMS excretion was significantly correlated in siblings (r = 0.37, p = 0.01), suggesting a possible genetic background of melatonin production. However, prospective studies controlling also lifestyle factors such as diet are required to further confirm the hypothesis.

Adolescent↗

PubMed2003

The reliability of melatonin synthesis as an indicator of the individual circadian phase position.

Melatonin synthesis occurs earlier in the morning than in the evening types who strictly adhere to their individual time schedule. This study tested whether melatonin profiles still separate between diurnal types who vary their individual rhythm or who are submitted to prescribed time schedules. Male and female students were observed during a constant routine in the laboratory (24-26 hours bed rest, 20 degrees C, <30 lux, hourly isocaloric diet) and soldiers who spent several days in a military hospital were observed during 12 hours (bed rest, <30 lux, normal meals). Salivary melatonin levels were determined hourly. In both studies, melatonin profiles occurred earlier in the morning than in the evening types. The difference was smaller in soldiers, thus conditioning contributes to the actual phase position but does not mask morningness. As morningness is related to the ability to cope with shift work, the melatonin onset can be used as a criterion when assigning a person to shift work.

Adolescent↗

PubMed2002

Evaluation of draught in the workplace.

During 826, 1-h sessions 107 participants (33 women, 74 men, 18-51 years of age) were exposed to defined draughts where air velocity (0.1 < or = V(a) < or = 0.4 m s(-1)), turbulence intensity (< 30, approximately equal to 50, > 70%), draught direction (horizontal, vertical, diagonal), air temperature (11 < or = t(a) < or = 23 degrees C), and metabolic rate ( approximately equal to 60< or = M < or = 156 W m(-2)) were varied but kept constant during single sessions. Perception and evaluation (annoyance due to draught and local cold) were registered using a list of prescribed body parts. Annoyance due to draught increased with the increase in mean air velocity and in turbulence intensity, as well as with the decrease in air temperature and in metabolic rate. The direction of air flow had no influence. As these responses were neither sufficiently predicted by the draught-rating model proposed in ISO 7730 (1994), nor by its extension developed by Toftum (1994a), the latter was modified according to the data registered in this paper. Using the modified model the accordingly predicted percentage of people annoyed by draught agreed highly with the percentage actually observed (r=0.726, p<0.001). As the resulting model covers larger ranges of air temperature and metabolic rate it is suggested that it should substitute the model proposed in ISO 7730 [1994].

Adolescent↗

PubMed2002

Melatonin synthesis: a possible indicator of intolerance to shiftwork.

HYPOTHESIS: Melatonin synthesis, which is directly controlled by the central circadian pacemaker indicates the circadian phase better than rectal temperature. METHODS: Thirty four men (16-32 years, 7 morning, 13 neither, 14 evening types) performed a constant routine (24-26-hr bedrest, < 30 lux, 18-20 degrees C, hourly isocaloric diet). Salivary melatonin level was determined hourly and rectal temperature was continuously recorded. RESULTS: The nadir of rectal temperature occurred 1.5 hr (P = 0.017), the onset of melatonin synthesis 3 hr earlier (P < 0.0001) in morning than in evening types. Morningness was not related to the quantitative but significantly to the temporal parameters, closer to those of melatonin than of rectal temperature. CONCLUSIONS: The melatonin onset is a more reliable indicator of the diurnal type than the nadir of rectal temperature. As morningness has been associated with intolerance to shiftwork, melatonin profiling provides a suitable basis for the establishment of directed preventive measures.

Adaptation, Physiological↗

PubMed2002

Experiments on effects of an intermittent 16.7-Hz magnetic field on salivary melatonin concentrations, rectal temperature, and heart rate in humans.

OBJECTIVES: The present experiments concerned the hypothesis that an intermittent, strong and extremely low frequency magnetic field reduces salivary melatonin levels and delays consecutively the nadirs of rectal temperature and heart rate. METHODS: Twelve healthy young men (18-25 years) participated in three randomly permuted sessions, which were performed as constant routines. The participants kept a strict bed rest over 26 h, air temperature was 20 degrees C, illumination < 30 lx, and sound level < 50 dBA. Salivary melatonin levels were determined hourly, rectal temperature and heart rate were registered continuously throughout. An intermittent magnetic field was administered in one session from 6 p.m. to 2 a.m. at 16.7 Hz, 0.2 mT and alternating on/off-periods of 15 s. This situation was compared with a control session without any additional stress. Another session was performed to determine the participants' ability to respond to a well-known melatonin-suppressing stress, namely bright light (1,500 lx, 10 p.m.-2 a.m.). RESULTS: Bright light inhibited melatonin synthesis in all 12 participants and delayed the nadirs of rectal temperature and heart rate. The only significant alteration that was associated with exposure to the magnetic field was a delay in the heart rate nadir, which was not mediated by an accordingly altered melatonin profile. CONCLUSION: The fact that the circadian rhythm of only the heart rate was altered indicates an internal dissociation which might constitute a health risk in the long run and needs to be investigated more extensively.

Adult↗

PubMed2002

The validity of the temporal parameters of the daily rhythm of melatonin levels as an indicator of morningness.

The present study tested the assumption that the temporal parameters of melatonin synthesis indicate the individual circadian phase position better than the minimum of rectal temperature. Thirty-four men and 17 women (16-32 yr, 14 morning, 14 neither, 23 evening types) completed a constant routine (24-26 h bedrest, <30 lux, 18-20 degrees C, hourly isocaloric diet). Salivary melatonin level was determined hourly, rectal temperature and heart rate were continuously recorded throughout. The minima of rectal temperature and heart rate as well as the temporal parameters of melatonin synthesis occurred earlier in morning than in evening types and were significantly related to the subjective circadian phase as determined by the morningness-eveningness questionnaire. The level of significance and the resolving power was greater for the melatonin parameters and for the minimum of heart rate than for the minimum of rectal temperature. The temporal differences between the opposite diurnal types were larger and the correlation coefficients with morningness were higher in men than in women. The temporal parameters of melatonin synthesis are valid indicators of the individual circadian phase. As morningness is closely related to the ability to cope with shiftwork, the determination of the melatonin profile might be a valuable element of the criteria when assigning a person to shiftwork.

Adolescent↗

PubMed2002

Effects of electromagnetic radiation (bright light, extremely low-frequency magnetic fields, infrared radiation) on the circadian rhythm of melatonin synthesis, rectal temperature, and heart rate.

Electromagnetic spectra reduce melatonin production and delay the nadirs of rectal temperature and heart rate. Seven healthy men (16-22 yrs) completed 4 permuted sessions. The control session consisted of a 24-hours bedrest at < 30 lux, 18 degrees C, and < 50 dBA. In the experimental sessions, either light (1500 lux), magnetic field (16.7 Hz, 0.2 mT), or infrared radiation (65 degrees C) was applied from 5 pm to 1 am. Salivary melatonin level was determined hourly, rectal temperature and heart rate were continuously recorded. Melatonin synthesis was completely suppressed by light but resumed thereafter. The nadirs of rectal temperature and heart rate were delayed. The magnetic field had no effect. Infrared radiation elevated rectal temperature and heart rate. Only bright light affected the circadian rhythms of melatonin synthesis, rectal temperature, and heart rate, however, differently thus causing a dissociation, which might enhance the adverse effects of shiftwork in the long run.

Adolescent↗

PubMed2002

Night-time Noise Annoyance: State of the Art.

The annoyance-reaction is one of the central variables in noise research. After an introduction to different concepts and definitions of noise annoyance different scales of how noise annoyance can be measured are shown. The question is discussed whether disturbance effects of noise at different times of day are given. To clarify this problem, the results of a series of actual German noise studies are reported. In these studies differences between day- and night-time annoyance are found depending on the sound sources. For the case of road traffic noise no differences between day and night-time annoyance were found. In contrast, annoyance reactions are related to the time of day for railway and air traffic noise. Especially for aircraft noise, above a Leq of 50 dB(A) night-time annoyance rises faster than day-time annoyance. The effects are discussed in the frame of a cognitive model of noise annoyance. It is argued that annoyance judgements are based on an internal representation of the noise situation. Part of this representation are the event characteristics of the sound sources and their estimated impacts for disturbances at different times of day.

Journal Article↗

PubMed2002

Sleep Disturbances Related to Environmental Noise.

The permanently open auditory channel and the ability of the brain to process incoming acoustical stimuli even while asleep and to respond adequately is the essential precondition for noise-induced sleep disturbances which are regarded as the most deleterious effects of noise. In the past, research was mainly focused on the detection and description of the various effects of noise, on the influence of personal and environmental factors, on the determination of dose-response relations and the definition of critical noise loads, above which noise becomes intolerable. These limits are, however, as yet only tentative or applicable for a very few situations and need to be verified or revised. The present paper is focused on the priorities for future research. These are in particular 1) the causal linkage between environmental noise, primary and secondary effects on the one hand and the hypothesized contribution to multifactorial chronic diseases, to chronic annoyance, and to permanent behavioural alterations on the other hand, 2) the identification of the causes for the great discrepancies between the small effects determined in the field and the large responses recorded in the laboratory, 3) temporal aspects such as sleep at unusual times (day sleep after nightshifts), definition of night-time and day-time, 4) the significance of the shoulder hours for subsequent sleep, 5) the individual vulnerability, 6) the accumulation of data from different studies.

Journal Article↗

PubMed2000

Physiological, subjective, and behavioural responses during sleep to noise from rail and road traffic.

An interdisciplinary study was performed to examine the difference between road and rail traffic noise with regard to physiological, subjective, and behavioural responses. In 8 areas where either rail or road noise prevailed, a total of 1 600 persons (18 to 70 years of age) were interviewed; a subgroup of 377 persons was examined during 2 times 5 nights each. In this sleep observation period noise impact and body movements were recorded continuously during each night. Every morning the subjects stated the position of the windows during the night, they evaluated the qualitative and quantitative parameters of sleep and performed a 4-choice reaction time test. Only the behaviour to sleep with open or closed windows was significantly associated with the rating level and the windows were significantly more often closed by the residents primarily exposed to road noise. Whether this indicates a reaction to noise or to concomitant pollutants such as odour is, however, debatable. The fact that none of the other data recorded here revealed any difference between the two types of noise is discussed in view of future studies.

Journal Article↗

PubMed1996

Human Adaptation to Work in Two Different Climates.

The processes of acclimation to hot-dry and to warm-humid climates were studied using two approaches: a quantitative analysis of literature data and an experimental study in the laboratory concerning the physiological parameters of heart rate, rectal temperature, sweat loss, and subjective assessment. Analysis o f literature data: Data from 62 experiments with a total of 813 participants were pooled and recalculated. The experiments ranged from 6 to 24 days, air temperatures from 30.4 to 50.0°C, water vapor pressures from 1.5 to 6.5 kPa, and wet bulb globe temperatures (WBGT) from 27.4 to 38.6°C. Laboratory studies: In the laboratory, 8 participants were acclimated during 15 consecutive days to a hot-dry climate and to a warm-humid climate, which were equivalent in terms of the WBGT (33.5 and 33.6°C, respectively). The participants walked four times for 25 min on a treadmill at a speed of 4 km/h. The hot-dry climate caused somewhat greater strain than the warm-humid condition. In the course of acclimation to the hot-dry climate, heart rate and rectal temperature started at higher levels, decreased slightly steeper but remained on a higher level throughout. Nevertheless, the differences between both thermal conditions were small, and both physiologic functions reached the point of acclimation almost at the same time under warm-humid and under hot-dry exposure. Sweat loss, which is not regarded as a valid predictor for acclimation, was considerably higher but increased less in the hot-dry than in the warm-humid climate.

acclimation↗

PubMedDate not supplied

Evaluation criteria for aircraft noise.

Based on extensive and detailed reviews the present paper suggests evaluation limits for aircraft noise for the prediction of noise effects and for the protection of residents living in the vicinity of (newly constructed or extended) civil airports. The protection concept provides graded assessment values: Critical Limits indicate noise loads that shall be tolerated only exceptionally during a limited time. Protection Guides are central assessment values for taking actions to reduce noise imission. Threshold values inform about measurable physiological and psychological reactions due to noise exposures where long term adverse health effects are not expected. Evaluation limits are provided for various protection goals. Apart from hearing damage, evaluation limits are provided for the avoidance of primary extraaural effects on communication and on sleep, for the avoidance of annoyance as a secondary effect and for the avoidance of suspected cardiovascular diseases. Such limits enable authorities to outline the areas around airports, where appropriate measures are mandatory to protect residents against the deleterious effects of noise. Protecting residents is a dynamic process that must be followed up. The evaluation limits must be repeatedly tested in view of new scientific findings and adapted, if necessary.

Aircraft↗