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Biomedical subjects

A Knutsson

Publications and source records attributed to A Knutsson.

12 recordsLinked to original sources
PubMed1991

Manifest sleepiness and the spectral content of the EEG during shift work.

Twenty-five three-shift workers in a process industry were subjected to ambulatory polysomnography during one afternoon and one night shift. The electroencephalographic (EEG) recordings were analyzed with spectral analysis. Subjective sleepiness increased during the night work but did not reach an extreme level. Five subjects fell asleep during night work and the involuntary naps were preceded by a few minutes of increased alpha (8-11.9 Hz) power density. Alpha and theta activity occurred in very short bursts. The hourly mean EEG alpha power density increased significantly but moderately during the night shift and correlated with subjective ratings of sleepiness. Theta power density (4-7.9 Hz) did not increase during the night shift, nor did it correlate with subjective sleepiness. It was suggested that the shift workers could prevent much of the polysomnographic manifestations of sleepiness by various types of activity (including succumbing to sleep). It was also suggested that averaging power density values across long time periods might not be an optimal strategy for detection of sleepiness, but rather some method of emphasizing the occurrence of alpha or theta bursts.

Adult↗
PubMed1991

Spectral analysis of sleep electroencephalography in rotating three-shift work.

Fourteen male rotating three-shift workers were subjected to 24-h ambulatory polysomnographic recording in connection with morning, afternoon, and night shift work (at home and at work). Total sleep time, stage 2, rapid-eye-movement sleep, and slow-wave sleep (stages 3 + 4) were significantly reduced during sleep in connection with the night and morning shifts. Other visually scored sleep parameters and slow-wave energy (spectral power density integrated across sleep) were not affected. The content of the sleep cycles did not differ between shifts. The sleep before the morning shift was characterized by subjectively increased difficulties of sleep initiation and sleep termination, as well as by insufficient recuperation. The night shift was characterized by increased subjective difficulties of maintaining sleep, but also by increased ease of sleep initiation. It was concluded that both morning and evening shifts interfered with sleep, although no effects of sleep deprivation were found.

Adult↗
PubMed1989

Relationships between serum triglycerides and gamma-glutamyltransferase among shift and day workers.

Increased levels of serum triglycerides in shift workers have been reported in two population-based studies. In order to examine this relationship and to take some common confounding factors into account this cross-sectional study of 562 shift and day workers was carried out. The shift workers had significantly higher levels of serum triglycerides. gamma-glutamyltransferase and total cholesterol, and Body Mass Index did not differ between the groups. The cause of increased serum concentrations of triglycerides is unclear. The present study provides no evidence to support the assumption that alcohol drinking or obesity accounts for increased levels of serum triglycerides in shift workers.

Adult↗
PubMed1989

Sleep on the night shift: 24-hour EEG monitoring of spontaneous sleep/wake behavior.

The present study sought to objectively describe the spontaneous sleep/wakefulness pattern of shift workers during a 24-hour period. Portable Medilog tape-recorders were used for ambulatory EEG monitoring of 25 male papermill workers (25-55 years) during days with night and afternoon work. The results showed that sleep after night work was two hours shorter than after afternoon work. The sleep reduction affected mainly Stage 2 and REM sleep while slow wave sleep was unchanged. In connection with night work 28% of the workers took a nap in the afternoon. These naps contained a large proportion of slow wave sleep and were, apparently, caused by the sleep deficit after the short main sleep period. The EEG recordings also revealed that 20% of the participants had sleep episodes during night work. These naps were as long as the afternoon naps, were experienced as "dozing offs" rather than naps, occurred at the time of the trough of the circadian wakefulness rhythm, and were concomitant with extreme subjective sleepiness and low rated work load. It was concluded that not only the sleep of shift workers was disturbed, but also the wakefulness--to the extent that sleepiness during night work sometimes reached a level where reasonable wakefulness could not be maintained. The latter observation is probably of special importance in work situations demanding a great responsibility for human lives or for great economic values.

Adult↗
PubMed1989

Shift work and coronary heart disease.

Previous research on the medical consequences of shift work has mainly been concerned with sleep disorders and gastrointestinal disturbances. Cardiovascular disease has not been clearly implicated. The objective of the present study was to investigate a possible association between shift work and Coronary Heart Disease (CHD), which is the most common cause of death in industrialized countries. Previous research is reviewed and criticized for using simple approaches with little ability to quantify exposure and to control for selection. Two longitudinal and two cross-sectional studies have been carried out. One study has measured incidence of CHD in 504 male day and shiftworkers from 1968 to 1982/83. The results indicate that shift work is associated with CHD. Our result has demonstrated a dose-response relationship between years of shift work and CHD. Our findings on increased risk of CHD in shift workers are consistent with recent epidemiological studies from Sweden which have used register data. The cross-sectional studies in which two different cohorts of male blue-collar workers were investigated did show a higher percentage of smokers among shift workers. In addition, the shift workers had higher serum concentrations of serum triglycerides. The difference in serum triglyceride levels between day and shift workers could not be explained by obesity, smoking or alcohol intake in the statistical analyses. These results suggest that the prevalence of risk factors for CHD is higher among shift workers. A prospective study of 25 male shift and day workers, who were followed for six months, indicated that the diet of shift workers might be responsible for changes in the ratio between apoB and apoA-1, a ratio which is related to risk of coronary disease. The analyses of spontaneous changes in the diet showed that the shift workers tended to decrease the intake of dietary fibre and increase the intake of sacharose. The change in the ratio between apoB and apoA-1 correlated inversely with the change in intake of dietary fibre. It is concluded that spontaneous changes in the diet of shift workers might be responsible for changes in serum lipoproteins. Three major disease pathways from shift work to CHD are proposed: (i) disturbed physiological rhythm and/or a collision between the circadian rhythm and myocardial performance, (ii) changes in behaviour, and (iii) disturbed sociotemporal rhythmicity, which might lead to distress reactions.

Adult↗
PubMed1988

Studies of the luteinization process in the rat: development of catecholamine response on progesterone production during the peri-ovulatory period.

The present study was undertaken to investigate whether pre-ovulatory follicles have an adrenergic response in terms of progesterone production. Extirpated pre-ovulatory follicles obtained both before and after the endogenous gonadotropin surge and newly formed corpora lutea were obtained from the PMSG rat ovulatory model. Follicles and corpora lutea were incubated for 120 min in MEM with Earle's salt and 10 mM Hepes, 37 degrees C, pH 7.4 and 100% oxygen, with 30 microM noradrenaline or 10 micrograms ml-1 LH-B9). Pre-ovulatory follicles were barely stimulable by noradrenaline, while newly formed corpora lutea responded markedly. Luteinizing hormone (LH) levels significantly increased progesterone accumulation in all groups. In order to determine whether preovulatory follicles need intact surrounding tissue for an adrenergic response on progesterone production, pieces of ovaries containing pre-ovulatory follicles were incubated. No significant effect of noradrenaline or adrenaline was seen, while LH had a substantial effect. The results show that catecholamines acutely exert a selective effect on steroidogenesis in the ovary with a marked stimulatory effect on corpora lutea and a marginal effect on the pre-ovulatory follicle.

Animals↗
PubMed1988

Prevalence of risk factors for coronary artery disease among day and shift workers.

Several recent studies have indicated that shift work is associated with increased risk of coronary artery disease. In this cross-sectional study 361 shift workers were examined with respect to some major risk factors for coronary artery disease; 240 day workers constituted the reference group. A higher proportion of shift workers smoked (54 versus 39%). Shift workers also had significantly higher levels of serum triglycerides (1.61 versus 1.43 mmol/l). Body mass index and the blood pressure and total cholesterol levels did not differ between the groups. Multiple regression analyses demonstrated that shift work was significantly related to serum triglyceride levels also when age, smoking, body mass index, and other variables were controlled for. It was concluded that shift work is associated with several risk factors for coronary artery disease.

Adult↗
PubMed1986

Increased risk of ischaemic heart disease in shift workers.

504 papermill workers were followed up for 15 years and the incidence of ischaemic heart disease (IHD) in shift workers was compared with that in day workers. The relative risk (RR) of IHD rose with increasing duration of reported exposure to shift work. A significant risk of IHD was associated with an exposure of 11 - 15 years (RR = 2.2, p less than 0.04) and of 16 to 20 years (RR = 2.8, p less than 0.03. The association was independent of age and smoking history. The RR of IHD fell sharply after 20 years of shift work. This was ascribed to the pronounced positive selection that had taken place in this group.

Adult↗
PubMed1986

Computerization in industry causes problems for people with reading and writing difficulties (dyslexia).

For 10 years computerization in industry has advanced at a rapid pace. A problem which has not received attention is that of people with reading and writing difficulties who experience severe problems when they have to communicate with a computer monitor screen. These individuals are often embarrassed by their difficulties and conceal them from their fellow workers. A number of case studies are described which show the form the problems can take. In one case, an employee was compelled to move from department to department as each was computerized in turn. Computers transform a large number of manual tasks in industry into jobs which call for reading and writing skills. Better education at elementary school and at the workplace in connection with computerization are the most important means of overcoming this problem. Moreover, computer programs could be written in a more human way.

Adult↗
PubMed1984

Shift work and cardiovascular disease.

This paper reviews a number of studies which have presented results on the association between shift work and cardiovascular disease. It is suggested that many of the early studies suffer from methodological flaws which render them difficult to interpret. In studies in which incidence of disease has been computed and related to exposure to shift work, the results indicate a higher risk for cardiovascular disease among shift workers as compared to day workers. The evidence cannot yet, however, be considered conclusive.

Cardiovascular Diseases↗
PubMed1975

Immunoglobulins in workers with traumatic vasospastic disease.

Twenty-seven rockdrillers of whom 63% had symptoms of Traumatic Vasospastic Disease were examined. The concentrations of IgG, IgA and IgM in serum were determined with immunoelectrophoresis. The immunoglobulins were found not to be significantly raised.

Adult↗