Biserka Radošević-Vidaček

Personality differences in the phase of circadian rhythms: a comparison of morningness and extraversion

Abstract Individual differences in the phase of circadian (around 24 h) rhythms are thought to be important in determining adjustment to shift work and rapid time-zone transitions. Attempts to predict such phase differences on the basis of paper and pencil ‘personality’ tests have concentrated on extraversion and morningness, of which Kerkhof (1985), in a recent review of this literature, concluded morningness was the more important. However, the literature on which this conclusion was based suffers from a number of problems. The present study attempted to overcome these problems by examining the trends over a complete 24 h cycle for a range of performance and psychophysiological measures in students with extreme scores for both extraversion and morningness. In general, the results support KerkhoFs conclusion. However, reliable phase differences associated with morningness were confined to subjective ratings of alertness, oral temperature, and, in combination with extraversion, choice reaction time. Two a...

Productivity on a weekly rotating shift system: circadian adjustment and sleep deprivation effects?

Abstract There is little doubt that productivity and safety can be impaired on the night shift. Two main factors have been identified that may be responsible for this. On the one hand, the circadian rhythm in performance on at least simple tasks is at a low ebb at night, and adjusts only slowly over a span of night shifts. On the other, the day sleeps of shift workers taken between night shifts are of a reduced duration, and thus a cumulative sleep debt may accrue over successive night shifts. The former thus predicts that productivity should improve over a span of night duty, while the latter predicts that it should decline. We have examined the productivity of 53 female shift workers, and the sleeping habits of a sub-sample of 30 of them, on a weekly rotating shift system in order to assess the relative contribution of these two factors. Our results suggest that circadian adjustment to night work is the dominant factor for the first three or four successive nights shifts, but that sleep deprivation effe...

Sick building syndrome - psychological, somatic and environmental determinants

The authors aimed to examine potential relationships between work-related symptoms attributed to sick building syndrome (SBS) and certain psychological, somatic, and environmental factors. The multidisciplinary, cross-sectional study comprised 171 female subjects working in air-conditioned and naturally ventilated nonindustrial office buildings. The authors collected information concerning symptoms related to SBS and made assessments of quality of life by using appropriate questionnaires. They assessed the womens levels of emotional stability or neuroticism using the Cornell Index. They determined skin and airway reactivity markers and indoor microclimate data by using standardized methods. The study showed that the subjects had a high prevalence of fatigue (60.2%), sore and dry eyes (57.9%), and headache (44.4%), as well as a generally high score according to the SBS Index. Neuroticism and subjectively estimated physical health as well as the type of building ventilation significantly contributed to the prediction of the SBS Index, explaining 15% of the variance.

Individual differences in circadian rhythm parameters and short-term tolerance to shiftwork: a follow-up study

The relationship between individual differences in the phase and amplitude of circadian rhythms and tolerance to shiftwork has been the subject of several studies. Those studies recorded circadian rhythms and shiftwork tolerance at approximately the same time. The present study aimed to examine the predictive relationships between the amplitude, phase, and mesor of 24 h rhythms obtained before exposure to shiftwork, and subsequent indices of tolerance measured after one and three years of shiftwork. The results revealed some stable relations between the various rhythm parameters and subsequent tolerance measures. Workers who had a higher mesor of positive moods, and a lower mesor of negative moods and fatigue, before entering shiftwork tended to tolerate shiftwork better. Further, those whose heart rate rhythm showed an earlier acrophase had better subsequent sleep quality scores, while those with a smaller amplitude of their temperature, negative mood and fatigue rhythms showed better night-shift tolerance.

Morningness–eveningness and sleep patterns of adolescents attending school in two rotating shifts

School system in which classes are scheduled 1 week in the morning and the other in the afternoon, and in which students rotate schedule every week, fosters sleep irregularity. In this study, we examined morningness–eveningness of adolescents who were involved in such schedule of school time and explored relationship between their circadian preferences and sleep characteristics. A large sample of 2287 students between the ages 11 and 18 years (52% girls) from 24 schools in Croatia was studied. The School Sleep Habits Survey was modified to enable differentiation of sleep patterns between the two school schedules and weekends. Two measures of ME were used: the Morningness–Eveningness Scale for Children (MESC) and mid-sleep time on weekends (MSFsc). Both measures showed a shift to eveningness starting between the ages 12 and 13 (MESC), or 13 and 14 (MSFsc). However, MESC demonstrated a plateau in the shift in older adolescent whereas MSFsc indicated further progress of phase delay. Significant differences in sleep timing and duration were found between three chronotype groups (Morning, Intermediate, and Evening). Generally, Evening types went to bed and woke up the latest in all situations. Their sleep duration was the shortest on school week with morning schedule. On weekends Morning types slept shorter than other two chronotype groups. On school week with afternoon schedule all chronotype groups slept close to the recommended 9 h. All three chronotype groups delayed their bedtimes and wake-up times, and extended their sleep in situations with fewer constraints on sleep timing (i.e. afternoon school schedule, and weekends versus morning school schedule). Expectedly, the evening types showed the greatest sleep irregularity. The findings of this study suggest that the Croatian school system fosters sleep irregularity, but provides more opportunity for fulfilling sleep need of all chronotype groups of adolescents. Age effects on morningness–eveningness observed in Croatian adolescent do not seem to be different from those observed in adolescents from other countries involved in a regular morning school schedule. Further studies are necessary to explore differences in the trend of shift towards eveningness found between the two measures of morningness–eveningness in this, as well as in other studies.

Sleep and napping in young shiftworkers : A 5-year follow-up

Abstract The present study examined sleep characteristics in young workers who entered rapidly rotating shiftwork for the first time and stayed on shifts for 5 years. Data were collected when the subjects had shiftwork experience of approximately 1.5, 3.5 and 5.5 years and a mean age of 22, 24 and 26 years. Data are presented showing significant differences in the main sleep durations between situations within the shift cycle and a small reduction in overall sleep over the observed period, primarily due to a sleep reduction on afternoon shift days. Data on sleep quality did not show any change over this early period of shiftwork exposure. In addition, napping strategies did not change, with the exception of a small increase in those taking naps on night-shift days between 1.5 years and 3.5 years of shiftwork exposure. At all the observed phases there were more young shiftworkers taking a nap on the morning shift days than on the night-shift days. The data suggested that reduced sleeps on morning and night...

Is Atopy Related to Neuroticism, Stress, and Subjective Quality of Life?

Is Atopy Related to Neuroticism, Stress, and Subjective Quality of Life? Different psychosocial characteristics have been associated with allergic disorders. The aim of this study was to examine whether atopic constitution and reports of allergic symptoms were related to personality trait of neuroticism, exposure to stressful life events and estimates of quality of life. Atopy was determined by skin prick test and reports of nasal and pulmonary allergy-related symptoms. Actively working individuals of both genders took part in the study (n=145, age range: 20 to 66 years). The participants were divided in three groups. The first group was composed of those with negative skin prick test and without symptoms (n=57), the second of those with positive skin prick test but without symptoms (n=28), and the third of those with positive skin prick test and symptoms (n=60). The groups did not differ significantly in neuroticism, exposure to stressful life events, or quality of life. Women reported more pronounced neuroticism and anxiety, higher exposure to stressful life events, and were less satisfied with their environment than men. In our sample of active workers we found no association of neuroticism, exposure to stressful life events, and quality of life with atopy and allergic symptoms. Je li atopija povezana s neurotizmom, stresom i subjektivnom kvalitetom života? Dosadašnja istraživanja upućuju na međusobnu povezanost psihosocijalnih čimbenika i alergijskih poremećaja. Cilj ovog rada bio je ispitati jesu li atopijska konstitucija i alergijski simptomi povezani s neurotizmom kao osobinom ličnosti, izloženošću stresnim životnim događajima i subjektivnim procjenama kvalitete života. Stanje atopije određeno je s pomoću kožnog prick testa te izvještajima o nosnim i plućnim alergijskim simptomima. U ispitivanju su sudjelovale radno aktivne osobe obaju spolova (n=145) u dobi od 20 do 66 godina. Sudionici su podijeljeni u tri skupine. Jednu skupinu činili su sudionici s negativnim kožnim prick testom, koji nisu imali alergijske simptome (n=57). Drugu skupinu činili su sudionici s pozitivnim kožnim prick testom, ali koji nisu imali alergijske simptome (n=28). Treću skupinu činili su sudionici s pozitivnim kožnim prick testom koji su također imali i alergijske simptome (n=60). Skupine se nisu značajno razlikovale u neurotizmu, izloženosti stresnim životnim događajima i kvaliteti života. Kod žena je, neovisno o skupini, stupanj neurotizma i anksioznosti bio viši, izvještavale su o većoj izloženosti stresnim događajima te procijenile kvalitetu života u domeni okoliša nižom nego muškarci. Rezultati ovog ispitivanja ne upućuju na povezanost neurotizma, izloženosti stresu i kvalitete života s atopijom i alergijskim simptomima u skupini radno aktivnih osoba.

Shiftwork tolerance and circadian rhythms in oral temperature and heart rate

Abstract The study aimed at establishing differences in the circadian rhythm parameters of oral temperature and heart rate between three groups of workers matched by age: tolerant shiftworkers with good sleep quality and few psychosomatic and digestive complaints, intolerant shiftworkers with poor sleep quality and more psychosomatic and digestive complaints, and workers who had never worked in shifts. The study was performed at an oil refinery recreation centre where the subjects were isolated for three days. During that period they lived under constant conditions, i.e. their activities, timing and content of meals, ambient temperature and light were controlled. Hourly measurements of oral temperature and heart rate were performed over a 24-h period. The parameters of the physiological rhythms were estimated by means of the COSINA method. Generally, the differences between the groups were low and not statistically significant. The authors could find no difference in the amplitude and phase position betwe...

Shiftwork tolerance and 24-h variations in moods

Abstract The objective of the study was to identify the differences in 24-h variations in moods between three groups of oil-refinery workers: tolerant shiftworkers, intolerant shiftworkers and workers who had never worked in shifts. Each group comprised 29 workers matched by age. The mood measurements were taken during a 24-h period every 2 h starting from 08:00 h. Results were scored for three scales: positive moods, negative moods and fatigue. The two-factor ANOVA revealed the significant main effect of groups for all three moods indicating differences at the average level of 24-h variations in all moods between workers who differed in the degree of tolerance to shiftwork. The significant main effect of time of day was also found for all moods while the reliable interaction between groups and time of day was observed for negative moods only, indicating a different shape of 24-h variations for non-shiftworkers in comparison to shiftworkers.

Morningness–eveningness and daytime functioning in university students: the mediating role of sleep characteristics

The aim of this study was to explore the mediating role of sleep characteristics in the relationship between morningness–eveningness and three different aspects of daytime functioning: daytime sleepiness, depressive mood and substance use in university students. A multiple mediator model was proposed with sleep debt, poor sleep quality and bedtime delay at weekends as parallel mediators in these relationships. We analysed the data of 1052 university students aged 18–25 years who completed a modified version of the School Sleep Habits Survey, which included questions on sleep and the Composite Scale of Morningness, Sleepiness Scale, Depressive Mood Scale and Substance Use Scale. Students with more pronounced eveningness reported greater daytime sleepiness, greater depressive mood and more frequent substance use, as well as greater sleep debt, poorer sleep quality and greater bedtime delay at weekends. Mediation analyses indicated that morningness–eveningness affected daytime sleepiness and substance use both directly and indirectly through all proposed sleep‐related mediators. However, the effect of morningness–eveningness on depressive mood was entirely indirect and was accounted for more by poor sleep than by sleep debt or bedtime irregularity. In conclusion, there are multiple possible mechanisms through which morningness–eveningness affects daytime functioning in university students, and sleep characteristics are a significant mechanism. Sleep debt, poor sleep quality and bedtime irregularity can, to a significant extent, explain the feeling of daytime sleepiness and greater substance use in students with eveningness preferences. However, more depressed mood in the evening‐orientated students is primarily a consequence of their poor sleep quality.