No abstract

Study Objectives: The aim of the study was to investigate how many nights of measurement are needed for a reliable measure of sleep in a working population including adult women and men. Methods: In all, 54 individuals participated in the study. Sleep was assessed for 7 consecutive nights using actigraphy as an objective measure, and the Karolinska sleep diary for a subjective measure of quality. Using intra-class correlation and the Spearman-Brown formula, calculations of how many nights of measurements were required for a reliable measure were performed. Differences in reliability according to whether or not weekend measurements were included were investigated. Further, the correlation between objectively (actigraphy) measured sleep and subjectively measured sleep quality was studied over the different days of the week. Results/Conclusions: The results concerning actigraphy sleep measures suggest that data from at least 2 nights are to be recommended when assessing sleep percent and at least 5 nights when assessing sleep efficiency. For actigraphy-measured total sleep time, more than 7 nights are needed. At least 6 nights of measurements are required for a reliable measure of self-reported sleep. Fewer nights (days) are required if measurements include only week nights. Overall, there was a low correlation between the investigated actigraphy sleep parameters and subjective sleep quality, suggesting that the two methods of measurement capture different dimensions of sleep. I NTRO DUCTI O NThe most common cause for sickness cash benefit in Sweden is psychological ill health.1 The occupational health services (OHS) have a challenging task as special advisers to prevent psychological ill health and stress-related ill health in the work place, providing interventions targeting workplace stress. There is a need for reliable methods to evaluate stress and stress-related health effects in conjunction with these interventions. Measurements of sleep and sleep disturbances may be one option, indicating a (non-beneficial) stress response in a global meaning.Sleep disturbances are often regarded as secondary to-or symptoms of-stress and psychological ill health. Self-rated stress and self-rated sleep are closely related, 2 and sleep disturbances have been shown to be associated with the work stress indicator demand/control/support model 3,4 and to be a mediator in the association between relational justice at work and ill health.5 Sleeping problems have further been shown to be predictors of sickness absence, multisite pain, acute myocardial infarction, and mortality. 6-10 Good or restorative sleep has, on the other hand, been shown to predict the resolution of multisite pain 8 and chronic widespread pain.11 Sleep may thus tell us something about an individual's increased risk of ill health or unfavorable prognosis, and could be a feasible marker of stress globally, when, for example, estimating the health effects of interventions. There are different approaches to measure sleep. One common way to assess how individuals t...

Migraine patients often report intolerance to odours. Migraineurs report odours may trigger attacks, that they experience osmophobia during attacks, and olfactory hypersensitivity between attacks. In this paper we discuss olfactory mechanisms in migraine. We also present data from a pilot questionnaire study in a group of young women diagnosed with migraine. The study results confirm that hypersensitivity to odour is a common feature in women with migraine. Migraine pathophysiology likely explains this particular vulnerability. We discuss these pathophysiologic mechanisms and hypotheses relating odour intolerances and migraine.

Multiple chemical sensitivity (MCS) is characterized by somatic distress upon exposure to odors. As in other idiopathic environmental intolerances, the mechanisms behind the reported hypersensitivity are unknown. Using the advantage of the well-defined trigger (odor), we investigated whether subjects with MCS could have an increased odor-signal response in the odor-processing neuronal circuits. Positron emission tomography (PET) activation studies with several different odorants were carried out in 12 MCS females and 12 female controls. Activation was defined as a significant increase in regional cerebral blood flow (rCBF) during smelling of the respective odorant compared to smelling of odorless air. The study also included online measurements of respiratory frequency and amplitude and heart rate variations by recording of R wave intervals (RR) on the surface electrocardiogram. The MCS subjects activated odor-processing brain regions less than controls, despite the reported, and physiologically indicated (decreased RR interval) distress. In parallel, they showed an odorant-related increase in activation of the anterior cingulate cortex and cuneus-precuneus. Notably, the baseline rCBF was normal. Thus, the abnormal patterns were observed only in response to odor signals. Subjects with MCS process odors differently from controls, however, without signs of neuronal sensitization. One possible explanation for the observed pattern of activation in MCS is a top-down regulation of odor-response via cingulate cortex.

Findings from prior studies of possible health and physiological effects from mobile phone use have been inconsistent. Exposure periods in provocation studies have been rather short and personal characteristics of the participants poorly defined. We studied the effect of radiofrequency field (RF) on self-reported symptoms and detection of fields after a prolonged exposure time and with a well defined study group including subjects reporting symptoms attributed to mobile phone use. The design was a double blind, cross-over provocation study testing a 3-h long GSM handset exposure versus sham. The study group was 71 subjects age 18-45, including 38 subjects reporting headache or vertigo in relation to mobile phone use (symptom group) and 33 non-symptomatic subjects. Symptoms were scored on a 7-point Likert scale before, after 1(1/2) and 2(3/4) h of exposure. Subjects reported their belief of actual exposure status. The results showed that headache was more commonly reported after RF exposure than sham, mainly due to an increase in the non-symptom group. Neither group could detect RF exposure better than by chance. A belief that the RF exposure had been active was associated with skin symptoms. The higher prevalence of headache in the non-symptom group towards the end of RF exposure justifies further investigation of possible physiological correlates. The current study indicates a need to better characterize study participants in mobile phone exposure studies and differences between symptom and non-symptom groups.