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| 3. |
- Ahlström, Christer, et al.
(författare)
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Fit-for-duty test for estimation of drivers sleepiness level: Eye movements improve the sleep/wake predictor
- 2013
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Ingår i: Transportation Research Part C. - : Elsevier. - 0968-090X .- 1879-2359. ; 26, s. 20-32
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Tidskriftsartikel (refereegranskat)abstract
- Driver sleepiness contributes to a considerable proportion of road accidents, and a fit-for-duty test able to measure a drivers sleepiness level might improve traffic safety. The aim of this study was to develop a fit-for-duty test based on eye movement measurements and on the sleep/wake predictor model (SWP, which predicts the sleepiness level) and evaluate the ability to predict severe sleepiness during real road driving. Twenty-four drivers participated in an experimental study which took place partly in the laboratory, where the fit-for-duty data were acquired, and partly on the road, where the drivers sleepiness was assessed. A series of four measurements were conducted over a 24-h period during different stages of sleepiness. Two separate analyses were performed; a variance analysis and a feature selection followed by classification analysis. In the first analysis it was found that the SWP and several eye movement features involving anti-saccades, pro-saccades, smooth pursuit, pupillometry and fixation stability varied significantly with different stages of sleep deprivation. In the second analysis, a feature set was determined based on floating forward selection. The correlation coefficient between a linear combination of the acquired features and subjective sleepiness (Karolinska sleepiness scale, KSS) was found to be R = 0.73 and the correct classification rate of drivers who reached high levels of sleepiness (KSS andgt;= 8) in the subsequent driving session was 82.4% (sensitivity = 80.0%, specificity = 84.2% and AUC = 0.86). Future improvements of a fit-for-duty test should focus on how to account for individual differences and situational/contextual factors in the test, and whether it is possible to maintain high sensitive/specificity with a shorter test that can be used in a real-life environment, e.g. on professional drivers.
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| 4. |
- Anund, Anna, et al.
(författare)
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Observer Rated Sleepiness and Real Road Driving : An Explorative Study
- 2013
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 8:5, s. e64782-
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Tidskriftsartikel (refereegranskat)abstract
- The aim of the present study was to explore if observer rated sleepiness (ORS) is a feasible method for quantification of driver sleepiness in field studies. Two measures of ORS were used:one for behavioural signs based on facial expression, body gestures and body movements labelled B-ORS, andone based on driving performance e.g. if swerving and other indicators of impaired driving occurs, labelled D-ORSA limited number of observers sitting in the back of an experimental vehicle on a motorway about 2 hours repeatedly 3 times per day (before lunch, after lunch, at night) observed 24 participant's sleepiness level with help of the two observer scales. At the same time the participant reported subjective sleepiness (KSS), EOG was recorded (for calculation of blink duration) and several driving measure were taken and synchronized with the reporting.Based on mixed model Anova and correlation analysis the result showed that observer ratings of sleepiness based on drivers' impaired performance and behavioural signs are sensitive to extend the general pattern of time awake, circadian phase and time of driving. The detailed analysis of the subjective sleepiness and ORS showed weak correspondence on an individual level. Only 16% of the changes in KSS were predicted by the observer. The correlation between the observer ratings based on performance (D-ORS) and behavioural signs (B-ORS) are high (r =. 588), and the B-ORS shows a moderately strong association (r =. 360) with blink duration. Both ORS measures show an association (r>0.45) with KSS, whereas the association with driving performance is weak.The results show that the ORS-method detects the expected general variations in sleepy driving in field studies, however, sudden changes in driver sleepiness on a detailed level as 5 minutes is usually not detected; this holds true both when taking into account driving behaviour or driver behavioural signs.
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- Anund, Anna, et al.
(författare)
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Rumble strips in centre of the lane and the effect on sleepy drivers
- 2011
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Ingår i: Industrial Health. - : National Institute of Industrial Health. - 0019-8366 .- 1880-8026. ; 49:5, s. 549-558
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to describe the effects of sleep loss on behavioural and subjective indicators of sleepiness on a road containing a milled rumble strip in the centre of the lane. Particular attention was paid to behavioural and subjective indicators of sleepiness when using the centre lane rumble strip, and to possible erratic driving behaviour when hitting a rumble strip. In total 9 regular shift workers drove during the morning hours after a full night shift and after a full night sleep. The order was balanced. The experiment was conducted in a moving base driving simulator on rural roads with a road width of 6.5 and 9 meters. Out of the 1,636 rumble strip hits that occurred during the study, no indications of erratic driving behaviour associated with the jolt caused by making contact with the centre lane rumble strip could be found. Comparing the alert condition with the sleep deprived condition, both the standard deviation of lateral position (SDLP) and the Karolinska Sleepiness Scale (KSS) increased for sleepy drivers. For the two road widths, the drivers drove closer to the centre line on the 6.5-meter road. The KSS and the SDLP increased with time on task. This simulator study indicates that rumble strips in the centre of the lane may be an alternative to centreline and edgeline rumble strips on narrow roads.
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- Axelsson, John, et al.
(författare)
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Effects of Sustained Sleep Restriction on Mitogen-Stimulated Cytokines, Chemokines and T Helper 1/T Helper 2 Balance in Humans
- 2013
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Ingår i: Plos One. - : Public Library of Science (PLoS). - 1932-6203. ; 8:12
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Tidskriftsartikel (refereegranskat)abstract
- Background: Recent studies suggest that acute sleep deprivation disrupts cellular immune responses by shifting T helper (Th) cell activity towards a Th2 cytokine profile. Since little is known about more long-term effects, we investigated how five days of sleep restriction would affect pro-inflammatory, chemotactic, Th1- and Th2 cytokine secretion. Methods: Nine healthy males participated in an experimental sleep protocol with two baseline sleep-wake cycles (sleep 23.00 - 07.00 h) followed by 5 days with restricted sleep (03.00 - 07.00 h). On the second baseline day and on the fifth day with restricted sleep, samples were drawn every third hour for determination of cytokines/chemokines (tumor necrosis factor alpha (TNF-alpha), interleukin (IL) -1 beta, IL-2, IL-4 and monocyte chemoattractant protein-1 (MCP-1)) after in vitro stimulation of whole blood samples with the mitogen phytohemagglutinin (PHA). Also leukocyte numbers, mononuclear cells and cortisol were analysed. Results: 5-days of sleep restriction affected PHA-induced immune responses in several ways. There was a general decrease of IL-2 production (p<.05). A shift in Th1/Th2 cytokine balance was also evident, as determined by a decrease in IL2/IL4 ratio. No other main effects of restricted sleep were shown. Two significant interactions showed that restricted sleep resulted in increased TNF-alpha and MCP-1 in the late evening and early night hours (p's<.05). In addition, all variables varied across the 24 h day. Conclusions: 5-days of sleep restriction is characterized by a shift towards Th2 activity (i.e. lower 1L-2/IL-4 ratio) which is similar to the effects of acute sleep deprivation and psychological stress. This may have implications for people suffering from conditions characterized by excessive Th2 activity like in allergic disease, such as asthma, for whom restricted sleep could have negative consequences. BAS AK, 1991, IMMUNOLOGICAL REVIEWS, V123, P5
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| 7. |
- Belenky, G, et al.
(författare)
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Occupational Sleep Medicine, introduction
- 2011
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Ingår i: Principle and Practice of Sleep Medicine. - St. Louise : Elisevier Saunders. - 9781416066453 ; , s. 1723-
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Bokkapitel (refereegranskat)
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| 8. |
- Bellavia, Andrea, et al.
(författare)
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Sleep Duration and Survival Percentiles Across Categories of Physical Activity
- 2014
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Ingår i: American Journal of Epidemiology. - : Oxford University Press (OUP). - 0002-9262 .- 1476-6256. ; 179:4, s. 484-491
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Tidskriftsartikel (refereegranskat)abstract
- The association between long sleep duration and death is not fully understood. Long sleep is associated with low physical activity, which is a strong predictor of death. Our aim was to investigate the association between sleep duration and death across categories of total physical activity in a large prospective cohort of Swedish men and women. We followed a population-based cohort of 70,973 participants (37,846 men and 33,127 women), aged 45-83 years, from January 1998 to December 2012. Sleep duration and physical activity levels were assessed through a questionnaire. We evaluated the association of interest in terms of mortality rates by estimating hazard ratios with Cox regression and in terms of survival by evaluating 15th survival percentile differences with Laplace regression. During 15 years of follow-up, we recorded 14,575 deaths (8,436 men and 6,139 women). We observed a significant interaction between sleep duration and physical activity in predicting death (P < 0.001). Long sleep duration (>8 hours) was associated with increased mortality risk (hazard ratio = 1.24; 95% confidence interval: 1.11, 1.39) and shorter survival (15th percentile difference = -20 months; 95% confidence interval: -30, -11) among only those with low physical activity. The association between long sleep duration and death might be partly explained by comorbidity with low physical activity.
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| 9. |
- Bonde, Jens Peter, et al.
(författare)
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Work at night and breast cancer - report on evidence-based options for preventive actions
- 2012
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Ingår i: Scandinavian Journal of Work, Environment and Health. - : Scandinavian Journal of Work, Environment and Health. - 0355-3140 .- 1795-990X. ; 38:4, s. 380-390
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Tidskriftsartikel (refereegranskat)abstract
- In 2007, the International Agency for Research on Cancer classified shift work involving circadian disruption as probably carcinogenic to humans (group 2A), primarily based on experimental and epidemiologic evidence for breast cancer. In order to examine options for evidence-based preventive actions, 16 researchers in basic, epidemiological and applied sciences convened at a workshop in Copenhagen 26-27 October 2011. This paper summarizes the evidence from epidemiological and experimental studies and presents possible recommendations for prevention of the effects of night work on breast cancer. Among those studies that quantified duration of shift work, there were statistically significant elevations in risk only after about 20 years working night shift. It is unclear from these studies whether or not there is a modest but real elevated risk for shorter durations. Hence, restriction of the total number of years working night shift could be one future preventive recommendation for shift workers. The diurnal secretion of melatonin by the pineal gland with peak in secretory activity during the night is a good biochemical marker of the circadian rhythm. Disruption of the diurnal melatonin secretion pattern can be diminished by restricting the number of consecutive night shifts. Reddish light and reduced light intensity during work at night could potentially help diminish the inhibitory activity of light with strong intensity on the melatonin secretion, but further mechanistic insight is needed before definite recommendations can be made. Earlier or more intensive mammography screening among female night shift worker is not recommended because the harm benefit ratio in this age group may not be beneficial. Preventive effects of melatonin supplementation on breast cancer risk have not been clearly documented, but may be a promising avenue if a lack of side effects can be shown even after long-term ingestion. Women with previous or current breast cancer should be advised not to work night shifts because of strong experimental evidence demonstrating accelerated tumor growth by suppression of melatonin secretion. Work during the night is widespread worldwide. To provide additional evidence-based recommendations on prevention of diseases related to night shift work, large studies on the impact of various shift schedules and type of light on circadian rhythms need to be conducted in real work environments.
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