Daytime sleepiness fall asleep and driving performance Bttner 2001 2009

The ability to drive safely and without accident needs sustained attention and alertness (Guilleminault et al. 1978, Bradley et al. 1985, Podszus et al. 1986, Findley et al. 1988a/b, 1989b, 1990, 1991, 1995, He et al. 1988, Mitler et al. 1988, Lamphere et al. 1989, Roehrs et al. 1989, Bedard et al. 1991, Cassel et al. 1991a/b, 1993, 1996, Kribbs et al. 1993a/b, ATS 1994, Martin et al. 1996, Gerdesmeyer et al. 1997, Krieger et al. 1997, Randerath et al. 1997, 1998, Weeß 1997, Weeß et al. 1998a/b).

Increased daytime sleepiness is one of the most common causes of road accidents. Driver fatigue is the cause in up to 25% of highway accidents (Langlois et al. 1985, Pack et al. 1994, Horne et al. 1995). A study of 67 671 non-alcohol-related car accidents in France in the years 1994-1998 showed that the risk of accidents involving fatalities or serious injuries in fatigue-related accidents is increased as compared to non-fatigue-related accidents significantly (Philip 2000). An analysis of fatal accidents on highways in Bavaria in 1991 showed that 49 of 204 accidents (24%) caused by falling asleep at the wheel (Langwieder et al. 1994). Obstructive Sleep Apnea Syndrome is again one of the most common causes of daytime sleepiness is increased (American Thoracic Society 1994, McNicholas, 1999). Reliable data on sleepiness-related causes of accidents due to the German data protection regulations is not available and caused on it the published data's are very inconsistent: According to Seko et al. (1986) 45% of all fatal road accidents were caused by falling asleep at the wheel or a micro-sleep, but declared by the Federal Statistical Office at Wiesbaden (1988) only 0.5% of all traffic accidents (Seko et al. 1986, Federal Statistical Office Wiesbaden 1988, Cassel et al. 1993). A study of Zulley et al. showed that 38% in all traffic accidents on Bavarian highways were due vigilance reduction and 24% of all serious accidents (Zulley et al. 1995). The sleep-related vigilance and sustained attention losses were intensified, especially exacerbated by the effects of biological rhythms (Hildebrandt et al. 1974, Hildebrandt 1976, Mitler 1991, Cassel et al. 1991c, 1993, Zulley 1995).

As early as 1955 Prokop and Prokop discussed regarding traffic safety and the importance of fatigue and falling asleep, but without to discuss the sleep-related aspects or causes (Prokop & Prokop 1955, Cassel et al. 1993). At first in 1978 Guilleminault et al. showed a possible increased risk for patients with sleep-disordered breathing (Guilleminault et al. 1978, Cassel et al. 1991a/b).

George et al. (1987) took up this assumption and investigated the accident probability of 27 suspected OSAS patients. In 93% of patients were entered injuries in the accident register of Motor Vehicle Branch of Manitoba (Canada), but only 54% of the control group participants. Unfortunately, in seven patients, the polysomnographic confirmation of the diagnosis and the information on the period of specified accidents are missing (George et al. 1987, Cassel et al. 1991a/b, Weefi 1997, Weefi et al. 1998 a/b). Findley et al. (1988b) found that 29 OSAS patients (AHI> 5) a three-fold increased probability of accidents compared to all license holders of Virginia (USA), and even a seven-fold increased compared to a control group (n = 35). However, Findley et al. didn't give the information whether the OSAS diagnosis was already known in the survey (Findley et al. 1988b, Cassel et al. 1991a/b, Weefi 1997, Weefi et al. 1998 a/b). Later studies and studies by Cassel et al. (1991a/b, 1996), the ATS (1994) and Krieger et al. (1997) confirmed these findings. Thus, patients with Sleep Apnea Syndrome seem increasingly to suffer from severe fatigue and falling asleep while driving (see also George et al. 1987, 1996b, Findley et al. 1988b). With increasing impairment of those affected persons by the symptoms of Obstructive Sleep Apnea are also accumulated self-inflicted, sustained attention-related injuries (Cassel et al. 1991a/b, 1996, ATS 1994, Kruger et al. 1997). According to Young et al. (1997), the relative risk of an accident within five years, causing increased for men with sleep-related breathing disorders by factor of 3. Several studies show a minimum of a 2-fold to 3-fold, up to 7-fold increased risk of accidents (George et al. 1987, 1999, Findley et al. 1988, 2000, Horne & Reyner 1995, Wu & Yan-Go 1996, Young et al. 1997, Barbé et al. 1998, Terán-Santos et al. 1999, Horstmann et al. 2000, LLoberes et al. 2000, Sharma & Sharma 2008). For example, George et al. (1999) investigated the relationship between accident rates and the number of traffic offenses in OSAS patients, with the result that the frequency of accidents and the number of traffic violations during a period of five years was significantly higher compared to a control group.

A special group in this context represent professional drivers, bus and truck drivers, because they spend a lot of professional time on the road and also with some larger vehicles usually dangerous cargo or other people, so that probably occur in an accident caused considerable damage and injury. These people have to suffer through their work and the associated lifestyle at increased risk of interference with OSAS. Thus for example truck drivers have a very irregular sleep-wake rhythm (Stradling 1989, Stoohs et al. 1995). In 1994 Stoohs et al. researched the influence of sleep-disordered breathing (SDB) and obesity among commercial drivers of large trucks. Drivers with SDB cause twice as many accidents per 1000 driven miles, than that without SDB, and obesity, the accident rate still increased. Accidents caused by overtiredness-related un-roadworthy and related offenses are likely among professional drivers having accepted a level that is comparable to the drunken crime (Meyer 1990). The diagnosis of central nervous system stimulation as well as the diagnosis of daytime sleepiness has therefore central importance in the sleep medical field. Thus, the daytime sleepiness is on the one hand understood as an important symptom of non-restorative sleep, but on the other hand can also be closed due to their expression on the severity of this sleep disorder. Ultimately, their diagnostic evaluation is also an important criterion for therapy evaluation.

The sleepiness-related medical history or diagnosis is used to assess the clinical and social impact of daytime sleepiness. In particular, the severity and the social and medical risk will be assessed. It can also be used as parameters of the differential diagnosis of fatigue. This anamnesis can be supported by the use of orienting processes or by the method of screening.

It is used especially in the assessment of type and of frequency about the tendency to fall asleep, micro-sleep episodes and monotony intolerance at work (especially in monitoring activities) and to capture the possibility of active participation in road traffic and other social situations (Walsleben 1992, Weefi 2011).

The Epworth Sleepiness Scale (ESS), the Stanford Sleepiness Scale (SSS), the Multiple Sleep Latency Test (MSLT) and the Maintenance Wakefulness Test (MWT) are among the methods that are most widely used for the investigation of daytime sleepiness in sleep disorders. The ESS reflects the global and subjective severity of daytime sleepiness in eight different situations and activities of daily living. The SSS is, however, to capture subjective circadian fluctuations of daytime sleepiness. To objective capture electrophysiological and standardized tests are often, such as the MSLT and the MWT used to determine the degree of alertness on the basis of tonic activation.

If, on the basis of questionnaire data and medical history of sleeping on the basis of suspicion that a pathological daytime sleepiness (Table 1) exists, then objective analysis methods can be used to measure sleepiness-related functions.

Central nervous system activation Vigilance Selected Attention Divided Attention Table 1. Sleepiness functions

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