Data regarding vehicle accidents per hour of the day were supplied by the Italian National Institute of Statistics (ISTAT) and by the Italian Automobile Club (ACI).Data regarding traffic density in the corresponding time span were supplied by the Italian Highways Society. 5 Analysis of Sleep Ascribed AccidentsThe criteria used by police officers to ascribe a given accident to sleepiness are the following:• Suspicion of sleepiness as the major cause, stated by the policeman called on the accident scene. It is based on the pres-Study objective: To evaluate the contributing role of sleepiness in Italian highway vehicle accidents during the time span 1993-1997. Design: We analyzed separately the hourly distribution of accidents ascribed by police officers univocally to sleepiness and the rest. Patients: N/A Interventions: N/A Measurements: Using a polynomial regression, we evaluated the relation between accidents (whether sleep-ascribed or not) and sleepiness as derived from a 24-hour sleep propensity curve. The relation between sleep-influenced and non-sleep influenced accidents was analysed using a linear regression Results: The rate of non-sleep ascribed accidents is closely related with sleep propensity and bears a strong similarity with the pattern of sleepascribed accidents. A close relationship between the curves of non-sleep ascribed accidents and sleep-ascribed accidents is confirmed.The regression coefficient, which can be seen as the ratio between the quota of accidents that can be considered as sleep affected and those actually ascribed to sleepiness, results in a value of 5.83. Considering that the rate of sleep ascribed accidents is 3.2%, we can calculate the quota of sleep influenced accidents out of those not officially ascribed to sleepiness as 18.7% reaching an estimate of accidents related in some way to sleepiness equal to 21.9%. Conclusions: Our indirect estimate of sleep influenced accidents approaches data reported by other European countries and highlights the importance of sleepiness as a direct and/or contributing factor in vehicle accident rates.

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Knowing how and when the degenerative process starts is important in neurodegenerative diseases. We have addressed this issue in fatal familial insomnia (FFI) measuring the cerebral metabolic rate of glucose (CMRglc) with 2-[18F]fluoro-2-deoxy-D-glucose PET in parallel with detailed clinical, neuropsychological examinations and polysomnography with EEG spectral analyses. Nine asymptomatic carriers of the D178N mutation, 10 non-carriers belonging to the same family, and 19 age-matched controls were studied over several years. The CMRglc as well as clinical and electrophysiological examinations were normal in all cases at the beginning of the study. Four of the mutation carriers developed typical FFI during the study but CMRglc and the clinical and electrophysiological examinations remained normal 63, 56, 32 and 21 months, respectively before disease onset. The carrier whose tests were normal 32 months before disease onset was re-examined 13 months before the onset. At that time, selective hypometabolism was detected in the thalamus while spectral-EEG analysis disclosed an impaired thalamic sleep spindle formation. Following clinical disease onset, CRMglc was reduced in the thalamus in all 3 patients examined. Our data indicate that the neurodegenerative process associated with FFI begins in the thalamus between 13 and 21 months before the clinical presentation of the disease.

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