2010 BC Guide in Determining Fitness to Drive

Chapter 28: Sleep DisordersBACKGROUND28.1 About sleep disordersSleep disorders involve any difficulties related to sleeping, including: difficulty falling asleep (insomnia) or staying asleep falling asleep at inappropriate times excessive total sleep time, or abnormal behaviours associated with sleep.This chapter focuses on the most common form of sleep disordered breathing - obstructive sleepapnea - and on narcolepsy.In addition to sleep disorders, a number of other factors such as work schedules or lifestylechoices may result in inadequate nocturnal sleep. Regardless of the cause, the risks of excessivesleepiness for driving safety are similar.Sleep disordered breathingSleep disordered breathing consists of three distinct clinical syndromes: obstructive sleep apnea-hypopnea syndrome (OSAHS): apnea-hypopnea caused by repeatedclosure of the throat or upper airway during sleep. This is the most common form of sleepdisordered breathing. central sleep apnea-hypopnea syndrome (CSAHS): includes types of apnea-hypopnea causedby a neurological problem that interferes with the brain’s ability to control breathing duringsleep, as well as high altitude periodic breathing, and apnea-hypopnea due to drug orsubstance abuse. sleep hypoventilation syndrome (SHVS): a type of sleep disordered breathing characterizedby insufficient oxygen absorption during sleep. It usually occurs in association withrestrictive lung disease in morbidly obese individuals, with respiratory muscle weakness, orwith obstructive lung disease such as COPD.Obstructive sleep apnea-hypopnea syndromeWith OSAHS, the tissue and muscles of the upper airway repetitively collapse during sleep,reducing or preventing breathing. As oxygen levels in the blood fall, arousal causes the airwayto re-open. Although individuals with OSAHS often remain asleep, their sleep patterns aredisrupted. These sleep disturbances result in excessive daytime sleepiness. Impairments incognitive function are common in individuals with OSAHS and these may include difficulties in: attention concentration341