Quality of life in excessive daytime sleepiness and hypersomnia

Abstract

The ability to be aware of and to interact with the external environment is a basic evolutionary requirement of all higher organisms requiring intact alertness. Hypersomnia and excessive daytime sleepiness (EDS) relate to the inability to maintain an alert state during the major waking periods of the day. Up until recently, somnolence arising due to sleep pathology was misunderstood as a sign of laziness or even malingering by many medical practitioners and society-at-large. The discovery of the orexin/hypocretin receptor system as a key mediator in abnormal daytime sleepiness as well as growing interest in the daytime cognitive impact of common sleep disorders have played important roles in improving scientific and public awareness of hypersomnia as a clinical entity. Hypersomnia, EDS and fatigue are among the most common manifestations of sleep disorders affecting quality of life (QOL) and productivity. In an increasingly interconnected global economy where workload and productivity have shifted towards cognitive as opposed to physical labour, research is now focusing more than ever on the impact of disorders causing somnolence during desired wake time. Similarly, scholastic/academic motivation and performance deficits are being noted in children and adolescents, in part due to the increased 24/7 availability of technology and entertainment options, usually at the expense of sufficient sleep. Other important implications of somnolence include the direct and indirect consequences of transport and occupational accidents, as well as disruption of family and social relationships. Clinical conditions causing this condition include obstructive sleep apnea (OSA), narcolepsy, idiopathic hypersomnia (IH), circadian disturbances and most commonly, self-imposed insufficient sleep syndrome. In conditions such as insomnia, restless legs syndrome (RLS) and periodic limb movements in sleep (PLMS), the association with frank daytime somnolence is more controversial although patients do complain of impaired daytime cognitive function. As the 'baby-boom' generation approaches old age, senescence-related deterioration of sleep quality and quantity is increasingly recognized as an important factor impacting QOL by affecting memory, cognitive function and vitality in activities of daily living (ADLs) including driving. Somnolence can be a serious and even life-threatening impairment. Often there is a gap between the subjective complaints of patients regarding the impact of hypersomnia/EDS on QOL and the ability to reliably measure this dysfunction. An important area of current research involves clarifying the nosology of daytime EDS symptoms, ranging from somnolence to fatigue or neurocognitive impairment. Improvements in diagnostic instruments assessing daytime function and ergonomic activities in relation to both healthy and pathological sleep processes will aid in better delineating these subjective and objective parameters. © 2008 Humana Press, Totowa, NJ.