Insomnia Risks and Costs: Health, Safety, and Quality of Life
Published Online: August 11, 2010
Mark R. Rosekind, PhD; and Kevin B. Gregory, BS
Insomnia is a disorder of inadequate sleep (poor quantity or quality) that can result in impairment of daytime function or in emotional distress.1,2 There are several types of insomnia, which are not mutually exclusive and include difficulty initiating sleep (sleep-onset insomnia), frequent or long nighttime awakenings (sleep-maintenance insomnia), and waking up too early without being able to return to sleep (also sleep-maintenance insomnia).1 The type of insomnia can vary over time in any individual and is classified based on its duration.3 Acute insomnia lasts 1 to 3 nights, short-term insomnia lasts 3 nights to 1 month, and chronic insomnia lasts longer than 1 month.4 Acute insomnia is often caused by emotional or physical discomfort and, if left untreated, may develop into chronic insomnia.5
Insomnia can exist as a primary disorder or as comorbid with another condition.6 Primary insomnia is commonly caused by life changes, including extended periods of stress or emotional upset.5 Comorbid insomnia (sometimes referred to as secondary insomnia) is the most common type of insomnia, afflicting more than 8 of 10 people with insomnia.5,7 The identification and diagnosis of insomnia are challenged by difficulty and ambiguity because of the variation in the ways insomnia can manifest in an individual, the potential overlap and changes in insomnia symptoms, and the possible disruption of sleep due to lifestyle or environmental factors unassociated with insomnia. Also, there is a discrepancy between subjective reporting and objective measuring of sleep, further complicating insomnia diagnosis and assessment. Generally, insomniacs tend to underestimate their ability to sleep.8
Determining the true prevalence of insomnia is further complicated due to patient underreporting and differences in operational definitions.1,9-11 In the United States, general population surveys consistently find that approximately one-third of adults report having sleep problems.12-15 Within this group, sleep-maintenance insomnia is reported more commonly than sleep-onset insomnia, as demonstrated by an international survey in which 73% of patients with insomnia reported problems with sleep maintenance, 61% reported difficulties falling asleep, and 48% reported poor sleep quality.16 In the 2009 Sleep in America Poll conducted by the National Sleep Foundation, 64% of individuals surveyed had complaints of frequent insomnia, with only 15% being formally diagnosed.15 In this poll, insomnia with nighttime awakenings and with waking up feeling unrefreshed characterized the most prevalent symptoms (46% and 45%, respectively).15
Certain populations have a higher likelihood for developing insomnia.7 Risk factors include female sex,17 increasing age,18,19 employment status,20,21 shift work,21 and a family history of insomnia.22,23 Among women, insomnia seems to be more prevalent in the perimenopausal years, and a gradual increase in insomnia is seen in early-to-late perimenopause transition.24,25 Although older age is associated with an increased risk of insomnia, reports of insomnia or trouble sleeping have been found to peak in middle age (range, 45-54 years), to decrease slightly during older age (range, 65-84 years), and to increase again at very old age (>85 years), suggesting that the relationship between insomnia or trouble sleeping and age may not be linear.26 Greater risk of chronic insomnia exists in shift workers, another group at high risk of insomnia, possibly due to the misalignment of their circadian sleep–wake patterns and sleep–wake schedules.21
This review will focus on the health and societal effects of insomnia as they relate to its economic cost burden. This issue is relevant to managed care organizations and healthcare providers because insomnia contributes to increased direct and indirect consumption of healthcare resources. Improvements in diagnosing and treating insomnia can relieve its cost burden by significantly reducing the associated direct and indirect healthcare costs.
SLEEP ARCHITECTURE AND CHANGES OCCURRING IN INSOMNIA
Normal sleep consists of 2 alternating states, non-rapid eye movement (NREM) sleep and rapid eye movement (REM) sleep.27 The NREM-REM cycle, beginning with NREM, generally occurs 3 to 7 times per night and normally lasts 90 to 120 minutes each time.28 The NREM sleep is composed of 4 stages (NREM1 through NREM4). Stage 1 is viewed as shallow or light sleep, having the lowest arousal threshold, and stage 2 is the transition from light sleep to deep sleep as the heart rate slows and body temperature decreases. Stages 3 and 4 are defined by high-voltage slow-wave activity, with stage 4 having a predominance of these wave-forms.29 Such high-voltage slow-wave activity is characteristic of slow-wave sleep (SWS) or deep sleep. These latter deep sleep stages have the highest arousal threshold and are believed to be required for physical restoration, while REM sleep is required for cognitive restoration.30,31
There are several determinants of a good night’s sleep, and these can be measured in different ways. Sleep efficiency is the ratio of time spent asleep (total sleep time) to the time spent in bed. A decrease in sleep efficiency typically reflects a decrease in total sleep time, which subsequently affects next-day alertness and performance.8 Sleep quality refers to the restorative and undisturbed quality of sleep. The depth of NREM sleep, the amount of REM sleep, and sleep continuity are major determinants of sleep quality.8 Refreshing sleep (ie, sleep that makes one feel refreshed the next day) requires sufficient total sleep time and sleep that is in synchrony with the sleep-wake circadian rhythm.32 Ultimately, good sleep manifests as an ability to function well the next day.
The sleep pattern of individuals with chronic insomnia demonstrates a marked deficiency in the SWS stage.33,34 Electroencephalographic data show that insomniacs have fewer waves that are characteristic of deep sleep and more higher-frequency lower-amplitude waves that are typical of wakefulness, REM sleep, and NREM1 and NREM2 light sleep.29,31,35
EFFECT OF INSOMNIA ON HEALTH, SAFETY, AND QUALITY OF LIFE
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