Elderly Sleep and Stress Introduction the Stress of Caring for a Loved One with Al- Zheimer Disease (ad) Has Been Well Document- Ed in the Literature.1,2 Stresses

THE STRESS OF CARING FOR A LOVED ONE WITH ALZHEIMER DISEASE (AD) HAS BEEN WELL DOCUMENTED IN THE LITERATURE.1,2 STRESSES ASSOCIATED with caregiving, such as care-recipient problem behaviors, a mismatch between demands and resources (i.e., overload), and affective disturbance may promote sympathoadrenal medullary (SAM) activation. Indeed, research suggests that caregivers have an elevated basal concentration of plasma catecholamines, as compared with noncaregivers,3 and increased depressive symptoms in caregivers appear to exaggerate the norepinephrine response to psychological stress.4 The stress of caregiving also raises the risk of premature mortality. In a study comparing caregivers of people with and without dementia, Schulz and colleagues found an elevated risk for mortality among those caregivers reporting high levels of strain.5 Indeed, other research suggests that caregivers of people with dementia report greater strain than do caregivers of people without dementia.6 This elevated mortality risk may be due in part to the effects of caregiving stress on the cardiovascular system.7,8 Although affective disturbance and caregiving stress appear to be related to SAM arousal, other factors associated with stress, such as sleep disturbance, may provide an alternate explanation for these relationships. Poor sleep is common among caregivers9 and has been associated with increased risk for heart disease.10 Wilcox and King11 examined sleep in 90 caregivers of patients with AD and found that caregivers reported more sleep complaints than did age-matched, healthy people who were not caregivers. In that study, the most common complaint was being awakened during the night, with more than half of the caregivers reporting nighttime disruptions caused by the care recipient. In another study, Happe and Berger12 found that 27% of caregivers of people with Parkinson disease experienced frequent sleep disturbances and that sleep disturbance was proportionate to the level of caregiving stress. Sleep disturbance, and in particular obstructive sleep apnea (OSA), has been linked with a number of biologic outcomes related to cardiovascular disease.13-16 In a review of the relationship between sleep fragmentation and biologic outcomes, Shamsuzzamen et al14 concluded that sleep fragmentation plays a role in the initiation and progression of cardiac and vascular disease. OSA, which results in sleep fragmentation, has also been associated with endothelial dysfunction, increased circulating C-reactive protein, interleukin-6, fibrinogen, and reduced fibrinolytic activity,16-18 as well as an increase in plasma and urinary norepinephrine.19-21 The latter findings strongly suggest that OSA confers a hypercoagulaSleep Disturbance, Norepinephrine, and D-Dimer Are All Related in Elderly Caregivers of People With Alzheimer Disease