Major: Psychology Cardiac patients free from obstructive sleep apnea (OSA) frequently have insomnia symptoms that pose additional risk for future cardiac events. Poor sleep may relate to somatic and psychological hyperarousal that leads to short total sleep time and poor sleep quality. Women who sleep less than or equal to six hours or greater than or equal to nine hours per night are significantly more likely to experience myocardial infarction in the 10 years subsequent to these sleep patterns than women who sleep 7–8 hours per night (Ayas et al., 2003). We hypothesized that implantable cardioverter defibrillator (ICD) patients will have poorer sleep than coronary artery disease (CAD) patients related to hypervigilance for device functioning and worry over shock discharge. No studies to date have used objective measures of sleep to compare sleep patterns among CAD and ICD patients.

We investigated sleep efficiency (a percentage of time spent sleeping divided by time spent in bed) and sleep latency (time between lights out and sleep initiation) in a sample of 60 patients (n = 30 CAD and n = 30 ICD) without OSA at the University of Florida & Shands Hospital. For 14 days, participants completed a daily sleep diary. Additionally, half of the total sample also used actigraphy for 14 days to objectively measure their sleep. An actigraph is watch-like device that infers wakefulness or sleep from the presence or absence of limb movements. Actigraphy strongly correlates with polysomnographic measures of sleep.

Using actigraphy, mean sleep efficiency was poorer (69.76%) in CAD patients and more adaptive (82.80%) in ICD patients. This difference was highly significant, F(1,27) = 16.840, p < .001. CAD patients also had shorter mean total sleep times per sleep diaries (336.19 minutes; 5.60 hours) compared to ICD patients (430.65 minutes; 7.18 hours), F(1,27) = 15.908, p < .001. Ejection fraction% (EF%) and physical activity significantly predicted 56% of the variance in sleep efficiency scores, F(2,26) = 8.322, p = .005.

The finding that ICD patients slept more efficiently than CAD patients is surprising given that CAD patients had higher EF%s. This difference cannot be accounted for by differences in somatic hypervigilance, depression, anxiety, or physical activity levels. Results suggest that chest pain in patients with CAD may be an important consideration in analyzing factors that influence sleep in cardiac patients. Further research is needed to further stratify the exact contribution of both medical and psychological factors in CAD patients.