The Effects of Sleep Time and Sleep Efficiency on Neurobehavioral Outcomes

Purpose and Background: Adequate sleep time and good sleep efficiency are important for optimal health. Shortened sleep times and poor sleep efficiency, such as frequent waking during the night, have been associated with possible detrimental neurobehavioral effects. However, previous studies on this topic have yielded mixed results.

Theoretical Framework: Orem’s Theory of Self-Care guided this clinical study that examined the relationship of participants’ hours of sleep per night and the quality of their time slept with effects on their cognition and behavior.

Method: Using a correlational study design, hours of sleep per night and sleep efficiency scores were analyzed for 80 young adults over 12 weeks of study. Kearney and Fleischer’s Self-Care Agency Scale scores, demographics, and anthropometrics were measured. Sleep times and sleep efficiency scores were determined using sleep actigraphs and the Pittsburgh Sleep Quality Index (PSQI) measured sleep quality. The Sternberg Item Recognition Test measured cognitive memory; and anxiety and depression scores were obtained using Zung’s Self-Rating Anxiety and Depression Scales. Also, lab samples of glucose, serotonin, and cortisol were taken. Correlation and regression analyses were used to determine the effects of time sleeping, sleep efficiency and sleep quality on the participants’ cognitive memory and behavioral affect scores.

Results: The participants’ self-care agency scores were not significantly associated with better cognitive performance. Decreased sleep efficiency was associated with increased irritability (p<.01), depression (p<.01) and higher body mass indices (p<.01). However, the time slept each day was not significantly associated with depression, irritability or cognitive memory scores. Also, the biochemical lab values were not significantly related to the time slept or sleep efficiency or quality ratings. Decreased sleep efficiency (beta=.32; p=.002) and decreased PSQI sleep quality (beta=.38, p<.001) were predictive of increased irritability in the participants. Also, decreased sleep efficiency (beta=-.34; p=.001), decreased PSQI sleep quality (beta=.31; p=.002), and increased BMI’s (beta=-.26; p=.01) were predictive of increased depression in the participants.

Conclusions: Compared with good sleep efficiency scores, poorer sleep efficiency scores had significant associations with increased depression and irritability levels. Given that poorer sleep measures could result in compromised health-related outcomes, a good nights’ sleep seems crucial for optimal health.