June J. Pilcher

Sleep quality versus sleep quantity: Relationships between sleep and measures of health, well-being and sleepiness in college students

Two studies assessed whether measures of health, well-being, and sleepiness are better related to sleep quality or sleep quantity. In both studies, subjects completed a 7-day sleep log followed by a battery of surveys pertaining to health, well-being, and sleepiness. In subjects sleeping an average of 7 hours a night, average sleep quality was better related to health, affect balance, satisfaction with life, and feelings of tension, depression, anger, fatigue, and confusion than average sleep quantity. In addition, average sleep quality was better related to sleepiness than sleep quantity. These results indicate that health care professionals should focus on sleep quality in addition to sleep quantity in their efforts to understand the role of sleep in daily life.

Effects of hot and cold temperature exposure on performance: a meta-analytic review.

A meta-analysis to mathematically summarize the effect of hot and cold temperature exposure on performance was completed. The results from 515 effect sizes calculated from 22 original studies suggest that hot and cold temperatures negatively impact performance on a wide range of cognitive-related tasks. More specifically, hot temperatures of 90°F (32.22°C) Web Bulb Globe Temperature Index or above and cold temperatures of 50°F (10°C) or less resulted in the greatest decrement in performance in comparison to neutral temperature conditions (14.88% decrement and 13.91% decrement, respectively). Furthermore, the duration of exposure to the experimental temperature, the duration of exposure to the experimental temperature prior to the task onset, the type of task and the duration of the task had differential effects on performance. The current results indicate that hot and cold temperature exposure have a negative impact on performance and that other variables (e.g., length of exposure to the temperature or task duration) may modify this relationship.

The Relationships Between Sleep and Measures of Health and Weil-Being in College Students: A Repeated Measures Approach

The stability of subjective measures of sleep, health, and well-being, as well as the stability of the relationships between sleep and health and well-being were assessed over 3 months. Healthy college students with no consistent sleep complaints completed a 7-day sleep log and battery of surveys related to health and well-being at 3 separate times during the 3 months. Measures of health and well-being were more strongly related to the quality than to the quantity of sleep. Further analyses using the repeated measures results found that participants reported improved sleep and better health, but the affect balance, life satisfaction, and mood states were unchanged across the 3 testing periods. The relationships between the measures of sleep and measures of health and well-being remained constant across the experimental period. Even when working with a non-sleep-disturbed population, healthcare professionals should consider sleep quality as a consistent correlate of daily health and well-being.

Affective and Daily Event Predictors of Life Satisfaction in College Students

The current study examined how well affect and daily events predict life satisfaction in 72 college students. Surveys assessing mood, affect balance, health, and sleep quality provided estimates of affect and daily events. The Satisfaction with Life Scale (SWLS) was used as a measure of general life satisfaction. The current results indicated that the SWLS was significantly correlated with feelings of depression, anger, vigor, and confusion, with physical health and frequency of physical illness, with positive and negative affect, and with sleep quality. The predictor variables used in the current study accounted for 54.1% of the total variance of the SWLS. However, only depression, vigor, confusion, frequency of illness and negative affect were significant predictors of life satisfaction in both a standard regression model and in a hierarchical forward regression model. More practically, an increase in subjective life satisfaction was predicted by decreases in depression, decreases in negative affect, decreases in the frequency of illness, and increases in vigor. These results indicate that judgements of life satisfaction, as measured by the SWLS, were significantly predicted by affect and daily events.

Work/rest cycles in railroad operations: effects of shorter than 24-h shift work schedules and on-call schedules on sleep

The current study examined the frequency with which shorter than 24-h work/rest cycles occur in locomotive engineer work schedules, and what effects these work/rest cycles had on sleep quantity and sleep quality. The results indicated that shorter than 24-h work/rest cycles occurred in 33.6% of the work days reported by 198 locomotive engineers. In addition, the shorter than 24-h work/rest cycles occurred more frequently in work schedules that created an on-call work system, such as road pool turn and extra board assignments, than in work schedules that used more predictable or regular work times, such as regular road assignments and yard/local work. As would be expected, when engineers worked shorter than 24-h work/rest cycles, they reported less sleep and poorer sleep than under the longer than 24-h work/rest cycles. Similarly, on-call work assignments resulted in less sleep and poorer sleep than regular work assignments. These results indicate that specific aspects of the work schedules used in railroad operations, particularly on-call operations that result in shorter than 24-h work/rest cycles, can lead to increased sleep-related problems. Although the North American railroad industry is making significant changes in on-call operations to minimize sleep-related problems from on-call schedules, better fatigue-related models validated within the railroad industry are needed.

The Prevalence of Daytime Napping and Its Relationship to Nighttime Sleep

Abstract Many healthy adults report daytime napping. Surprisingly few studies, however, have examined spontaneous napping behavior, especially very short naps, in healthy adults. The authors examined the prevalence of power naps (lasting less than 20 minutes) and longer naps (20 minutes or more) and their effects on nighttime sleep in a group of healthy young and middle-aged adults. The young and middle-aged adults reported very similar sleep and napping patterns, with approximately 74% of the participants in both groups reporting they had napped during a 7-day sleep-log period. Almost half of the participants reported that the average nap lasted less than 20 minutes. A multivariant analysis of variance (MANOVA) found no significant differences between the no-nap and the power-nap or long-nap groups in sleep quantity or quality for either age group. The current data suggested that power napping occurs frequently in healthy adults and that spontaneous napping does not negatively affect nighttime sleep.

The effects of 28 hours of sleep deprivation on respiratory sinus arrhythmia during tasks with low and high controlled attention demands.

Task performance while sleep deprived may be moderated by the controlled attention required by the task (Pilcher, Band, Odle-Dusseau, & Muth, 2007). This study examined the effects of 28 h of sleep deprivation on respiratory sinus arrhythmia (RSA) during tasks with low and high controlled attention demands. The results showed that RSA increased throughout the night for both task types, but was consistently reduced during the low compared to high controlled attention tasks. The increase in RSA was linear for the high controlled attention tasks but curvilinear for the low ones. Hence, RSA followed a circadian pattern during the low controlled attention tasks but not the high ones. These results suggest that the effects of sleep deprivation on task performance may be moderated by parasympathetic activity and task type, and this has implications for task assignment during sustained operations that cause sleep deprivation.

SUBJECTIVE PERCEPTIONS OF THE EFFECTS OF SUSTAINED PERFORMANCE UNDER SLEEP-DEPRIVATION CONDITIONS

In todays society, numerous situations arise in which sleep deprivation is a common occurrence. Subjective perceptions are a vital component to understanding the effects of sustained performance during sleep deprivation, as they may be the first indication of the effects of sustained performance or sleep deprivation on the individual. Using the theoretical framework of the Controlled Attention Model, this study examined the effects of 16 h of sustained performance under 28 h of acute sleep deprivation on perceived effort, motivation, and stress of 24 participants while completing a complex cognitive and a simple vigilance task. Perceived effort increased for both tasks, with higher effort reported on the cognitive than the vigilance task at the beginning of the experimental period, but with higher effort reported on the vigilance than the cognitive task at the end. Subjective motivation decreased for both tasks, with significantly higher levels of motivation on the cognitive than the vigilance task. Perceived stress did not change for either task. Results suggest that functioning under sustained performance and sleep-deprivation conditions affects subjective perceptions differently for cognitive versus vigilance tasks. The controlled attention model offers one means of understanding how different tasks could affect a persons subjective perceptions and ability to perform, in that different levels of controlled attention are required for the two tasks. (Author correspondence: hodle@gettysburg.edu)

Blood Pressure Increases During a Simulated Night Shift in Persons at Risk for Hypertension

BackgroundShift work with sleep disruption is a systemic stressor that may possibly be associated with blood pressure dysregulation and hypertension.PurposeWe hypothesize that rotation to a simulated night shift with sleep deprivation will produce blood pressure elevations in persons at risk for development of hypertension.MethodWe examined the effects of a simulated night shift on resting blood pressure in 51 diurnal young adults without current hypertension. Resting blood pressure was monitored throughout a 24-h period of total sleep deprivation with sustained cognitive work. Twelve participants (23.5%) reported one or more parents with a diagnosis of hypertension. Ten participants were classified as prehypertensive by JNC-7 criteria. Only two prehypertensive subjects reported parental hypertension.ResultsResults indicate that, as the night shift progressed, participants with a positive family history of hypertension showed significantly higher resting diastolic blood pressure than those with a negative family history of hypertension (p = 0.007). Prehypertensive participants showed elevated blood pressure throughout the study.ConclusionThese data suggest that rotation to a simulated night shift with sleep deprivation may contribute to blood pressure dysregulation in persons with a positive family history of hypertension.

Assessing subjective daytime sleepiness: an internal state versus behavior approach.

Abstract The authors purpose in the current study was to apply P. J. Langs (1968, 1971, 1985) theory of multiple systems of emotional response to the study of subjective sleepiness. A total of 274 participants completed the Stanford Sleepiness Scale (SSS), the Profile of Mood States (POMS), three sleepiness-related Visual Analogue Scales (VAS), and the Epworth Sleepiness Scale (ESS). The authors completed correlations and factor analysis of the 4 sleepiness measures. The SSS, POMS, and VAS measures were better correlated with each other than with the ESS. Similarly, the SSS, POMS, and VAS measures loaded highly onto one factor, whereas the ESS loaded highly onto a separate factor. These results indicated that the ESS measured a different aspect of subjective sleepiness than the SSS, POMS, or VAS. According to Langs emotional responses theory, the ESS assessed a behavioral component of sleepiness, and the SSS, POMS, and VAS measures assessed an internal state related to sleepiness.