Perception versus Reality: The Relationship between Subjective and Objective Measures of Sleep When On-call under Simulated Laboratory Conditions

BACKGROUND

On-call working arrangements have been shown to negatively impact sleep. However, workers may perceive their sleep to be worse than it actually is. The aim of this study was to compare participants' pre- and post-sleep estimates of sleep duration and sleep quality with objectively measured sleep when on-call under laboratory conditions.

PARTICIPANTS

72 healthy, adult males.

METHODS

Analyses were performed on three interrelated studies, all of which consisted of four nights in a sleep laboratory. Following adaptation and baseline nights were two on-call nights (sleep opportunity 23:00 h - 07:00 h). Before and after each sleep opportunity, participants provided subjective estimates of sleep. Sleep was objectively measured using polysomnography.

RESULTS

Estimated sleep duration (6.74 ± 1.13 h) and sleep onset latency (20.55 ± 14.85 min) were significantly poorer than objectively measured sleep outcomes (sleep duration 7.21 ± 1.25 h; sleep latency 13.20 ± 10.06 min). Of the variance in post-sleep estimated sleep duration, 14% was associated with objectively measured minutes of N3 (R²Δ = 0.55) and REM (R²Δ = 0.75). Additionally, 14% of post-sleep sleep quality estimation variance was associated with minutes of N2 (R²Δ = 0.60) and N3 (R²Δ = 0.79), measured by polysomnography.

CONCLUSIONS

Some objective measures of sleep were associated with subjective estimates of sleep duration and sleep quality. However, individuals may overestimate sleep onset latency and underestimate sleep duration during on-call periods. It may be beneficial for on-call workers to actively reflect on feelings of fatigue/alertness for workplace fatigue management, rather than relying solely on estimates of sleep.

Population-based analysis of sociodemographic predictors, health-related quality of life and health service use associated with obstructive sleep apnoea and insomnia in Australia

Although there is growing recognition of the effects of living with sleep disorders and the important role of primary care in their identification and management, studies indicate that the detection of sleep apnoea (OSA) and insomnia may still be low. This large representative community-based study (n=2977 adults) used logistic regression models to examine predictors of self-reported OSA and current insomnia and linear regression models to examine the association of these sleep conditions with both mental and physical components of health-related quality of life (HRQoL) and health service use. Overall, 5.6% (95% confidence interval (CI) 4.6-6.7) and 6.8% (95% CI 5.7-7.9) of subjects self-reported OSA (using a single-item question) and current insomnia (using two single-item questions) respectively. Many sociodemographic and lifestyle predictors for OSA and insomnia acted in different directions or showed different magnitudes of association. Both disorders had a similar adverse relationship with physical HRQoL, whereas mental HRQoL was more impaired among those with insomnia. Frequent consultations with a doctor were associated with a lower physical HRQoL across these sleep conditions; however, lower mental HRQoL among those frequently visiting a doctor was observed only among individuals with insomnia. The adverse relationship between sleep disorders and physical and mental HRQoL was substantial and should not be underestimated.

0722 The Association Between Obstructive Sleep Apnea and Neurobehavioural Function in Men: A Large, Population-Based Cohort Study

Introduction

Obstructive sleep apnea (OSA) is linked with impaired vigilance, attention, memory and executive function. However, this evidence largely comes from small experimental studies or larger studies in clinical samples and therefore the scope and magnitude of OSA driven neurobehavioural dysfunction in the general population remains unclear. This study aimed to examine the cross-sectional association between OSA and neurobehavioural function in a large community sample of men.

Methods

A total of 837 participants from the Men Androgen Inflammation Lifestyle Environment and Stress (MAILES) study, a longitudinal cohort of men 40+ years, underwent full overnight polysomnography. Participants completed the inspection time (IT) test, mini-mental state examination (MMSE), Fuld object memory evaluation (FOME), and trail-making test (TMT) part A (TMT-A) and part B (TMT-B). Using regression models adjusted for multiple important covariates, we examined the association between neurobehavioural function scores, clinical metrics of OSA severity (Apnea-Hypopnea Index (AHI); percentage total sleep time with oxygen saturation <90% (TST90), and measures of sleep disruption (duration of rapid eye movement (REM) and non-REM (NREM) sleep; and total sleep time (TST).

Results

In multivariable linear regressions, greater TST was associated with worse IT scores (B=13.688, 95% CI [0.134, 27.241], P=0.048) and TMT-B scores (B=19.255, 95% CI [0.931, 37.578], P=0.040). In logistic regressions, greater TST was associated with better MMSE scores (Odds ratio [OR]=0.440, 95% CI [0.194, 0.997], P=0.049); and higher AHI was strongly associated with worse FOME scores in fully adjusted models (OR=1.358, 95% CI [1.252, 1.472], P<0.001).

Conclusion

The AHI and TST were positively, significantly associated with neurobehavioural function across different domains. This cross-sectional data shows that neurobehavioural function deficits in OSA are directly related to sleep and breathing disruptions. Future large prospective studies are needed to determine if OSA and sleep disruption predict future onset of neurobehavioural dysfunction and cognitive decline.

Support

National Health and Medical Research Council and the Adelaide Institute for Sleep Health.

Sleep Disorders, Including Sleep Apnea and Hypertension

There is mounting evidence for an association between sleep disorders and hypertension. In obstructive sleep apnea (OSA), there are plausible biological reasons for the development of hypertension, and treatment of OSA results in modest (2-3 mm Hg), adherence-dependent decreases in blood pressure, with larger effects evident in those with resistant hypertension. However, prospective, population-based cohort studies have not yet convincingly demonstrated a link between OSA and incident hypertension, and adequately powered controlled trials of CPAP for the prevention or treatment or hypertension are lacking. While associations have been identified between short sleep duration, insomnia, restless legs syndrome (RLS), shift work, and hypertension, the causative role of these conditions/circumstances is not proven, and further well-designed pathophysiological and/or interventional studies are needed. Particular emphasis should be placed on defining subgroups of hypertensive OSA patients that stand to benefit most from OSA treatment and in understanding the link between sleep apnea and hypertensive disorders of pregnancy. Well-controlled intervention studies are needed in populations with short sleep duration, insomnia, shift work sleep disorder, and RLS to confirm their putative links with hypertension.

Effects of moderate sleep deprivation and low-dose alcohol on driving simulator performance and perception in young men

STUDY OBJECTIVE

To determine the combined effects of sleep restriction and low-dose alcohol on driving simulator performance, EEG, and subjective levels of sleepiness and performance in the mid-afternoon.

DESIGN

Repeated measures with 4 experimental conditions. Normal sleep without alcohol, sleep restriction alone (4 hours) and sleep restriction in combination with 2 different low blood alcohol concentrations (0.025 g/dL and 0.035 g/dL).

SETTING

Sleep Laboratory, Adelaide Institute for Sleep Health.

PARTICIPANTS

Twenty-one healthy young men, aged 18-30 years, mean (+/-SD) = 22.5(+/-3.7) years, BMI = 25(+/-6.7) kg/m2; all had normal sleep patterns and were free of sleep disorders.

MEASUREMENTS

Participants completed a 70-minute simulated driving session, commencing at 14:00. Driving parameters included steering deviation, braking reaction time, and number of collisions. Alpha and theta EEG activity and subjective driving performance and sleepiness were also measured throughout the driving task.

RESULTS

All measures were significantly affected by time. Steering deviation increased significantly when sleep restriction was combined with the higher dose alcohol. This combination also resulted in a significant increase in alpha/theta EEG activity throughout the drive, as well as greater subjective sleepiness and negative driving performance ratings compared to control or sleep restriction alone.

DISCUSSION

These data indicate that combining low-dose alcohol with moderate sleep restriction results in significant decrements to subjective alertness and performance as well as to some driving performance and EEG parameters. This highlights the potential risks of driving after consumption of low and legal doses of alcohol when also sleep restricted.