An overview of the report of the national commission on sleep disorders research

The EEG correlates and dangerous behavioral consequences of drowsy driving after a single night of mild sleep deprivation

OBJECTIVE

Here, we investigated the behavioral, cognitive, and electrophysiological impact of mild, acute sleep loss via simultaneously recorded behavioral and electrophysiological measures of vigilance during a "real-world", simulated driving task.

METHODS

Participants (N = 34) visited the lab for two testing days where their brain activity and vigilance were simultaneously recorded during a driving simulator task. The driving task lasted approximately 70 mins and consisted of tailgating the lead car at high speed, which braked randomly, requiring participants to react quickly to avoid crashing. The night before testing, participants either slept from 12am-9am (Normally Rested), or 1am-6am (Sleep Restriction).

RESULTS

After a single night of mild sleep restriction, sleepiness was increased, participants took longer to brake, missed more braking events, and crashed more often. Brain activity showed more intense alpha burst activity and significant changes in EEG spectral power frequencies related to arousal (e.g., delta, theta, alpha). Importantly, increases in amplitude and number of alpha bursts predicted delays in reaction time when braking.

CONCLUSIONS

The findings of this study suggest that a single night of mild sleep loss has significant, negative consequences on driving performance and vigilance, and a clear impact on the physiology of the brain in ways that reflect reduced arousal.

SIGNIFICANCE

Understanding neural and cognitive changes associated with sleep loss may lead to important advancements in identifying and preventing potentially dangerous sleep-related lapses in vigilance.

EEG and behavioural correlates of mild sleep deprivation and vigilance

OBJECTIVE

The current study investigated the behavioral, cognitive, and electrophysiological impact of mild (only a few hours) and acute (one night) sleep loss via simultaneously recorded behavioural and physiological measures of vigilance.

METHODS

Participants (N = 23) came into the lab for two testing days where their brain activity and vigilance were recorded and assessed. The night before the testing session, participants either slept from 12am to 9am (Normally Rested), or from 1am to 6am (Sleep Restriction).

RESULTS

Vigilance was reduced and sleepiness was increased in the Sleep Restricted vs. Normally Rested condition, and this was exacerbated over the course of performing the vigilance task. As well, sleep restriction resulted in more intense alpha bursts. Lastly, EEG spectral power differed in Sleep Restricted vs. Normally Rested conditions as sleep onset progressed, particularly for frequencies reflecting arousal (e.g., delta, alpha, beta).

CONCLUSIONS

The findings of this study suggest that only one night of mild sleep loss significantly increases sleepiness and, importantly, reduces vigilance. In addition, this sleep loss has a clear impact on the physiology of the brain in ways that reflect reduced arousal.

SIGNIFICANCE

Understanding the neural correlates and cognitive processes associated with loss of sleep may lead to important advancements in identifying and preventing deleterious or potentially dangerous, sleep-related lapses in vigilance.

Sustained vigilance is negatively affected by mild and acute sleep loss reflected by reduced capacity for decision making, motor preparation, and execution

Study Objectives

The behavioral and cognitive consequences of severe sleep deprivation are well understood. Surprisingly, relatively little is known about the neural correlates of mild and acute sleep restriction on tasks that require sustained vigilance for prolonged periods of time during the day.

Methods and Results

Event-related potential (ERP) paradigms can reveal insight into the neural correlates underlying visual processing and behavioral responding that is impaired with reduced alertness, as a consequence of sleep loss. Here, we investigated the impact of reduced vigilance following at-home mild sleep restriction to better understand the associated behavioral consequences and changes in information processing revealed by ERPs. As expected, vigilance was reduced (e.g. increased lapses and response slowing) that increased over the course of the experiment in the "sleep restricted" (5 hr sleep) compared with the "sleep-extension" (9 hr sleep) condition. Corresponding to these lapses, we found decreased positivity of visually evoked potentials in the Sleep Restriction vs. Sleep Extension condition emerging from 316 to 449 ms, maximal over parietal/occipital cortex. We also investigated electrophysiological signs of motor-related processing by comparing lateralized readiness potentials (LRPs) and found reduced positivity of LRPs in the Sleep Restriction vs. Sleep Extension condition at 70-40 ms before, and 115-158 ms after a response was made.

Conclusions

These results suggest that even a single night of mild sleep restriction can negatively affect vigilance, reflected by reduced processing capacity for decision making, and dulls motor preparation and execution.

Insufficient Sleep Syndrome: Is it time to classify it as a major noncommunicable disease?

Over the last three to four decades, it has been observed that the average total number of hours of sleep obtained per night by normal individuals have decreased. Concomitantly, global figures indicate that insufficient sleep is associated with serious adverse health and social outcomes. Moreover, insufficient sleep has been linked to seven of the fifteen leading causes of death. Additionally, current evidence suggests that sleep plays a significant role in determining cognitive performance and workplace productivity. There is a great need for a systematic analysis of the economic impact of insufficient sleep, particularly given current evidence that this phenomenon, as well as the poor sleep hygiene practices which produce it, is increasing worldwide. This paper takes the view that health authorities around the world need to raise the general awareness of benefits of sleep. There is considerable scope for research into both the public health impact as well as the macroeconomic consequences of insufficient sleep syndrome (ISS). Additionally, various models which estimate the undiagnosed burden of ISS on the GDP (gross domestic product) are needed to prioritize health issues and to highlight the national policies that are necessary to combat this medical problem. Sleep insufficiency has been declared to be a 'public health epidemic'; therefore, we propose ISS as a potential noncommunicable disease. This review elaborates on this topic further, exploring the causes and consequences of insufficient sleep, and thus providing a perspective on the policies that are needed as well as the research that will be required to support and justify these policies.

What do hypnotics cost hospitals and healthcare?

Hypnotics (sleeping pills) are prescribed widely, but the economic costs of the harm they have caused have been largely unrecognized. Randomized clinical trials have observed that hypnotics increase the incidence of infections. Likewise, hypnotics increase the incidence of major depression and cause emergency admissions for overdoses and deaths.  Epidemiologically, hypnotic use is associated with cancer, falls, automobile accidents, and markedly increased overall mortality.  This article considers the costs to hospitals and healthcare payers of hypnotic-induced infections and other severe consequences of hypnotic use. These are a probable cause of excessive hospital admissions, prolonged lengths of stay at increased costs, and increased readmissions. Accurate information is scanty, for in-hospital hypnotic benefits and risks have scarcely been studied -- certainly not the economic costs of inpatient adverse effects.  Healthcare costs of outpatient adverse effects likewise need evaluation. In one example, use of hypnotics among depressed patients was strongly associated with higher healthcare costs and more short-term disability. A best estimate is that U.S. costs of hypnotic harms to healthcare systems are on the order of $55 billion, but conceivably might be as low as $10 billion or as high as $100 billion. More research is needed to more accurately assess unnecessary and excessive hypnotics costs to providers and insurers, as well as financial and health damages to the patients themselves.

Endothelin-1 mediates attenuated carotid baroreceptor activity by intermittent hypoxia

The objectives of the present study were to examine the effects of intermittent hypoxia (IH) on arterial baroreflex function and assess the underlying mechanism(s). Experiments were performed on adult male rats treated with 14 days of IH (15 s of hypoxia, 5 min of normoxia; 8 h/day) or normoxia (control). Arterial blood pressures were elevated in IH-treated rats, and this effect was associated with attenuated heart rate and splanchnic sympathetic nerve responses to arterial baroreflex activation. In IH-treated rats, carotid baroreceptor responses to elevated sinus pressures were attenuated. Endothelin-1 (ET-1) levels were elevated in the carotid sinus region of IH-treated rats, and this effect was associated with increased endothelin converting enzyme (ECE) activity, which generates biologically active ET-1. ET(A) receptor antagonist prevented the effects of IH on carotid baroreceptor activity. In IH-treated rats, reactive oxygen species (ROS) levels were elevated in the carotid sinus region, and antioxidant treatment prevented the effects of IH on ET-1 levels, ECE activity, carotid baroreceptor activity, and baroreflex function. These results demonstrate that 1) IH attenuates arterial baroreflex function, which is in part due to reduced carotid baroreceptor responses to elevated carotid sinus pressure, and 2) IH-induced carotid baroreceptor dysfunction involves reactive oxygen species-dependent upregulation of ET-1 signaling in the carotid sinus region.

Genioglossus advancement and hyoid myotomy in treating obstructive sleep apnoea syndrome - A follow-up study

AIM

To assess the success of genioglossus advancement and hyoid myotomy in the obstructive sleep apnoea syndrome (OSAS) therapy by comparing pre- and postoperative respiratory values during sleep. One of the surgical methods of widening the upper airways is to advance the spina mandibulae together with the genioglossus insertion. Thus the whole tongue is advanced, including its base. Hyoid myotomy itself, leads to a very unaesthetic filling up of soft tissues in the submental space. Therefore, the original window method of genioglossus advancement was modified and the so-called tenon and mortise genioplasty according to Delaire was applied.

PATIENTS AND METHODS

Thirty-one patients underwent genioglossus advancement by the modified genioplasty with hyoid myotomy (8 women and 23 men, mean age 53.2 years; range 35-69 years). Basic polysomnographic parameters were monitored (during sleep) before surgery and 7.3 months (range 3-6 months) postoperatively.

RESULTS

The cumulative success rate was 74%. Subjective assessment of daily sleepiness using the Epworth scale dropped from preoperative 9.6 to 4.7. The average respiratory disturbance index decreased from 20.9 preoperatively to 10.3, the oxygen desaturation index dropped from 15.1 to 8.8, the average preoperative values of baseline oxygen saturation and average desaturation values had been 95.1% and 86.5%, respectively, and had increased postoperatively to 96.0% and 90.3%, respectively. On the average, preoperative desaturation lasted 36.7s whereas it lasted for 31.0 s postoperatively.

CONCLUSION

Polysomonographic monitoring proved that changing the upper airways can favourably impact upon respiratory parameters during sleep in OSAS.

Preliminary Findings from a Prospective, Randomized Trial of Two Tongue-Base Surgeries for Sleep-Disordered Breathing

OBJECTIVES: This study compares the efficacy of 2 tongue-base surgical procedures in the treatment of patients with moderate to severe sleep-disordered breathing.

STUDY DESIGN AND SETTING: We conducted a prospective, randomized crossover surgical trial at a university hospital.

METHODS: Seventeen patients with moderate to severe sleep-disordered breathing and Fujita type II upper airway collapse for whom conservative treatment failed were enrolled into an institutional review board-approved surgical protocol. They were randomly assigned to undergo palatopharyngoplasty combined with either tongue advancement (mandibular osteotomy) or tongue suspension. Parameters assessed included severity of sleep-disordered breathing (polysomnography), sleepiness (Epworth Sleepiness Scale), and anatomic changes (upper airway endoscopy), as well as demographic factors. Patients not achieving satisfactory improvement in their condition were offered nonsurgical management or additional surgical treatment that varied based on the postoperative assessment but included crossing over to the other tongue surgical procedure.

RESULTS: Nine of the 17 patients were randomized to the tongue suspension group, and 8 to the tongue advancement group. In the 9 tongue suspension patients, Epworth Sleepiness Scale scores fell from 12.1 to 4.1 ( P = 0.007). Airway collapse for all 9 patients measured on Müller maneuver improved, by a mean of 64% ( P = 0.0006) at the palate and 83% ( P = 0.0003) at the base of the tongue. In the 8 tongue advancement patients, Epworth Sleepiness Scale scores fell from a mean of 13.3 to 5.4 ( P = 0.004). Airway collapse for 5 of 8 patients measured on Müller maneuver improved by a mean of 31% ( P = 0.1) at the palate and 75% ( P = 0.03) at the base of the tongue.

CONCLUSION: Prospective, randomized trials of tongue-base surgery for sleep-disordered breathing are possible. Preliminary findings from the current protocol reveal a slight advantage of tongue suspension over tongue advancement.