sleep design for america. statistics/online resources

SLEEPDESIGN FOR AMERICA

STATISTICS/ONLINE RESOURCES

http://drowsydriving.org/about/facts-and-stats/

http://www.cdc.gov/features/dsdrowsydriving/

https://en.wikipedia.org/wiki/Sleep-deprived_driving

http://www.nhtsa.gov/people/injury/drowsy_driving1/Drowsy.html

https://www.fhwa.dot.gov/publications/publicroads/99janfeb/effects.cfm

http://www.discovery.com/tv-shows/mythbusters/about-this-show/tired-vs-drunk-driving/

http://healthysleep.med.harvard.edu/need-sleep/whats-in-it-for-you/judgment-safety
















CONTENTS

Sleep: An Overview The Basics

Circadian Rhythms

Sleep Stages

Functions of Sleep

Sleep Disorders

Measuring Sleepiness

Sleep Deprivation

Shift Workers & Sleep

Driving and Sleep Deprivation

Short Term Solution: Preventing Sleepiness

Long Term Solution: Altering Circadian Rhythms

SLEEP: AN OVERVIEW

The Basics

Circadian Rhythms

Sleep Stages

Functions of Sleep

Sleep Disorders

SLEEP: THE BASICS PART 1

As an organism falls asleep body temperature, heart rate, breathing rate, and energy use all decrease. Brain waves get slower and bigger.

Sleep can accrue debt to a certain point (if you skip a night’s sleep, you will sleep longer the next night, but you will not sleep so long that you make up for the lost sleep completely)

Sleep consists of 4 stages: Stage 1, Stage 2, Stage 3, and REM From here on will be referred to as N1, N2, N3, REM

When we sleep, we move through these stages in cycles. Usually like this: N1 → N2 → N3 → N2 → REM

Each full cycle takes approximately 90 minutes

We complete 4-5 full cycles each night (depending on total sleep time)

In the beginning of the night, we spend more time in stages N2 & N3, and less time in REM. Towards the end of the night/morning, we spend less time in N2&N3, and more time in REM.

SLEEP THE BASICS: CIRCADIAN RHYTHMS The need for sleep increases as time from last sleep increases.

Sleeping times are influenced by: the circadian rhythms, time since last sleep, and desire to sleep/chosen behavior

Circadian rhythms are influenced by the circadian clock. The circadian clock is ‘located’ in the suprachiasmatic nucleus in the thalamus, however many tissues have been shown to follow a circadian rhythm independent of the SCN

Essentially, the body is entrained to match sleep cycles to the sun, where we begin preparing for sleep when the sun goes down and our body prepares for wakefulness as the sun comes up. This is a ‘natural’ circadian rhythm.

Even in the absence of light, our bodies follow circadian rhythms. Body temperature and hormones are continually adjusted by the body, body can still ‘tell time’ without light.

The most important of these hormones is melatonin, but others such as HGF and cortisol have important implications for sleep’s impact on health

Most humans run on a 25 hour cycle, slightly longer than the 24 hour day.

A healthy young adult entrained to the sun will (during most of the year) fall asleep a few hours after sunset, experience body temperature minimum at 6AM, and wake up a few hours after sunrise.

Before artificial light, most people slept early, took a brief period of wake in the middle of the night, and then slept again until sunrise.

SLEEP: THE BASICS PART 3

Sleeping at the wrong time of day is not as restorative. Timing is correct when the following occur after the middle of the sleep episode and before awakening: maximum concentration of and minimum core body temperature.

People experience two periods of intense sleepiness every 24 hours, about 12 hours apart. This is why some people feel sleepy in the afternoon and some countries have ‘siesta’. If you usually feel sleepy around 12am, you will probably also feel sleepy around 12pm. Your circadian clock often overrides this feeling in the afternoon, and in the morning this sleepiness encourages you to sleep a little longer/reduces change of awakening too early.

A person’s need for sleep varies by age and individual needs. Teens need 7-10 hours on average. Some people need more or less.

Adults need 8-9 hours, on average. Some people need more or less.

SLEEP STAGES

Non-REM Sleep N1 – the lightest stage of sleep. Participants often shift in and out of N1 and wakefulness at this

time. If woken up, they often do not believe they were asleep. Muscles relax, person may twitch or jerk. Characterized by alpha and theta waves.

N2- characterized by sleep spindles and K-complexes (types of brain activity). People become fully unconscious.

N3- aka deep sleep or slow wave sleep. This stage more than others contributes to feeling “rested”. This is the stage in which parasomnias occur (sleepwalking, night terrors, etc.)

REM Sleep Rapid Eye Movement sleep. The stage in which dreaming occurs. Person’s muscles are paralyzed.

FUNCTIONS OF SLEEP (STILL DEBATED)

Clearing waste from the brain, including those thought to be related to dementia

Brain development

Memory consolidation N2 & N3 are important for memory for facts and life episodes.

REM is important for procedural/motor memory and complex tasks

Emotion regulation

SLEEP DISORDERS Sleep Apnea: a person will wake frequently during the night because they are having

trouble breathing. They are not aware of their arousals. These arousals prevent them from spending significant time in the deeper stages of sleep, and can therefore contribute to cognitive deficits

Insomnia: difficulty falling asleep, staying asleep, or waking too early in the morning. Results in decreased sleep time against a person’s best efforts

Delayed Sleep Phase Syndrome: teens often are ‘night owls’. People with DSPS are either extreme night owls (cannot sleep early and then sleep in late) or they do not grow out of being night owls and it affects their daily lives negatively

Non-24 Hour Disorder: people whose natural sleep cycle ‘feels’ like it should be significantly longer than 24/25 hours. These people experience trouble keeping a regular schedule, because every day they don’t feel tired until several hours later than they went to sleep the previous night. This is especially difficult to live with.

MEASURING SLEEPINESS


An average latency to sleep of between 5 to 10 minutes is considered an intermediate level of sleepiness, and average latencies greater than10 minutes are considered to represent low levels of physiologic sleepiness. data from simulated shift work studies suggest that average MSLT sleep latencies are lower during the biologic Night. Other indicators of physiologic sleepiness include EEG measures of alpha (8–12 Hz) and theta (4–8 Hz) activity,55 slow eye movements,56 or blink duration.

relation between subjective sleepiness measured with the Karolinska Sleepiness Scale (KSS) and blink duration (BLINKD) and lane drifting calculated as the standard deviation of the lateral position (SDLAT) in a high-fidelity moving base driving simulator. Five male and five female shift workers were recruited to participate in a 2-h drive (08:00–10:00 hours) after a normal night sleep and after working a night shift. significant (P < 0.001) effect of the KSS for both dependent variables. A test for a quadratic trend suggests a curvilinear effect with a steeper increase at high KSS levels for both SDLAT (P < 0.001) and BLINKD (P ¼ 0.003). Large individual differences were observed for the intercept (P < 0.001), suggesting that subjects differed in their overall driving performance and blink duration independent of sleepiness levels.


Several researchers have investigated the relation between vigilance and ocular variables such as saccade, slow eye movement, pupil, blink, or eyelid closure. This study was undertaken to find the most effective indicator among these ocular variables for evaluating short-term (1 min) fluctuation of vigilance, and to investigate the ability of the most effective ocular variable for predicting deteriorated vigilance during behavioral maintenance of the wakefulness test (Oxford sleep resistance test: OSLER test). Decreased blink frequency and pupil diameter as well as increased percentage of eyelid closure time (PERCLOS) and slow eye movement were observed as the consecutive missed responses increased. Among these variables, PERCLOS showed the highest ability to detect occurrence of any missed response and three or more consecutive missed responses. Moreover, a missed response seldom occurred (0.2 ± 0.2/20 trial/min) when PERCLOS was less than 11.5% per minute. Results suggest that, among the ocular variables, PERCLOS can prevent error or accident caused by low vigilance most effectively.

A number of behavioral, physiological, and psychometric tests are being used increasingly to evaluate the impact of fatigue on driver performance. These include the oculography, polysomnography, actigraphy, the maintenance of wakefulness test, and others.

http://www.sciencedirect.com/science/article/pii/S0167876011002789#200018876

SLEEP DEPRIVATION

SLEEP DEPRIVATION

Sleep deprivation increases sleep propensity- reduces time to fall asleep.

Partial sleep deprivation occurs in 3 ways: During sleep fragmentation, the normal progression and sequencing of sleep stages is typically

disrupted to varying degrees, resulting in less time in consolidated physiological sleep, relative to time in bed.

loss of specific physiological sleep stages, and is, therefore, referred to as selective sleep stage deprivation

Sleep deprivation/sleep debt

SLEEP DEPRIVATION

Sleep deprivation to 6 or 4 hours a night for 2 weeks results in significant cognitive deficits. 4hr condition was equivalent to 2 nights without sleep. Psychomotor vigilance test, test of working memory, cognitive throughput, self-reported sleepiness.

Restricting sleep below an individual’s optimal time in bed (TIB) can cause a range of neurobehavioral deficits, including lapses of attention, slowed working memory, reduced cognitive throughput, depressed mood, and perseveration of thought (Banks, 2007)

Prolonged wakefulness greatly decreases nocturnal driving performance.

SHIFT WORKERS & SLEEP


¾ of shift workers suffer from disturbed sleep, which is sleep that is less deep and restful, and features more arousals and periods of wakefulness.

Driving in the early morning is associated with increased accident risk affecting not only professional drivers but also those who commute to work.

Disturbed sleep is #1 predictor of job satisfaction- those with disturbed sleep are less likely to be satisfied with their job.

Night shift workers sleep on average 4-6 hours, 1-4 hours less than they sleep during a normal sleep schedule.

Although some have argued that the main problem in shift working is the changing schedule, others argue that workers who work the night shift consistently get less sleep than those who are on slowly rotating schedules (at least 3 weeks per schedule). Rapid, frequent changes in work/sleep schedule are correlated with less overall sleep.

Sleep loss is primarily stage 2 and REM. Amount of slow wave sleep does not suffer a reduction.


An assumed reason for trouble adjusting to alternate sleep schedule is conflict that occurs when a person is exposed to external light. Complete control over light can facilitate adjusting to a new schedule.

Irregular work schedules often results in a disruption of the normal circadian rhythm that can causes sleepiness when wakefulness is required and insomnia during the main sleep episode.

Working on a rotating daytime shifts causes significant sleep disturbances. As consequences, these workers are more likely to feel sleepy at work and are more likely to have work-related accidents and sick leaves.

strong, acute effects on sleep and alertness in relation to night and morning work. The effects seem, however, to linger and also affect days off. The level of the disturbances is similar to that seen in clinical insomnia and may be responsible for considerable human and economical costs due to fatigue related accidents and reduced productivity. The mechanism behind the disturbances is the sleep interfering properties of the circadian system during day sleep and the corresponding sleep promoting properties during night work. Various strategies may be used to counteract the effects of shift work, such as napping, sufficient recovery time between shifts, clockwise rotation


Shift work has been associated with a number of health problems including cardiovascular disease, impaired glucose and lipid metabolism, gastrointestinal discomfort, reproductive difficulties, and breast cancer.

Fatigue can be caused by extended on-duty and/or waking periods, inadequate sleep quantity, sleep disturbances, disruption of circadian rhythms, and difficult work and familial conditions.

Fatigue-related accidents raise a safety concern for shift workers, especially at the end of the night when the circadian nadir of alertness interacts with increased time awake.

Individuals vary greatly in their capacity to adjust to atypical work schedules and their tolerance to circadian misalignment. Predisposing individual and domestic factors have been identified, such as increasing age, being a single woman in charge of children, and split sleep patterns, all of which can affect the ability to adjust to atypical schedules.


The purpose of this study is to describe the prevalence of drowsy driving episodes and the relationship between drowsy driving and nurse work hours, alertness on duty, working at night, and sleep duration. Almost 600 of the nurses (596/895) reported at least 1 episode of drowsy driving, and 30 nurses reported experiencing drowsy driving following every shift worked. Shorter sleep durations, working at night, and difficulties remaining awake at work sig nificantly increased the likelihood of drowsy driving episodes.

Shift work, like chronic jet lag, is known to disrupt workers’ normal circadian rhythms and social life, and to be associated with increased health problems (eg, ulcers, cardiovascular disease, metabolic syndrome, breast cancer, reproductive difficulties) and with acute effects on safety and productivity

The aim of this study was to assess the chronicity and reversibility of the effects of shift work on cognition


3232 employed and retired workers (participation rate: 76%) who were 32, 42, 52 and 62 years old at the time of the first measurement (t1, 1996), and who were seen again 5 (t2) and 10 (t3) years later. 1484 of them had shift work experience at baseline (current or past) and 1635 had not. The main outcome measures were tests of speed and memory, assessed at all three measurement times. Results Shift work was associated with impaired cognition. The association was stronger for exposure durations exceeding 10 years (dose effect; cognitive loss equivalent to 6.5 years of age-related decline in the current cohort). The recovery of cognitive functioning after having left shift work took at least 5 years (reversibility).

DRIVING AND SLEEP DEPRIVATION

DRIVING & SLEEP DEPRIVATION

An epidemiological study found an increased incidence of sleep-related crashes in drivers reporting <7 h of sleep per night on average

Studies have shown that a large proportion of traffic accidents around the world are related to inadequate or disordered sleep. Recent surveys have linked driver fatigue to 16% to 20% of serious highway accidents in the UK, Australia, and Brazil.

Fatigue as a result of sleep disorders (especially obstructive sleep apnea), excessive workload and lack of physical and mental rest, have been shown to be major contributing factors in motor vehicle accidents

DRIVING & SLEEP DEPRIVATION Additional contributing factors to these crashes included poor sleep quality, dissatisfaction

with sleep duration (i.e., undersleeping), daytime sleepiness, previously driving drowsy, amount of time driving and time of day (i.e., driving late at night)

Studies have also examined the effects of sleep restriction on performance on various driving simulators. It has been found that driving performance decreased (e.g., more crashes) and subjectively reported sleepiness increased when sleep was restricted to between 4 and 6 h per night.

The present study used a driving simulator to investigate the effects of driving home from a night shift. Ten shift workers participated after a normal night shift and after a normal night sleep. The results showed that driving home from the night shift was associated with an increased number of incidents (two wheels outside the lane marking, from 2.4 to 7.6 times), decreased time to first accident, increased lateral deviation (from 18 to 43 cm), increased eye closure duration (0.102 to 0.143 s), and increased subjective sleepiness.


The objective of this study was to analyze the EEG changes in fatigued subjects while performing a simulated driving task. After a night of sleep deprivation, eight subjects were given a dose of caffeine to reduce drowsiness. During about 50 min of continuous driving, car movements and subject behaviors were recorded on video cameras, and 8 channels of EEG were also recorded. EEG activity was significantly different between groups.

Twenty human subjects underwent driving simulations with EEG monitoring. Alert EEG was marked by dominant beta activity, while drowsy EEG was marked by alpha dropouts. The duration of eye blinks corresponded well with alertness levels associated with fast and slow eye blinks. Samples of EEG data from both states were used to train the SVM program by using a distinguishing criterion of 4 frequency features across 4 principal frequency ands. The trained SVM program was tested on unclassified EEG data and subsequently checked for concordance with manual classification. The classification accuracy reached 99.3%. The SVM program was also able to predict the transition from alertness to drowsiness reliably in over 90% of data samples. This study shows that automatic analysis and detection of EEG changes is possible by SVM and SVM is a good candidate for developing pre-emptive automatic drowsiness detection systems for driving safety.

DRIVING & SLEEP DEPRIVATION Thus, countermeasure device is currently required in many fields for sleepiness related accident

prevention. This paper intends to perform the drowsiness prediction by employing Support Vector Machine (SVM) with eyelid related parameters extracted from EOG data collected in a driving simulator provided by EU Project SENSATION. The dataset is firstly divided into three incremental drowsiness levels, and then a paired t-test is done to identify how the parameters are associated with drivers’ sleepy condition. With all the features, a SVM drowsiness detection model is constructed. The validation results show that the drowsiness detection accuracy is quite high especially when the subjects are very sleepy.

This paper describes a real-time prototype computer vision system for monitoring driver vigilance. The main components of the system consists of a remotely located video CCD camera, a specially designed hardware system for real-time image acquisition and for controlling the illuminator and the alarm system, and various computer vision algorithms for simultaneously, real-time and non-intrusively monitoring various visual bio-behaviors that typically characterize a driver’s level of vigilance. The visual behaviors include eyelid movement, face orientation, and gaze movement (pupil movement). The system was tested in a simulating environment with subjects of different ethnic backgrounds, different genders, ages, with/without glasses, and under different illumination conditions, and it was found very robust, reliable and accurate

Fatigue can be equally studied in real and simulated environments but reaction time and self-evaluation of sleepiness are more affected in a simulated environment. Real driving and driving simulators are comparable for measuring line crossings but the effects are of higher amplitude in the simulated condition. Driving simulator may need to be calibrated against real driving in various condition.


Sleepiness may be a factor in about 20% of motor vehicle accidents and studies carried out in controlled environments suggest that the most common changes in driving performance attributable to sleepiness include increased variability of speed and lateral lane position. Higher-order functions including judgment and risk taking may also deteriorate.

Moreover, prolonging wakefulness even by a few hours may produce deterioration in driving performance comparable to that seen in drivers with blood alcohol concentrations at levels deemed dangerous by legislation.

The majority of prevention efforts to date have focused on short-term solutions that only mask underlying sleepiness and it is suggested that more emphasis be directed toward primary prevention efforts such as educating drivers about the importance of getting sufficient sleep and avoiding circadian performance troughs.


Falling asleep at the wheel is a common cause of road accidents, but little is known about the extent to which drivers are aware of their sleepiness prior to such accidents. 28 healthy young adult experienced drivers, sleep restricted the night before drove for 2 h in the afternoon in an interactive real-car simulator incorporating a dull and monotonous roadway. Lane drifting, typifying sleepy driving, was subdivided into minor and major incidents, where the latter was indicative of actually falling asleep. A distinction was made between the subjective perceptions of sleepiness and the likelihood of falling asleep which drivers reported separately. Increasing sleepiness was closely associated with an increase in the number of incidents. Major incidents were preceded by self-awareness of sleepiness well beforehand and typically, subjects reached the stage of fighting sleep when these incidents happened. Whilst the perceived likelihood of falling asleep was highly correlated with increasing sleepiness, some subjects failed to appreciate that extreme sleepiness is accompanied by a high likelihood of falling asleep. It was not possible for our subjects to fall asleep at the wheel and have an “accident” without experiencing a sustained period of increasing sleepiness, of which they were quite aware. There is a need to educate at least some drivers that extreme sleepiness is very likely to lead to falling asleep and a high accident risk.

PREVENTING SLEEPINESS

SHORT TERM STRATEGY: PREVENTING SLEEPINESS

Objective: The objective of this study was to investigate if a verbal task can improve alertness and if performance changes are associated with changes in alertness as measured by EEG. Background: Previous research has shown that a secondary task can improve performance on a short, monotonous drive. The current work extends this by examining longer, fatiguing drives. The study also uses EEG to confirm that improved driving performance is concurrent with improved driver alertness. Method: A 90-min, monotonous simulator drive was used to place drivers in a fatigued state. Four secondary tasks were used: no verbal task, continuous verbal task, late verbal task, and a passive radio task. Results: When engaged in a secondary verbal task at the end of the drive, drivers showed improved lane-keeping performance and had improvements in neurophysiological measures of alertness. Conclusion: A strategically timed concurrent task can improve performance even for fatiguing drives.


The aim of this study is to determine whether continuous exposure to monochromatic light in the short wavelengths (blue light), placed on the dashboard, improves night-time driving performance. In this randomized, double-blind, placebo-controlled, cross-over study, 48 healthy male participants (aged 20–50 years) drove 400 km (250 miles) on motorway during night-time. They randomly and consecutively received either continuous blue light exposure (GOLite, Philips, 468 nm) during driving or 2*200 mg of caffeine or placebo of caffeine before and during the break. Treatments were separated by at least 1 week. The outcomes were number of inappropriate line crossings (ILC) and mean standard deviation of the lateral position (SDLP). Eight participants (17%) complained about dazzle during blue light exposure and were removed from the analysis. Results from the 40 remaining participants (mean age ± SD: 32.9±11.1) showed that countermeasures reduced the number of inappropriate line crossings (ILC) (F(2,91.11) = 6.64; p<0.05). Indeed, ILC were lower with coffee (12.51 [95% CI, 5.86 to 19.66], p = 0.001) and blue light (14.58 [CI, 8.75 to 22.58], p = 0.003) than with placebo (26.42 [CI, 19.90 to 33.71]). Similar results were found for SDLP. Treatments did not modify the quality, quantity and timing of 3 subsequent nocturnal sleep episodes. Despite a lesser tolerance, a non-inferior efficacy of continuous nocturnal blue light exposure compared with caffeine suggests that this in-car countermeasure, used occasionally, could be used to fight nocturnal sleepiness at the wheel in blue light-tolerant drivers, whatever their age.

http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0046750#s3


Research on public security, especially the safe manipulation and control of vehicles, has gained increasing attention in recent years. This study proposes a closed-loop drowsiness monitoring and management system that can estimate subjects’ driving performance. The system observes electroencephalographic (EEG) dynamics and behavioral changes, delivers arousing feedback to individuals experiencing momentary cognitive lapses, and assesses the efficacy of the feedback. Results of this study showed that the arousing feedback immediately improved subject performance, which was accompanied by concurrent theta- and alpha-power suppression in the bilateral occipital areas. This study further demonstrated the feasibility of accurately assessing the efficacy of arousing feedback presented to drowsy participants by monitoring the changes in their EEG power spectra.

ALTERING CIRCADIAN RHYTHMS

LONG TERM STRATEGY: ALTERING CIRCADIAN RHYTHMS

delayed weekend sleep pattern caused a 31.6 min delay of the endogenous melatonin rhythm. Melatonin administration counteracted the phase delay of endogenous melatonin onset. On Sunday, melatonin administration increased the sleepiness throughout the evening and reduced sleep onset latency at bedtime. On Monday morning, subjective sleepiness was decreased in the melatonin condition. Conclusion: A delayed weekend sleep pattern did show a mild phase delay effect on the endogenous circadian rhythm. A single dose of melatonin can acutely reverse the weekend drift.

The human circadian system is maximally sensitive to short-wavelength (blue) light. In a previous study we found no difference between the magnitude of phase advances produced by bright white versus bright blue-enriched light using light boxes in a practical protocol that could be used in the real world. Since the spectral sensitivity of the circadian system may vary with a circadian rhythm, we tested whether the results of our recent phase-advancing study hold true for phase delays. These results indicate that at light levels commonly used for circadian phase shifting, blue-enriched polychromatic light is no more effective than the white polychromatic lamps of a lower correlated color temperature (CCT) for phase delaying the circadian clock.


Czeisler et al. first showed that modification of the light-dark cycle could influence the timing of human circadian rhythms 0), but it was initially unclear whether light and dark were acting only indirectly via their effects on sleeping and waking or directly on the circadian pacemaker. Lewy et al. showed that bright light but not ordinary room light is capable of suppressing nocturnal melatonin secretion in humans (2). Similar bright light has subsequently been shown to have antidepressant effects in patients with seasonal affective disorder (winter depression) (3-5) and direct phase-shifting effects in humans (4,6-8). Such phase-shifting properties have been postulated by some researchers to underlie the therapeutic effects of light in seasonal affective disorder (4) and have been suggested to be of potential value in correcting disordered sleep and biological rhythms, such as occur in jet lag, shift work, and delayed sleep phase syndrome


Various strategies have been proposed for preventing or reducing the impact of fatigue on motor vehicle accidents. These have included: Educational programs emphasizing the importance of restorative sleep and the need for drivers to recognize the presence of fatigue symptoms, and to determine when to stop to sleep; The use of exercise to increase alertness and to promote restorative sleep; The use of substances or drugs to promote sleep or alertness (i.e. caffeine, modafinil, melatonin and others), as well as specific sleep disorders treatment; The use of CPAP therapy for reducing excessive sleepiness among drivers who have been diagnosed with obstructive sleep apnea.

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sleep design for america. statistics/online resources

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