I think I'm sleepy, therefore I am - Awareness of sleepiness while driving: A systematic review.

Driver drowsiness contributes to 10-20% of motor vehicle crashes. To reduce crash risk, ideally drivers would be aware of the drowsy state and cease driving. The extent to which drivers can accurately identify sleepiness remains under much debate.

Human REM sleep: influence on feeding behaviour, with clinical implications.

Rapid eye movement (REM) sleep shares many underlying mechanisms with wakefulness, to a much greater extent than does non-REM, especially those relating to feeding behaviours, appetite, curiosity, exploratory (locomotor) activities, as well as aspects of emotions, particularly 'fear extinction'. REM is most evident in infancy, thereafter declining in what seems to be a dispensable manner that largely reciprocates increasing wakefulness. However, human adults retain more REM than do other mammals, where for us it is most abundant during our usual final REM period (fREMP) of the night, nearing wakefulness.

Driving drowsy also worsens driver distraction.

Objectives: Laboratory-based studies show that drowsiness increases the propensity to become distracted. As this phenomenon has not been investigated in drowsy drivers, we underwent a pilot study under realistic monotonous driving conditions to see if distraction was more apparent when drowsy; if so, how does it affect driving performance?

Methods: A repeated measures counterbalanced design whereby participants drove for two hours in a fully interactive car simulator during the bi circadian afternoon drive, after a night of either normal (baseline) or restricted sleep to five hours (sleep restriction). Videos of drivers' faces were analysed blind for short (<3 s) and long (>3 s) distractions, in which drivers took their eyes off the road ahead.

Driver sleepiness-comparisons between young and older men during a monotonous afternoon simulated drive.

Young men figure prominently in sleep-related road crashes. Non-driving studies show them to be particularly vulnerable to sleep loss, compared with older men. We assessed the effect of a normal night's sleep vs.

Moderate sleep restriction in treated older male OSA participants: greater impairment during monotonous driving compared with controls.

Objectives: To examine the effects on monotonous driving of normal sleep versus one night of sleep restriction in continuous positive airway pressure (CPAP) treated obstructive sleep apnoea (OSA) patients compared with age matched healthy controls.

Methods: Nineteen CPAP treated compliant male OSA patients (OSA-treated patients (OPs)), aged 50-75 years, and 20 healthy age-matched controls underwent both a normal night's sleep and sleep restriction to 5h (OPs remained on CPAP) in a counterbalanced design. All participants completed a 2h afternoon monotonous drive in a realistic car simulator.

One night's CPAP withdrawal in otherwise compliant OSA patients: marked driving impairment but good awareness of increased sleepiness.

Purpose: Obstructive sleep apnoea (OSA) patients effectively treated by and compliant with continuous positive air pressure (CPAP) occasionally miss a night's treatment. The purpose of this study was to use a real car interactive driving simulator to assess the effects of such an occurrence on the next day's driving, including the extent to which these drivers are aware of increased sleepiness.

Methods: Eleven long-term compliant CPAP-treated 50-75-year-old male OSA participants completed a 2-h afternoon, simulated, realistic monotonous drive in an instrumented car, twice, following one night: (1) normal sleep with CPAP and (2) nil CPAP.

PVT lapses differ according to eyes open, closed, or looking away.

Study Objectives: A lapse during the psychomotor vigilance task (PVT) is usually defined as a response longer than 500 ms; however, it is currently unknown what psychobiological phenomena occur during a lapse. An assessment of what a participant is doing during a lapse may depict varying levels of "disengagement" during these events and provide more insight into the measurement of both a lapse and sleepiness.

Design: Repeated measures.

Evaluating the two-component inspection model in a simplified luggage search task.

Visual inspection of X-ray images of luggage is a time-pressured task that typically shows large initial training effects, but there exists a paucity of models capable of evaluating performance and speed concurrently. In the present study, visual inspection ability during learning was modeled using Drury's two-component inspection model (TCM; Drury, 1975) in a laboratory experiment involving 12 younger (mean age=20.8 years) and 12 older (mean age=60.

Self-reported 'sleep deficit' is unrelated to daytime sleepiness.

Seemingly, many healthy adults have accrued a sleep debt, as determined by findings based on the multiple sleep latency test (MSLT). However, our recent, extensive survey found self-reported sleep deficit was not linked to daytime sleepiness determined by the Epworth sleepiness scale (ESS). Here, we report on the link between self-reported sleep deficit and gold standard measures of sleepiness: MSLT, Psychomotor vigilance test (PVT) and Karolinska Sleepiness Scale (KSS).

Placebo response to caffeine improves reaction time performance in sleepy people.

Caffeine is the most widely used stimulant to counteract sleepiness. However, little is known about any placebo effect of caffeine in sleepy people and the effect of suggestibility. Over a 95 min test period, and in a counterbalanced design, 16 young healthy adults underwent 3 x 30 min sessions at the psychomotor vigilance test (PVT), during an early afternoon 'dip' enhanced by a prior night's sleep restriction (5 h).

Do we really want more sleep? A population-based study evaluating the strength of desire for more sleep.

Objective: The sleep literature increasingly points to an apparent chronic sleep debt in the general population. We investigated this by examining perceived shortfalls in daily sleep, using more indirect questioning methods.

Methods: To determine perceived sleep deficits, 10,810 adults completed a simple questionnaire, which avoided leading questions and provided information on sleep length, daytime sleepiness, desired sleep length, a choice of attractive daytime activities in a "free hour", and "stressful lifestyle".

Mobile phone 'talk-mode' signal delays EEG-determined sleep onset.

Mobile phones signals are pulse-modulated microwaves, and EEG studies suggest that the extremely low-frequency (ELF) pulse modulation has sleep effects. However, 'talk', 'listen' and 'standby' modes differ in the ELF (2, 8, and 217Hz) spectral components and specific absorption rates, but no sleep study has differentiated these modes. We used a GSM900 mobile phone controlled by a base-station simulator and a test SIM card to simulate these three specific modes, transmitted at 12.

Sleepiness enhances distraction during a monotonous task.

Study Objectives: Although sleepiness appears to heighten distraction from the task at hand, especially if the latter is dull and monotonous, this aspect of sleep loss has not been assessed in any systematic way. Distractions are a potential cause of performance lapses (as are micro-sleeps). Here, we investigate the effects of sleepiness on a monotonous task, with and without distraction.

Early evening low alcohol intake also worsens sleepiness-related driving impairment.

Following night-time sleep restriction, afternoon driving performance during the bi-circadian surge in afternoon sleepiness is markedly worsened by blood alcohol concentrations (BACs) well under most national driving limits. This study assessed how driving with this same sleep restriction and BACs (av 40 mg and 28 mg alcohol/100 ml blood at the beginning and end of drive, respectively) respond during the evening circadian rise in alertness. In a 2 x 2 (alcohol versus control drink [double blind] x normal night sleep versus sleep restricted), repeated-measures design, eight healthy young men drove for 2 h from 18:00 h, in a real-car simulator, on a monotonous, simulated highway.

Sleepiness combined with low alcohol intake in women drivers: greater impairment but better perception than men?

Objectives: We have previously shown that low blood alcohol concentrations (BAC) (at approximately half the legal driving limit in both the United Kingdom and in most states in the United States) exacerbate moderate sleepiness (sleep during the night restricted to 5 hours) and markedly impair driving ability in young men. There are distinct physiologic sex differences in the absorption, metabolism, and central nervous system effects of alcohol; therefore, we replicated this earlier study, this time using women and using similar BAC to provide a comparison.

Design: 2 x 2 repeated-measures counterbalanced.

Nonlinear analysis of EEG during NREM sleep reveals changes in functional connectivity due to natural aging.

The spatial organization of nonlinear interactions between different brain regions during the first NREM sleep stage is investigated. This is achieved via consideration of four bipolar electrode derivations, Fp1F3, Fp2F4, O1P3, O2P4, which are used to compare anterior and posterior interhemispheric interactions and left and right intrahemispheric interactions. Nonlinear interdependence is detected via application of a previously written algorithm, along with appropriately generated surrogate data sets.

Presleep relaxed 7-8 Hz EEG from left frontal region: marker of localised neuropsychological performance?

Others have shown that frontally dominant EEG activity of around 7-8 Hz is linked to ongoing cognitive performance. Interestingly, we have found that this EEG activity is particularly evident during the relatively artefact-free period following "lights out" at bedtime when people report "thinking" when lying relaxed in their own beds prior to the appearance of EEG-determined sleepiness. Here, we explore the extent to which this localised activity is indicative of 'trait' performance on left frontal neuropsychological tasks, as well as with less localised, more general tasks.

Electroencephalographic activities during wakefulness and sleep in the frontal cortex of healthy older people: links with "thinking".

Study Objective: Separate studies have shown for the frontal cortex that: i) sleep electroencephalogram (EEG) activity less than 1 Hz may be linked to waking recovery, and ii) waking frontal theta activity may reflect "cortical workload." We explored the potential linkage between (i) and (ii) in relation to specific waking theta frequencies and 0.5-Hz to 1.

Awareness of sleepiness when driving.

The extent to which sleepy drivers are aware of sleepiness has implications for the prevention of sleep-related crashes, especially for drivers younger than 30 years old who are most at risk. Using a real car interactive simulator, we report on EEG, subjective sleepiness, and lane drifting (sleepiness-related driving impairment) from 38 sleep-restricted, healthy young adults undergoing nontreatment control conditions from three (unpublished) investigations using the same experimental protocols for assessing various drinks intended to alleviate sleepiness. Participants drove 2 h during midafternoon under monotonous conditions.

Prefrontal cortex: links between low frequency delta EEG in sleep and neuropsychological performance in healthy, older people.

Low frequency (< 1 Hz) delta EEG in sleep is of increasing interest as it indicates cortical reorganization, especially in the prefrontal cortex (PFC). Other research shows that delta power in sleep is positively linked to waking cerebral metabolic rate. Such findings suggest that < 1 Hz activity may reflect waking performance at neuropsychological tests specific to the PFC.