Multimodal in-vehicle lighting system increases daytime light exposure and alertness in truck drivers under Arctic winter conditions.

Drowsiness while driving negatively impacts road safety, especially in truck drivers. The present study investigated the feasibility and alerting effects of a daylight-supplementing in-truck lighting system (DS) providing short-wavelength enriched light before, during, and after driving. In a within-participants design, eight truck drivers drove a fully-loaded truck under wintry Scandinavian conditions (low daylight levels) with a DS or placebo system for five days. Subjective and objective measures of alertness were recorded several times daily, and evening melatonin levels were recorded three times per study condition. DS significantly increased daytime light exposure without causing negative side effects while driving. In addition, no negative carry-over effects were observed on evening melatonin and sleepiness levels or on nighttime sleep quality. Moreover, objective alertness (i.e., psychomotor vigilance) before and after driving was significantly improved by bright light exposure. This effect was accompanied by improved subjective alertness in the morning. This field study demonstrated that DS was able to increase daytime light exposure in low-daylight conditions and to improve alertness in truck drivers before and after driving (e.g., during driving rest periods). Further studies are warranted to investigate the effects of daylight-supplementing in-cabin lighting on driving performance and road safety measures.

Oxidative Stress Reaction to Hypobaric-Hyperoxic Civilian Flight Conditions.

BACKGROUND: In military flight operations, during flights, fighter pilots constantly work under hyperoxic breathing conditions with supplemental oxygen in varying hypobaric environments. These conditions are suspected to cause oxidative stress to neuronal organ tissues. For civilian flight operations, the Federal Aviation Administration (FAA) also recommends supplemental oxygen for flying under hypobaric conditions equivalent to higher than 3048 m altitude, and has made it mandatory for conditions equivalent to more than 3657 m altitude. AIM: We hypothesized that hypobaric-hyperoxic civilian commercial and private flight conditions with supplemental oxygen in a flight simulation in a hypobaric chamber at 2500 m and 4500 m equivalent altitude would cause significant oxidative stress in healthy individuals. METHODS: Twelve healthy, COVID-19-vaccinated (third portion of vaccination 15 months before study onset) subjects (six male, six female, mean age 35.7 years) from a larger cohort were selected to perform a 3 h flight simulation in a hypobaric chamber with increasing supplemental oxygen levels (35%, 50%, 60%, and 100% fraction of inspired oxygen, FiO2, via venturi valve-equipped face mask), switching back and forth between simulated altitudes of 2500 m and 4500 m. Arterial blood pressure and oxygen saturation were constantly measured via radial catheter and blood samples for blood gases taken from the catheter at each altitude and oxygen level. Additional blood samples from the arterial catheter at baseline and 60% oxygen at both altitudes were centrifuged inside the chamber and the serum was frozen instantly at -21 °C for later analysis of the oxidative stress markers malondialdehyde low-density lipoprotein (M-LDL) and glutathione-peroxidase 1 (GPX1) via the ELISA test. RESULTS: Eleven subjects finished the study without adverse events. Whereas the partial pressure of oxygen (PO2) levels increased in the mean with increasing oxygen levels from baseline 96.2 mm mercury (mmHg) to 160.9 mmHg at 2500 m altitude and 60% FiO2 and 113.2 mmHg at 4500 m altitude and 60% FiO2, there was no significant increase in both oxidative markers from baseline to 60% FiO2 at these simulated altitudes. Some individuals had a slight increase, whereas some showed no increase at all or even a slight decrease. A moderate correlation (Pearson correlation coefficient 0.55) existed between subject age and glutathione peroxidase levels at 60% FiO2 at 4500 m altitude. CONCLUSION: Supplemental oxygen of 60% FiO2 in a flight simulation, compared to flying in cabin pressure levels equivalent to 2500 m-4500 m altitude, does not lead to a significant increase or decrease in the oxidative stress markers M-LDL and GPX1 in the serum of arterial blood.

Prospective analyses of alertness, sleep, and fitness to drive one year after de novo multiple sclerosis diagnosis.

BACKGROUND: The prevalence and functional burden of the chronic demyelinating disease multiple sclerosis (MS) are well documented; however, little is known about the initial clinical course of alertness, sleep, cognitive, and psychological symptoms. OBJECTIVES: This exploratory, prospective, longitudinal study multidimensionally investigated the development and progression of alertness, sleep, fitness to drive, and psychological symptoms in the first year after de novo MS diagnosis. METHODS: Twenty-five people with MS (pwMS) were assessed cognitively, psychologically, and using polysomnography soon after diagnosis and one year later, with outcomes compared to matched healthy controls. RESULTS: In the early stage of the disease, psychological symptoms of pwMS were comparable with those of controls, and patient conditions did not deteriorate within the first disease year. A small percentage of pwMS experienced increased levels of anxiety and depression after diagnosis. Alertness, sustained attention, and fitness to drive were comparable between both groups, and fatigue levels remained low over the course of the year. CONCLUSIONS: This study highlights patient experiences within the initial clinical course of MS in a small group of patients. Further research is needed to understand the progression of symptoms and impairments in MS over a longer period and in different stages of the disease.

[Sleep and sleep disorders in old age]. / Schlaf und Schlafstörungen im hohen Lebensalter.

The increasing interruptions of night sleep with normal ageing must be distinguished from sleep disorders. Somatic and psychiatric morbidity as well as medication have a huge impact on sleep. Furthermore, the relationship between sleep and morbidity is mutual. Disturbed sleep modifies the clinical appearance of diseases and morbidity affects the ability to sleep. Especially in geriatric medicine, geriatric syndromes such as falls, depression or dementia are modified by sleep disorders. Therefore, treatment for sleep disorders offers the chance to improve geriatric syndromes.When treating, it is important to identify the individual sleep disorders. Coincidences of different sleep disorders are common in the elderly. The history of a patient in connection with a sleeping diary is the basic diagnostic procedure. Sleep medicine provides further technical methods for further examination. Older people should also be examined in a sleep laboratory if the results have consequences that will be accepted by the patient. However, this should be clarified in advance.

Assessment of sleep and sleep disorders in geriatric patients.

Sufficient and refreshing sleep is important for good health, physical and cognitive functioning as well as quality of life. An assessment of sleep quality and sleep disorders is therefore mandatory in geriatric patients. Despite a variety of clinical assessment tools for screening and diagnosing sleep disorders, only some of them have been validated in older subjects and nearly none in geriatric patients or in individuals with dementia. Therefore, the aim of this review is to present a concise overview of assessment tools for sleep disorders that are widely used in sleep medicine and to briefly discuss the suitability and limitations in geriatric patients and subjects with dementia.

Daytime sleepiness versus fatigue in patients with multiple sclerosis: A systematic review on the Epworth sleepiness scale as an assessment tool.

Fatigue is a frequent and distressing symptom in patients with multiple sclerosis (MS). In contrast, sleepiness, characterized by difficulties to stay awake and alert during the day, seems to be less prevalent in MS; however, exact studies are lacking. In addition, there is a semantic confusion of the concepts of "fatigue" and "sleepiness", which are often used interchangeably. We conducted a systematic review of studies using the Epworth sleepiness scale (ESS) for the assessment of daytime sleepiness in patients with MS. The summarized results of 48 studies demonstrate that sleepiness, as indicated by elevated ESS scores, is less prevalent and less severe than fatigue but is present in a significant proportion of patients with MS. In most cross-sectional and longitudinal studies, there was a moderate association between ESS scores and various fatigue rating scales. Longitudinal studies on the effect of wakefulness-promoting agents failed to show a consistent improvement of sleepiness or fatigue as compared to placebo. It has also been shown that daytime sleepiness is frequently associated with comorbid sleep disorders that are often underrecognized and undertreated in MS. Sleepiness and potential sleep disorders may also precipitate and perpetuate fatigue in patients with MS and should be part of the differential diagnostic assessment. To support an appropriate decision-making process, we propose a stepwise evaluation of sleepiness as compared to fatigue in patients with MS.

The effect of partial sleep deprivation on computer-based measures of fitness to drive.

PURPOSE: Using a partial sleep deprivation paradigm, the aim of the study was to investigate the sensitivity of a computer-based test battery of fitness to drive to detect impairments related to sleepiness. METHODS: Forty-seven healthy subjects (34 females, mean age 26.0 ± 6.8 years) participated in a counterbalanced within-subject design of two conditions: (i) normal night sleep and (ii) partial sleep deprivation (PSD) with 4 h time in bed. For the assessment of fitness to drive, we used a validated traffic psychological test battery. Moreover, well-established measures of sleepiness highly responsive to sleep deprivation were applied: the Karolinska Sleepiness Scale (KSS), pupillography (Pupil Unrest Index (PUI) as physiological sleepiness indicator) and two sustained attention tasks (psychomotor Vigilance Task and Mackworth Clock Test). RESULTS: Subjective and physiological sleepiness were significantly increased after PSD, accompanied by large (d > 1.50 for KSS) and medium (d = 0.55 for PUI) effect sizes. Sleepiness-related performance decrements were found in both sustained attention tasks (d = 0.59-0.77). Assessing driving-related ability, PSD induced decrements only in the test domain Reaction Test (reaction time d = 0.54 and motor time d = 0.45). All other subtests-as well as the overall judgement of fitness to drive-were not significantly affected by PSD. CONCLUSION: In contrast to established tests of sustained attention and subjective sleepiness, computer-based test batteries of fitness to drive might lack sensitivity to core aspects of sleepiness as they mainly consist of short and stimulating subtests. Therefore, tasks that require sustained attention should be an essential part of traffic psychological test batteries when sleepiness is a potential issue.

Impact of overnight traffic noise on sleep quality, sleepiness, and vigilant attention in long-haul truck drivers: Results of a pilot study.

This study aimed to evaluate the impact of traffic noise along the motorway on sleep quality, sleepiness, and vigilant attention in long-haul truck drivers. This was a randomized, crossover, within-subject controlled study. Healthy long-haul truck drivers spent 6 consecutive nights in a real truck berth with full sleep laboratory equipment. During 3 nights, subjects were exposed to replayed traffic noise alongside motorways, whereas the other 3 nights were without traffic noise. Polysomnography was recorded during the nights and numerous sleepiness tests and vigilance examinations were performed during the following standardized working day. Outcome measures were compared between noisy and silent nights using the paired Wilcoxon test. Ten healthy long-haul truck drivers with a mean age of 36.3 ± 7.3 years completed the study as planned. On noisy nights, subjects had greater latencies to the rapid eye movement (REM) phase (90 ± 32 min vs 69 ± 16 min, P = 0.074) and higher percentages of sleep stage 1 (13.7 ± 5.5% vs 11.2 ± 4.4%; P = 0.059). Subjects also rated their sleep quality as having been better during nights without noise (28.1 ± 3.7 vs 30.3 ± 6.2, P = 0.092). The impact of these differences on daytime sleepiness and vigilance was rather low; however, mean Karolinska Sleepiness Scale (KSS) scores measured during the course of the following day were higher on six out of eight occasions after noisy nights. The effects of overnight traffic noise on sleep quality are detectable but unlikely to have any major impact on the vigilant attention and driving performance of long haul-truck drivers with low nocturnal noise sensitivity. This might not be true for subgroups prone to sleeping disorders.

Prevalence of Sleep-Disordered Breathing-Related Symptoms in Patients with Chronic Heart Failure and Reduced Ejection Fraction.

BACKGROUND: Sleep-disordered breathing (SDB) is highly prevalent in patients with chronic heart failure (CHF) and is associated with a poor prognosis. Data on SDB-related symptoms and vigilance impairment in patients with CHF and SDB are rare. Thus, the objective of the present study was to assess a wide spectrum of SDB-related symptoms and objective vigilance testing in patients with CHF with and without SDB. METHODS: Patients with CHF (n = 222; average age, 62 years; left ventricular ejection fraction [LVEF], 34%) underwent polysomnography regardless of the presence or absence of SDB-related symptoms. Patients were stratified into those with no SDB (apnea-hypopnea index [AHI] < 15 episodes/h), moderate SDB (AHI ≥ 15 to < 30 episodes/h), and severe SDB (AHI ≥ 30 episodes/h). A standardized institutional questionnaire assessing a wide spectrum of SDB-related symptoms was applied. A subset of patients underwent objective vigilance testing (Quatember Maly, 100 stimuli within 25 minutes). RESULTS: Daytime fatigue (no SDB, moderate SDB, and severe SDB: 53%, 69%, and 80%, respectively; P = 0.005), unintentional sleep (9%, 15%, and 32%, respectively; P = 0.004), and xerostomia (52%, 49%, and 70%, respectively; P = 0.018), as well as an impaired objective vigilance test result (mean reaction time, 0.516, 0.497, and 0.579 ms, respectively; P < 0.001) occurred more frequently with increasing severity of SDB. Seventy-eight percent of patients with CHF and SDB had at least 3 SDB-related symptoms. In a linear multivariable regression model, the frequency of daytime fatigue (P = 0.014), unintentional sleep (P = 0.001), xerostomia (P = 0.016), and mean reaction time (P = 0.001) were independently associated with increasing AHI independent of age, body mass index, New York Heart Association functional class, and LVEF. CONCLUSIONS: The majority of patients with CHF and SDB have several potential SDB-related symptoms and objective impairment of vigilance as potential treatment targets.

Impaired vigilance is associated with erectile dysfunction in patients with sleep apnea.

INTRODUCTION: Erectile dysfunction (ED) is frequent in patients with obstructive sleep apnea (OSA) and may act as a surrogate of endothelial dysfunction. Furthermore, impairments of vigilance and sustained attention are also commonly associated with OSA. AIM: The purpose of this study was to evaluate whether there is an association between ED and sustained attention deficits. METHODS: A prospective cross-sectional cohort of 401 male in-patients undergoing diagnostic polysomnography for suspected OSA and a 25-minute sustained attention test was analyzed. ED was assessed using the 15-item International Index of Erectile Function (IIEF-15) questionnaire. The Epworth Sleepiness Scale (ESS) served as a measure of daytime sleepiness. MAIN OUTCOME MEASURE: Severity of impaired erectile function (EF) assessed by the IIEF-15, core task parameters of the sustained attention test (i.e., CR: correct reactions; V-CR: variation of correct reactions, CE: commission errors, RT: reaction time; V-RT: variation of reaction times). RESULTS: Three hundred eighty-one consecutive patients presenting for in-lab polysomnography were included in the analysis. Impaired EF was diagnosed in 246 patients (65%). With increasing impairment of EF, patients scored significantly worse in all vigilance test parameters and demonstrated more severely diminished vigilance (normal EF: 11.9%, moderately impaired EF: 24.1%, and severely impaired EF: 34.9%). Multivariate regression analyses including established risk factors for ED, OSA, or sleepiness revealed a significant independent association between lower scores for EF and impairments on the following vigilance test variables: odds ratio (95% confidence interval) for V-CR: 0.52 (0.34-0.81), CE: 0.87 (0.80-0.95), and V-RT: 0.91 (0.87-0.96). The ESS was independently associated with both measures of performance instability: odds ratio for V-CR: 6.94 (2.97-16.23) and V-RT: 1.28 (1.14-1.44). CONCLUSIONS: In OSA patients, the severity of impaired EF was associated with impaired vigilance performance, independent of other known risk factors for ED or OSA and not mediated by sleepiness. Potentially, the findings suggest a direct relationship between vascular or endothelial dysfunction and impairments in both EF and neurobehavioral cognitive function.

Regensburg Insomnia Scale (RIS): a new short rating scale for the assessment of psychological symptoms and sleep in insomnia; study design: development and validation of a new short self-rating scale in a sample of 218 patients suffering from insomnia and 94 healthy controls.

BACKGROUND: The Regensburg Insomnia Scale (RIS) is a new self-rating scale to assess cognitive, emotional and behavioural aspects of psychophysiological insomnia (PI) with only ten items. A specific purpose of the new scale is the evaluation of the outcome of insomnia- specific cognitive behaviour therapy (CBT-I). METHODS: Internal consistency of the RIS has been validated in 218 patients with PI. For determining sensitivity and specificity, this sample has been compared to 94 healthy controls. Sensitivity to change and pre-post cross-validation with the Pittsburgh Sleep Quality Index (PSQI) has been tested in a separate sample of 38 patients with PI undergoing CBT-I. RESULTS: RIS distinguishes well between controls and patients with PI. Internal consistency was within a good range (Cronbach alpha = .890). RIS was sensitive for detecting improvements after CBT-I in sleep parameters and target symptoms such as sleep-related thinking. CONCLUSION: The RIS is a valid and feasible instrument for assessing psychological PI-symptoms and sleep parameters.

The assessment of vigilance: normative data on the Siesta sustained attention test.

OBJECTIVE: In several modern society duties individuals have to maintain their attention or vigilance over prolonged periods of time, even if the monitoring task is monotonous. The aim of our study was to obtain reference data on the 60-minute monotonous Siesta sustained attention test. METHODS: Normative data were gathered in an age-stratified sample of 234 healthy participants (118 men; 116 women) between the ages of 20 and 79 years. The impact of age, gender, time of day, and time on task during performance was analyzed. RESULTS: At least 20 participants from each age group and gender group were tested either in the morning or in the afternoon. The sample sizes were only smaller in the age group of 70 to 79 years. There was a notable age effect on all performance measures, with an increase in reaction times and false response rates from the youngest to the oldest group as well as a decrease in correct reactions with increasing age. Statistical analysis revealed no differences in speed and accuracy measures between men and women participants. There was no notable time-of-day effect but a clear impact of time-on-task speed and of correct reactions during the course of the test. The vigilance decrement had already occurred during the first half of the test. CONCLUSIONS: Our results provide a normative database of performance parameters for different age groups in healthy adult participants. As sustained attention is sensitive to sleep loss and nonrestorative sleep, our data can be used as a reference for performance-based assessment of daytime sleepiness in participants with hypersomnia.

Shortened night sleep impairs facial responsiveness to emotional stimuli.

Sleep deprivation deteriorates mood, impairs the recognition of facial expressions, and affects the ability to regulate emotions. The present study investigated the effect of partial sleep deprivation on facial responses to emotional stimuli. Thirty-three healthy undergraduates were tested twice: after a night with (i) 8h and (ii) 4h sleep. Self-reported sleepiness and sustained attention (Psychomotor Vigilance Task) were assessed. Emotional reactivity was measured with facial Electromyogram (EMG) while participants were asked to respond with either compatible or incompatible facial muscles to emotional stimuli in order to study whether partial sleep deprivation caused slower reactions mainly in response to incompatible stimuli (due to an additional effort to suppress the compatible reaction caused by decreased inhibitory control) or in response to both compatible and incompatible stimuli. Self-reported sleepiness and reaction times in a sustained attention task significantly increased after one night of partial sleep deprivation. Facial reactions to emotional stimuli were decelerated. No significant interaction between sleep restriction and compatibility of the muscle to the picture valence could be observed. Hence, volitional facial reactions in response to emotional stimuli were slower after one night of reduced sleep, but affective inhibitory control was not significantly impaired. However, slowed facial responding to emotional stimuli may affect social interaction after sleep restriction.

Insomnia symptoms influence CPAP compliance.

PURPOSE: The aim of this study is to determine parameters which influence 6-month compliance of continuous positive airway pressure therapy (CPAP) in patients with obstructive sleep apnea syndrome (OSAS). METHODS: This prospective study investigated 73 patients (24 females) with OSAS and medical indication for CPAP therapy: age 55.1 ± 11.5 years, body mass index (BMI) 30.8 ± 5.0 kg/m2, Apnea-Hypopnea Index (AHI) 39.2 ± 26.7/h, Oxygen Desaturation Index (ODI) 33.2 ± 25.4/h, minimum O(2) saturation 78.9 ± 7.6%. The influence of baseline parameters (demographic and polysomnographic data, sleeping medication intakes, BMI, psychometrics [Epworth Sleepiness Scale, Regensburg Insomnia Scale, Vigilance test and Beck Depression Inventory]) on 6-month compliance was evaluated with a correlation and a linear regression analysis. RESULTS: The baseline value of the Regensburg Insomnia Scale (RIS) predicts 6-month CPAP compliance (r = -0.376, R (2) = 0.14, p < 0.001), although no other baseline parameter correlates. Patients with a compliance of <4 h/night show higher RIS scores, i.e., more insomnia symptoms (17.6 ± 8.8) compared to those with ≥4 h/night (12.6 ± 6.9; p < 0.05). CONCLUSIONS: Insomnia symptoms prior to the beginning of CPAP treatment show a negative influence on CPAP compliance. Further studies should clarify, if a treatment of insomnia symptoms leads to a benefit in compliance.

The Pupillographic SleepinessTest in adults: effect of age, gender, and time of day on pupillometric variables.

OBJECTIVES: The Pupillographic Sleepiness Test (PST) measures the level of alertness based on spontaneous oscillations in pupillary size. Reference data are available for male and female adults within the age range 20-60 years. The aim of the present multicenter study was to extend the age range for reference data from 20 to 79 years. METHODS: A total of 239 healthy subjects, selected from three different centers (Berlin, Regensburg, and Vienna), were administered the PST. Data were analyzed with respect to possible effects of age, gender, and time of day on the pupillary unrest index (PUI) and the pupil diameter (PD). RESULTS: Reliable data were available in 85.8% of the entire study sample and in 82.4% of elderly subjects (60+ years). Age-related changes were identified for the PUI and PD. There was no effect of gender on pupillometric variables as revealed by univariate analysis. The PD was found to be smaller in the afternoon compared with the morning. However, if subjects aged 60+ years were excluded from the analyses, the age-related changes disappeared and a time-of-day effect regarding the PUI became apparent. CONCLUSIONS: PUI and PD were found to decrease with increasing age. In addition, the present data show that nonreliable PST data occur more frequently in the elderly probably because of dry eyes, inadequate testing conditions, and technical resolution limitations. Thus, the PST results obtained here from elderly subjects are limited and have to be interpreted with caution. Additional research on elderly specific assessment tools is needed.

Determinants of depressive symptoms in narcoleptic patients with and without cataplexy.

The present prospective study assesses depressive symptoms in narcoleptic patients with (NC+) and without (NC-) cataplexy (46 women, 40 men) and age- and sex- matched healthy controls. Seventy patients were under treatment with stimulants and/or anticataplectics. All subjects completed the Beck Depression Inventory (BDI), the Zung Self-Rating Depression Scale (SDS), the Global Impression of Severity of Depression (GSD), the Profile of Mood States (POMS) and Epworth Sleepiness Scale. Patients with narcolepsy were more depressed than controls (higher scores in BDI, GSD, SDS, and POMS [in the total score and in all subscale scores]); however, between the NC+ and NC- patient groups, no differences were found. Our study shows that the women and the patients using antidepressants and stimulants (combination) have a higher probability for depressive symptoms independent of the presence of cataplexy. The lack of difference between NC+ and NC- in the level of depression supports the assumption that the major psychosocial burden in narcolepsy is not necessarily associated with the presence of cataplexy.

Reduced intra-cortical inhibition after sleep deprivation: a transcranial magnetic stimulation study.

Sleep deprivation has multiple effects on brain function. It increases the risk for epileptic seizures both in healthy individuals and in patients with epilepsy. Furthermore it represents an effective antidepressive intervention with rapid onset. However, the mechanisms underlying these effects are still largely unknown. Transcranial magnetic stimulation (TMS) can be used as a non-invasive method for the measurement of motor cortex excitability. Here we used TMS for assessing sleep deprivation effects on cortical excitability in healthy individuals. Before and after 24 h of sleep deprivation, parameters of cortical excitability (resting motor threshold, short intracortical inhibition, intracortical facilitation, cortical silent period) were measured in a sample of 15 healthy volunteers (11 women, 4 men, aged between 21 and 30 years with a mean of 24.3±2.7 years). We detected a significant (p=0.042) reduction of short intracortical inhibition (SICI) after sleep deprivation. Motor threshold, intracortical facilitation and contralateral silent period remained unchanged. Our results confirm previous studies which have demonstrated changes of SICI after sleep deprivation. Our findings further suggest that the increased risk for epileptic seizures after sleep deprivation is mediated by a reduction of intracortical inhibition. Whether this mechanism is also involved in mediating the antidepressant effect of sleep deprivation has to be addressed by further studies in depressive patients.

[Sleep and pain: a bi-directional relation?]. / Schlaf und Schmerz: Ein wechselseitiger Zusammenhang?

OBJECTIVE: This review gives an overview about the consequences of sleep deprivation (SD) on pain perception and discusses the bi-directional relation between sleep and pain. METHODS: A MEDLINE research (16.7.2010) for the terms "sleep" AND "pain" AND ("sleep deprivation" OR "sleep loss" OR "sleep restriction" OR "sleep interruption") showed 177 hits. Only studies with control group or cross-over design that investigated sleep deprivation (total or partial form) as independent and pain as dependent variable were included. RESULTS: 7 studies fulfilled the inclusion criteria. SD leads in 5 of 6 studies to an increase of bodily complaints measured by self rating tests and a decrease of pain inhibition. 3 of 5 studies show a decrease of mechanical or thermal pain threshold after SD. CONCLUSIONS: Not only can pain lead to sleep disruption, but SD can also reduce pain threshold. Sleep and pain might be mutually related, by shared neurotransmitter pathways. A further explanation is an influence of SD on opioid protein synthesis and / or opioid receptors. So when chronic pain and sleep disorder coexist, both conditions should be treated.

The influence of age and sex on sleep latency in the MSLT-30--a normative study.

STUDY OBJECTIVES: The Multiple Sleep Latency Test-30 (MSLT-30) is a variation of the Multiple Sleep Latency Test with a fixed duration of 30 minutes for each of 5 test sessions. It requires less effort for reliable recording and is not susceptible to on-line scoring errors. The aim of the study was to provide normative data for the clinical use of the MSLT-30 and to evaluate the influence of age, sex, and other sociodemographic variables. DESIGN: An MSLT-30, along with measures of mood, objective, and subjective sleepiness was performed in a sample of healthy subjects in a balanced quota design. SETTING: Sleep laboratory in a sleep disorders center. PARTICIPANTS: One hundred subjects with no complaint of sleep disturbance or daytime sleepiness, 10 men and 10 women each from 5 age decades from 20 to 69 years. INTERVENTIONS: None. RESULTS: Mean latency to sleep stage 1 or any other sleep stage was 13.9 +/- 6.9 minutes. The SL-30 showed a clear quadratic association with age, with the shortest latencies in the middle age groups. No correlation was found between the mean latency to sleep stage 1 or any other sleep stage and sociodemographic variables or other measures of daytime sleepiness (Epworth Sleepiness Scale, vigilance test), mood scales, sleep quality (Pittsburgh Sleep Quality Index), and amount of prior sleep. CONCLUSIONS: Sleep latencies in normal subjects are age dependent in a quadratic fashion, with a minimum in middle-aged subjects. This reconciles the findings of a long mean sleep latency in the MSLT of adolescents and of an increase on the mean sleep latency with age in adults.