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The main study aim was to compare the validity of children sleep apnea data obtained from standard polysomnography (PSG) to a home sleep apnea test (HSAT) accompanied by an attending online video technician. Our study population was comprised of 100 children, 54 boys and 46 girls, ages 3–11 (average age 5.2, SD 1.2) assigned randomly either to in-lab full PSG or to a HSAT with real-time, online technical support to rule out obstructive sleep apnea (OSA). A t test comparison did not yield significant differences between data obtained from the in-lab PSG and HSAT with real-time, online, technical support for any of the following measures: Apnea–Hypopnea Index, Oxygen desaturation Index, baseline O2, or minimum O2 parameters. However, a significant difference was found for time in bed and total sleep time, which was significantly longer in the HAST. Online HSAT can provide a safe, convenient and a reliable way to perform sleep studies in young children for diagnosing OSA in their familiar home environment. [ABSTRACT FROM AUTHOR]

Purpose: Excessive daytime sleepiness (EDS) is a main symptom in patients with obstructive sleep apnea (OSA); however, patients with OSA have significant variability in their reported EDS which cannot be fully explained by the apnea-hypopnea index (AHI). The purpose of this study was to investigate gender differences regarding the sleep test variables contributing to excessive daytime sleepiness. Methods: Retrospective study of 578 men and 270 women with suspected OSA who underwent home overnight sleep test. We assessed the correlation between sleep test variables and EDS, using the Epworth Sleepiness Scale (ESS). Results: Among the group of men, correlation was found between ESS to BMI (r =.107, p =.010), AHI (r =.158, p <.001), number of apneas (r =.129, p =.002), number of hypopneas (r =.115, p =.006), number of blood oxygen desaturations (r =.145, p <.001), and percent of time the blood oxygen saturation was under 90% (r =.130, p =.002). However, among the group of women, no significant correlation was found between any of the sleep test parameters or BMI to ESS. Among the group of women, a negative correlation was found between age and EDS (r = −.208, p <.001). Conclusion: Men showed correlations between sleep test variables and EDS, while women did not show such correlations. The results suggest that men's sleepiness is more influenced by OSA and sleep variables compared to women. To our knowledge, this is the first study which shows difference between genders in the influence of sleep variables and OSA on EDS. [ABSTRACT FROM AUTHOR]

Current hypertension guidelines fail to provide a recommendation on when-to-treat, thus disregarding relevant circadian rhythms that regulate blood pressure (BP) level and 24 h patterning and medication pharmacokinetics and pharmacodynamics. The ideal purpose of ingestion-time (chronopharmacology, i.e. biological rhythm-dependent effects on the kinetics and dynamics of medications, and chronotherapy, i.e. the timing of pharmaceutical and other treatments to optimize efficacy and safety) trials should be to explore the potential impact of endogenous circadian rhythms on the effects of medications. Such investigations and outcome trials mandate adherence to the basic standards of human chronobiology research. In-depth review of the more than 150 human hypertension pharmacology and therapeutic trials published since 1974 that address the differential impact of upon-waking/morning versus at-bedtime/evening schedule of treatment reveals diverse protocols of sometimes suboptimal or defective design and conduct. Many have been "time-of-day," i.e. morning versus evening, rather than circadian-time-based, and some relied on wake-time office BP rather than around-the-clock ambulatory BP measurements (ABPM). Additionally, most past studies have been of too small sample size and thus statistically underpowered. As of yet, there has been no consensual agreement on the proper design, methods and conduct of such trials. This Position Statement recommends ingestion-time hypertension trials to follow minimum guidelines: (i) Recruitment of participants should be restricted to hypertensive individuals diagnosed according to ABPM diagnostic thresholds and of a comparable activity/sleep routine. (ii) Tested treatment-times should be selected according to internal biological time, expressed by the awakening and bed times of the sleep/wake cycle. (iii) ABPM should be the primary or sole method of BP assessment. (iv) The minimum-required features for analysis of the ABPM-determined 24 h BP pattern ought to be the asleep (not "nighttime") BP mean and sleep-time relative BP decline, calculated in reference to the activity/rest cycle per individual. (v) ABPM-obtained BP means should be derived by the so-called adjusted calculation procedure, not by inaccurate arithmetic averages. (vi) ABPM should be performed with validated and calibrated devices at least hourly throughout two or more consecutive 24 h periods (48 h in total) to achieve the highest reproducibility of mean wake-time, sleep-time and 48 h BP values plus the reliable classification of dipping status. (vii) Calculation of minimum required sample size in adherence with proper statistical methods must be provided. (viii) Hypertension chronopharmacology and chronotherapy trials should preferably be randomized double-blind, randomized open-label with blinded-endpoint, or crossover in design, the latter with sufficient washout period between tested treatment-time regimens. [ABSTRACT FROM AUTHOR]

The well-known Two-Process Model of Sleep Regulation describes the integration of the circadian rhythm of arousal and sleep – Process C, and the homeostatic pressure to sleep – Process S. Presently, the known biological markers for Process C are melatonin and core body temperature; whereas, for Process S, there is no biological marker except that of aspects of the electroencephalogram (EEG). Endozepines are a class of endogenous compounds that act like benzodiazepines (BZ), i.e., serving as ligands for the BZ binding sites on GABAA receptors. Not much is known about the role of endozepines, in particular non-peptide endozepines, in the sleep field except very few reports about high concentrations observed in endozepine stupor, a rare phenomenon of idiopathic recurring stupor. We focused on hypoxanthine and thromboxane A2, which are considered to have endozepine function. This study aimed to examine the effect of 24 h of acute sleep deprivation on blood levels of hypoxanthine and thromboxane A2 of healthy subjects without sleep problems or disorders. The results showed a significant decrease of both compounds in the morning after sleep deprivation in comparison to the unrestricted normal sleep condition, thereby suggesting that these endozepines are secreted regularly while asleep, and, thus, are necessary for the sleep process. This study is the first to suggest a connection between specific biological markers – endozepines and Process S – in the Two-Process Model of Sleep Regulation and, furthermore, it sheds light on the possible role of endozepines in sleepiness and fatigue. [ABSTRACT FROM AUTHOR]

The last several decades have been characterized by the widespread usage of digital devices, especially smartphones. At the same time, there have been reports of both decline in sleep duration and quality and male fertility decline. The aim of this study was to assess the relationship between evening exposure to the light-emitting screens of digital media devices and measures of both sleep and sperm quality. Semen samples were obtained from 116 men undergoing fertility evaluation for the following sperm variables: volume (mL), pH, sperm concentration (million/mL), motility percentage (progressive% + non-progressive motility%), and total sperm count. Exposure to the screens of electronic devices and sleep habits was obtained by means of a questionnaire. Smartphone and tablet usage in the evening and after bedtime was negatively correlated with sperm motility (−0.392; −0.369; p <.05), sperm progressive motility (−0.322; −0.299; p <.05), and sperm concentration (−0.169; p <.05), and positively correlated with the percentage of immotile sperm (0.382; 0.344; p <.05). In addition, sleep duration was positively correlated with sperm total and progressive motility (0.249; 0.233; p <.05) and negatively correlated with semen pH (−0.349; p <.05). A significant negative correlation was observed between subjective sleepiness and total and progressive motility (−0.264; p <.05) as well as total motile sperm number (−0.173; p <.05). The results of this study support a link between evening and post-bedtime exposure to light-emitting digital media screens and sperm quality. Further research is required to establish the proposed causative link and may lead to the future development of relevant therapeutic and lifestyle interventions. [ABSTRACT FROM AUTHOR]

Sleep deprivation (SD) is suggested to be associated with reduced thermo-regulatory functions. This study aimed to quantify the effect of partial (PSD) and total (TSD) 24 h SD using a standard heat tolerance test (HTT). Eleven participants underwent HTT after well-rested state, PSD and TSD. No significant physiological differences were found between the exposures but subjective discomfort was higher after TSD. Evening chronotypes' temperature during HTT was higher after TSD compared with PSD ( p = 0.017). After TSD, evening chronotypes compared to intermediate chronotypes' temperature was higher during the first hour of the HTT ( p < 0.05), suggesting that thermo-regulatory function during exercise in the heat is influenced by chronotype. [ABSTRACT FROM AUTHOR]

Objectives: We assessed the value of an ultrasound (US) examination in the diagnostic workup of patients with sleep-related breathing disorders by correlating US measurements with known parameters for the presence and severity of obstructive sleep apnea. Methods: Forty-one male patients who complained of snoring and/or daytime somnolence participated. The diagnostic protocol included history-taking, physical examination, polysoninography. and transcervical US examination of the tongue. The US results were compared with all of the other parameters. Results: The US imaging was reliable for demonstrating anatomic structures of the tongue base, discriminating between muscle, mucosa, and blood vessels. The lingual arteries were clearly visualized entering the tongue base at its lower lateral borders. There was a significant relationship between the severity of sleep-related breathing disorders (measured by polysoninography) and the width of the lower tongue base (measured as the distance between the lingual arteries). The distance between the lingual arteries also correlated with physical examination findings and patient complaints of daytime somnolence and the sensation of choking during the night. Conclusions: Tongue base width, measured by US. may influence the severity of obstructive sleep apnea. This is the first demonstration of the possible role of US examination, an inexpensive, noninvasive, and non-irradiating office procedure, in the diagnostic workup for sleep-related breathing disorders. [ABSTRACT FROM AUTHOR]

Context Medical school admissions traditionally rely heavily on cognitive variables, with non-cognitive measures assessed through interviews only. In recognition of the unsatisfactory reliability and validity of traditional interviews, medical schools are increasingly exploring alternative approaches that can provide improved measures of candidates’ personal and interpersonal qualities. Methods An innovative assessment centre (MOR [Hebrew acronym for ‘selection for medicine’]) was designed to measure candidates’ personal and interpersonal attributes. Three assessment tools were developed: behavioural stations, including encounters with simulated patients and group tasks; an autobiographical questionnaire, and a judgement and decision-making questionnaire. Candidates were evaluated by trained raters on four qualities: interpersonal communication; ability to handle stress; initiative and responsibility, and self-awareness. Results In the years 2004–05, the 588 medical school candidates with the highest cognitive scores were tested; this resulted in a change of approximately 20% in the cohort of accepted students compared with previous admission criteria. Internal consistency ranged from 0.80 to 0.88; inter-rater reliability ranged from 0.62 to 0.77 for the behavioural stations and from 0.72 to 0.95 for the questionnaires; test–retest score correlation was 0.7. The correlation between candidates’ MOR scores and cognitive scores approached zero, reflecting the value of MOR in the screening process. Feedback from participants indicated that MOR was perceived as fair and appropriate for medical school screening. Discussion MOR is a reliable tool for measuring non-cognitive attributes in medical school candidates. It has high content and face validity. Furthermore, its implementation conveys the importance of maintaining humanist characteristics in the medical profession to students and faculty staff. [ABSTRACT FROM AUTHOR]

Two behavioral phenomena characterize human motor memory consolidation: diminishing susceptibility to interference by a subsequent experience and the emergence of delayed, offline gains in performance. A recent model proposes that the sleep-independent reduction in interference is followed by the sleep-dependent expression of offline gains. Here, using the finger-opposition sequence–learning task, we show that an interference experienced at 2 h, but not 8 h, following the initial training prevented the expression of delayed gains at 24 h post-training. However, a 90-min nap, immediately post-training, markedly reduced the susceptibility to interference, with robust delayed gains expressed overnight, despite interference at 2 h post-training. With no interference, a nap resulted in much earlier expression of delayed gains, within 8 h post-training. These results suggest that the evolution of robustness to interference and the evolution of delayed gains can coincide immediately post-training and that both effects reflect sleep-sensitive processes. [ABSTRACT FROM AUTHOR]

Data Mining, or knowledge discovery, is the computer-assisted process of digging through and analyzing large quantity of data in order to extract meaningful knowledge. Data mining methods are used in many studies to identify phenomena quicker and better than human experts. One class of these methods was designed for dealing with time series data. However, when several channels of data are collected simultaneously, data mining algorithms encounter numerous difficulties since channels may be measured in different units, may be recorded at different sampling-rates, or may have completely different characteristics. Furthermore, as the size of these data increases, the amount of irrelevant data usually increases as well and the process becomes impractical. Hence, in such cases, the analyst must be capable of focusing on the informational parts while ignoring the noise data. These kinds of difficulties complicate the analysis of multi- channel data as compared to the analysis of single-channel data. This paper presents a useful technique for preprocessing multi channel data. Our technique supplies tools for coping with all the above-mentioned difficulties, and prepares the data for further analysis (using common algorithms, especially from the data mining field). The paper is divided as follows. After the introduction (Section I) we describe the state of the art (Section II), follows by the main section-methodology (Section III) which is divided to four steps (3.2-3.5). The results are described in a separate section (Section IV). Then, a discussion and conclusions of the proposed methodology are given in (Sections V and VI). Acknowledgements and the references follow. [ABSTRACT FROM AUTHOR]

This retrospective study describes the effects of long-term treatment with melatonin in 33 adolescents (age range, 10-18 years) with delayed sleep phase syndrome (DSPS). Patients were treated with oral melatonin, 3 to 5 mg/day for an average period of 6 months. During the treatment, sleep onset was advanced and sleep duration was longer. Treatment was also associated with a decrease in the proportion of patients reporting school difficulties. No adverse effects of melatonin were noted. This study indicates that long-term treatment with melatonin can be beneficial for adolescents with DSPS in terms of sleep-wake schedule and school performance. [ABSTRACT FROM AUTHOR]

Cognitive performance at night exhibits a substantial drop, typically before dawn. One of the means of dealing with this phenomenon, as well as with the accompanying sleepiness during sustained wakefulness, is the administration of stimulants. The most widely used and well‐documented stimulants are caffeine, amphetamines, and modafinil. Of these, amphetamines are the least recommended, as they may severely affect behavior. Caffeine and modafinil seem to produce relatively milder side effects and usually only at high doses. Previous comparison studies have revealed equal efficacy of both the stimulants in maintaining alertness and performance during sustained wakefulness. However, these studies used relatively high, and thus not completely safe, doses of these drugs (600 mg caffeine and 400 mg modafinil). Therefore, the aim of the present study was to assess the efficacy of a low and medically safe dose of caffeine (200 mg) and modafinil (200 mg) in maintaining cognitive performance during sustained wakefulness. A flight simulation task was chosen for the assessment of the stimulants in a counter‐balanced, within‐subject design under four different conditions: baseline (no drugs), placebo, caffeine (200 mg), and modafinil (200 mg). The equal effectiveness of both drugs in abolishing the nocturnal drop in cognitive performance, as well as of oral temperature and blood pressure, supported the use of low doses of caffeine and modafinil for the maintenance of alertness in healthy subjects during sustained wakefulness. [ABSTRACT FROM AUTHOR]

Objectives. Obstructive sleep apnea (OSA) is the main predisposing factor of excessive daytime sleepiness (EDS), and, therefore, increases the risk of road crashes. However, it is difficult to rely on medical intake for OSA or fatigue since drivers' symptoms reports are not reliable. On the other hand, direct measurement of EDS among large numbers of drivers carries serious practical drawbacks. Obstructive sleep apnea, in turn, is strongly related to obesity, and elevated body mass index (BMI) is considered one of the major risk factors for OSA. Thus, it could be postulated that BMI may carry predictive value for EDS proneness. Methods. The present study examined the interrelation between BMI, degree of OSA, as measured with Respiratory Distress Index (RDI), and the degree of EDS, as measured with the mean sleep onset latency in the Multiple Sleep Latency Test (MSLT) among obese (BMI = 32) professional drivers. The drivers went through polysomnography followed by the five sessions of MSLT in the next day. Results. In accordance with prior studies, we have found strong correlation between BMI and the degree of OSA on the one hand, and between the degree of OSA and EDS on the other hand. OSA was detected among 77.7% of the drivers, 47.1% were sleepy, 19% had severe sleepiness [mean sleep latency [MSL = 5 min.], 28.1% had moderate sleepiness [MSL = 10 min.]. None of the drivers complained about any sleep problem, including snoring, and all reported that they do not experience excessive daytime sleepiness. Thus, there was no correlation between their subjective report and objective findings. Conclusions. Obese drivers with BMI above 32 are highly prone to be sleepy during the day. Their subjective reports of OSA or fatigue symptoms are not reliable. Therefore it is highly recommended to screen them easily by weight and height measure for further sleep study and decision about their driving abilities. [ABSTRACT FROM AUTHOR]

A patient who developed an irregular sleep-wake pattern following prolactin-secreting pituitary microadenoma is described. The patient reported difficulties in sleep onset and awakening at the desired time, which caused major dysfunction in his daily life activities. Despite these difficulties, the sleep-related complaints of the patient remained unrecognized for as long as three yrs. Statistical analyses of the patient's rest-activity patterns revealed that the disruption of the sleep-wake circadian rhythm originated from a disharmony between ultradian (semicircadian) and circadian components. The circadian component displayed shorter than 24 h periodicity most of the time, but the semicircadian component fluctuated between longer and shorter than 12 h periods. Additionally, desynchrony in terms of period length was found in the tentative analyses of the rest-activity pattern, salivary melatonin, and oral temperature. While the salivary melatonin time series data could be characterized by a best-fit cosine curve of 24 h, the time series data of oral temperature was more compatible with 28 h best-fit curve. The rest-activity cycle during the simultaneous measurements, however, was best approximated by a best-fit curve of 21h. The dysregulation of circadian rhythms occurred concomitantly, but not beforehand, with the onset of pituitary disease, thus suggesting an association between the two phenomena. This association may have interesting implications to the modeling of the circadian time-keeping system. This case also highlights the need to raise the awareness to circadian rhythm sleep disorders and to consider disruptions of sleep-wake cycle in patients with pituitary adenoma. [ABSTRACT FROM AUTHOR]

Obstructive sleep apnea syndrome (OSAS) is associated with mild to severe cardiovascular risks. The most common standard treatment for OSAS, continuous positive airway pressure, was found to have beneficial effects on cardiovascular sequelae of OSAS. Additionally, commercial companies promote nonprescription treatments for OSAS. These products frequently lack scientific support for their efficacy and need further research. We report an objective test of magnetic therapy, one such product, in a patient with OSAS and cardiovascular comorbidities. Two nights of polysomnographic recording using the split-night protocol did not reveal any consistent differences in OSAS symptoms whether the patient slept with or without the magnetic equipment. It was concluded that magnetic treatment was unsuccessful in reducing OSAS symptoms in our patient and may even increase possible cardiovascular and stroke risks by preventing the patient from pursuing an adequate medical treatment, such as continuous positive airway pressure. [ABSTRACT FROM AUTHOR]

: BackgroundObstructive sleep apnea syndrome (OSAS) is associated with long-term cardiovascular morbidity. Little is known about these relations at early stages. We conducted a case-control study in which we analyzed the clinical characteristics of young adults who underwent a periodic health examination and were screened for, and eventually found to experience, OSAS.: MethodsWe identified 121 subjects newly diagnosed in a sleep study as having OSAS, and 229 matched control subjects in which screening for OSAS was negative. All had a medical interview, physical examination, and routine laboratory tests.: ResultsSubjects who had OSAS had a higher, body mass index (3-kg/m2 difference) and a higher diastolic blood pressure (4–mm Hg difference) value, without elevation in systolic blood pressure. There was no metabolic difference (lipids profile and fasting glucose levels) between groups.: ConclusionsDiastolic blood pressure is higher early in the course of OSAS. Long term follow-up may determine effects of prevention and early intervention in OSAS and associated hypertension. [Copyright &y& Elsevier]

A patient with Gilles de la Tourette syndrome treated with haloperidol, ingested once daily after awakening from sleep, exhibited an irregular sleep–wake pattern with a free-running component of approximately 48 h. Transfer to risperidone, ingested once daily after awakening from sleep, was beneficial resulting in a sleep–wake cycle more synchronized at the appropriate phase to the external zeitgebers, and fewer nocturnal disturbances. The circadian sleep–wake schedule was fully synchronized when the patient had been subsequently treated with melatonin at 21:00h, before intended nocturnal sleep, in addition to risperidone in the morning. Restoration of the sleep–wake circadian pattern was accompanied by the patient's subjective report of significant improvement in his quality of life, social interactions, and occupational status. This observation suggests that circadian rhythm sleep disorders can be related to the typical neuroleptic haloperidol and restored by the atypical neuroleptic risperidone. Similar findings reported in patients suffering from other disorders support the hypothesis that the described disruption of the sleep–wake schedule is medication rather than illness-related. Therefore, it is very important to realize that circadian rhythm sleep disorders may be a side effect of neuroleptics. [ABSTRACT FROM AUTHOR]

We evaluated 32 nonmedicated male adolescents diagnosed with attention-deficit/hyperactivity disorder (ADHD) in childhood, 35 male adolescents similarly diagnosed who were receiving methylphenidate (MPH), and 77 control boys. Both ADHD groups completed self-report questionnaires assessing sleep disturbances; weekday and holiday sleep duration; and symptoms of ADHD, anxiety, and depression. Parents and teachers rated the severity of the participants' ADHD. The control group completed self-report questionnaires assessing sleep disturbances. We found that nonmedicated participants and controls did not differ in the severity of sleep disturbance. In contrast, the medicated participants demonstrated a significantly greater severity of sleep disturbance compared with the nonmedicated participants and reported elevated levels of symptoms of ADHD, anxiety, and depression. Specific analyses showed that depressive symptoms contributed significantly to the degree of sleep disturbance when controlling for ADHD diagnosis and MPH treatment. These findings suggest that among adolescents with ADHD symptoms, the severity of symptoms of depression may contribute to the degree of sleep disturbance in addition to the effect of their primary disorder and MPH treatment. [ABSTRACT FROM AUTHOR]

Certain sleep-wake schedule disorders (SWSDs) cannot be successfully managed clinically using conventional methods of sleep therapy. We describe two cases of SWSD, the first following head trauma and the second originating during childhood, that had been misdiagnosed by physicians for many years. After conventional treatment for SWSD with light therapy and melatonin failed to bring about substantial improvement, it was determined that they were suffering from an incurable disability. Hence, we propose new medical terminology for such cases—SWSD disability. SWSD disability is an untreatable pathology of the circadian time structure. Patients suffering from SWSD disability should be encouraged to accept the fact that they suffer from a permanent disability, and that their quality of life can only be improved if they are willing to undergo rehabilitation. It is imperative that physicians recognize the medical condition of SWSD disability in their patients and bring it to the notice of the public institutions responsible for vocational and social rehabilitation. (Chronobiology International, 18(6), 1019–1027, 2001) [ABSTRACT FROM AUTHOR]

Objective.—A controlled objective and subjective evaluation of sleep in a consecutive series of persons who had had a whiplash injury, shortly following the injury and 3 to 5 months later. Methods.—In whiplash-injured subjects and healthy controls, sleep characteristics were monitored objectively throughout the night by means of an actigraph. The following morning, participants in both groups filled out a prestructured “sleep log” that conveyed their subjective impressions as to how they had slept. The correlation between objectively measured sleep characteristics and the symptoms and physical findings, respectively, resulting from whiplash injury were also examined. Results.—Actigraphic monitoring did not reveal a significant group difference between whiplash-injured subjects and controls with respect to any of the sleep characteristics recorded. In self-maintained “sleep logs,” however, the whiplash-injured subjects reported a significantly prolonged sleep latency and significantly impaired sleep quality compared with controls (P<.001 and P<.04, respectively). In whiplash-injured subjects, the number of arousals was positively correlated with the number of symptoms and with the number of physical signs of whiplash injury (P<.01 and P<.001, respectively). Sleep efficiency was inversely correlated with the number of injury-related findings on physical examination (P<.009). Conclusion.—Sleep, as monitored by actigraph in whiplash-injured subjects, was not adversely affected by whiplash injury. The subjective impressions of the subjects, as recorded in “sleep logs,” suggest the opposite conclusion. A significant correlation exists between certain symptoms and signs of whiplash injury and abnormalities in given sleep characteristics as detected by actigraph. [ABSTRACT FROM AUTHOR]

Abstract This study analysed women's dreams reported during first pregnancy, a subject matter located at the crossroads of the psychology of dreams and the psychology of pregnancy. In the comparison of dreams reported by first-time pregnant women, to those reported by controls, we hypothesized that pregnant women's dreams would: (i) include more pregnancy-related content; (ii) display a higher degree of anxiety; and (iii) rate higher on a primary-process thinking (PPT) scale. As predicted, it was found that pregnancy-related contents significantly occupied pregnant women's dreams, a fact that might be attributed to an attempt to process and master the experience. Contrary to our expectations, it was found that anxiety and PPT were not significantly higher among pregnant women. An attempt to account for these findings raised methodological, as well as theoretical issues, consequently leading to a re-examination of the original hypotheses. Thus, it was claimed that the linkage of pregnancy to increased anxiety and PPT is grossly unbalanced. [ABSTRACT FROM AUTHOR]

PURPOSE. To determine whether parameters calculated from pupillary activity can identify subjects with sleep deprivation, and whether the objective values correlate with a subjective feeling of fatigue. METHODS. pupil size in the dark was recorded continuously for 10 minutes in 12 healthy volunteers using an infrared video camera. Two recordings were made for each subject: after a full night's sleep, and after 24 hours of sleep deprivation. Several parameters calculated from pupil size and activity were analyzed and compared with a subjective rating of the state of alertness provided by the participants in each test. RESULTS. All pupillary parameters differed significantly between alertness and fatigue (p = 0.0076–0.0186). Changes in one of the parameters – average pupillary diameter – correlated with changes in the subjective level of sleepiness (r = -0.51, p = 0.028). Although the values of most parameters differed among subjects, an absolute value of more than 25 in one parameter, cumulative pupillary variability ratio, was always associated with sleep deprivation. CONCLUSION. On-line analysis of the pupillogram using the suggested parameters can be performed easily to produce a real-time assessment of an individual's state of alertness or fatigue that correlates with his/her subjective assessment of this state. [ABSTRACT FROM AUTHOR]