Jürgen Zulley

The dependence of onset and duration of sleep on the circadian rhythm of rectal temperature

The sleep-wake cycle and the circadian rhythm of rectal temperature were recorded in subjects who lived singly in an isolation unit. In 10 subjects, the freerunning rhythms remained internally synchronized, 10 other subjects showed internal desynchronization. Times of onset and end of bedrest (“sleep”) were determined in each cycle and referred to the phase of the temperature rhythm. In the synchronized subjects, onset of sleep occurred, on the average, 1.34 h before the minimum of temperature, and end of sleep 6.94 h thereafter, with narrow distributions. The desynchronized subjects had a broad bimodal distribution of sleep onsets (peaks 6.3 and 1.3 h before the minimum); the duration of sleep varied between more than 15 h when sleep began about 10 h before the temperature minimum, and less than 4 h when sleep began several hours after the minimum. The dependence of sleep duration on body temperature is interpreted as a continuing action of the coupling forces between the two rhythms after mutual synchronization is lost.

Prevalence and Patterns of Problematic Sleep Among Older Adolescents

OBJECTIVE Despite many constraints on time schedules among teenagers, epidemiological data on sleep complaints in adolescence remain limited and are nonexistent for sleep disorders. This study provides additional data on sleep habits and DSM-IV sleep disorders in late adolescence. METHOD A representative sample of 1,125 adolescents aged 15 to 18 years was interviewed by telephone using the Sleep-EVAL system. These adolescents came from 4 European countries: France, Great Britain, Germany, and Italy. Information was collected about sociodemographic characteristics, sleep/wake schedule, sleep habits, and sleep disorders and was compared with information from 2,169 young adults (19-24 years of age). RESULTS Compared with young adults, adolescents presented with a distinct sleep/wake schedule: they went to sleep earlier, they woke up later, and they slept longer than young adults did. On weekends and days off, they also slept more than young adults did. However, the prevalence rates of sleep symptoms and sleep disorders were comparable in both groups. Approximately 25% reported insomnia symptoms and approximately 4% had a DSM-IV insomnia disorder. Fewer than 0.5% had a circadian rhythm disorder. CONCLUSIONS Prevalence of insomnia disorders is lower in the adolescent population than in middle-aged or elderly adults. However, a rate of 4% in this young population is important given their young age and the consequences for daytime functioning.

Prevalence of narcolepsy symptomatology and diagnosis in the European general population

Objective: To determine the prevalence of narcolepsy in the general population of five European countries (target population 205,890,882 inhabitants). Methods: Overall, 18,980 randomly selected subjects were interviewed (participation rate 80.4%). These subjects were representative of the general population of the UK, Germany, Italy, Portugal, and Spain. They were interviewed by telephone using the Sleep-EVAL expert system, which provided narcolepsy diagnosis according to the International Classification of Sleep Disorders (ICSD). Results: Excessive daytime sleepiness was reported by 15% of the sample, with a higher prevalence in the UK and Germany. Napping two times or more in the same day was reported by 1.6% of the sample, with a significantly higher rate in Germany. Cataplexy (episodes of loss of muscle function related to a strong emotion), a cardinal symptom of narcolepsy, was found in 1.6% of the sample. An ICSD narcolepsy diagnosis was found in 0.047% of the sample: The narcolepsy was severe for 0.026% of the sample and moderate in 0.021%. Conclusion: This is the first epidemiologic study that estimates the prevalence of narcolepsy in the general population of these five European countries. The disorder affects 47 individuals/100,000 inhabitants.

How age and daytime activities are related to insomnia in the general population: Consequences for older people

OBJECTIVES: To determine the role of activity status and social life satisfaction on the report of insomnia symptoms and sleeping habits.

Prevalence and pathologic associations of sleep paralysis in the general population

Background: Previous epidemiologic data on sleep paralysis (SP) came from small specific samples. The true prevalence and associated factors of SP in the general population remain unknown. Method:— A representative sample of the noninstitutionalized general population of Germany and Italy age ≥15 years (n = 8,085) was surveyed by telephone using the Sleep-EVAL questionnaire and the Sleep Questionnaire of Alertness and Wakefulness. Results: Overall, 6.2% (5.7 to 6.7%) of the sample (n = 494) had experienced at least one SP episode in their lifetime. At the time of the interview, severe SP (at least one episode per week) occurred in 0.8% of the sample, moderate SP (at least one episode per month) in 1.4%, and mild SP (less than one episode per month) in 4.0%. Significant predictive variables of SP were anxiolytic medication, automatic behavior, bipolar disorders, physical disease, hypnopompic hallucinations, nonrestorative sleep, and nocturnal leg cramps. Conclusions: SP is less common in the general population than was previously reported. This study indicates that the disorder is often associated with a mental disorder. Users of anxiolytic medication were nearly five times as likely to report SP, even after we controlled for possible effects of mental and sleep disorders.

The alteration of human sleep and circadian rhythms during spaceflight

Numerous anecdotes in the past suggest the concept that sleep disturbances in astronauts occur more frequently during spaceflight than on ground. Such disturbances may be caused in part by exogenous factors, but also an altered physiological state under microgravity may add to reducing sleep quality in a spacecraft. The present investigation aims at a better understanding of possible sleep disturbances under microgravity. For the first time, experiments were conducted in which sleep and circadian regulation could be simultaneously assessed in space. Four astronauts took part in this study aboard the Russian MIR station. Sleep was recorded polygraphically on tape together with body temperature. For a comparison, the same parameters were measured during baseline periods preceding the flights. The circadian phase of body temperature was found to be delayed by about 2 h in space compared with baseline data. A free‐run was not observed during the first 30 d in space. Sleep was shorter and more disturbed than on earth. In addition, the structure of sleep was significantly altered. In space, the latency to the first REM episode was shorter, and slow‐wave sleep was redistributed from the first to the second sleep cycle. Several mechanisms may be responsible for these alterations in sleep regulation and circadian phase. Most likely, altered circadian zeitgebers on MIR and a deficiency in the process S of Borbélys sleep model cause the observed findings. The change in process S may be related to changes in physical activity as a result of weightlessness.

Is sleep-disordered breathing an independent risk factor for hypertension in the general population (13,057 subjects)?

UNLABELLED OBJECTIVES Sleep-disordered breathing has been hypothesized to have a close relationship with hypertension but previous studies have reported mixed results. This is an important health issue that requires further clarification because of the potential impact on the prevention and control of hypertension. METHODS The relationship between hypertension and three forms of sleep-disordered breathing (chronic snoring, breathing pauses and obstructive sleep apnea syndrome (OSAS)) was assessed using representative samples of the non-institutionalized population of the UK, Germany and Italy (159 million inhabitants). The samples were comprised of 13,057 individuals aged 15-100 years who were interviewed about their sleeping habits and their sleep symptoms over the telephone using the Sleep-EVAL system. RESULTS OSAS was found in 1.9% (95% CI: 1.2% to 2.3%) of the UK sample, 1.8% (95% CI: 1.4% to 2.2%) of the German sample and 1.1% (95% CI: 0.8% to 1.4%) of the Italian sample. OSAS was an independent risk factor (odds ratio (OR): 9.7) for hypertension after controlling for possible confounding effects of age, gender, obesity, smoking, alcohol consumption, life stress, and, heart and renal disease. CONCLUSIONS Results from three of the most populated countries in Western Europe indicate that OSAS is an independent risk factor for hypertension. Snoring and breathing pauses during sleep appeared to be non-significant predictive factors.

The place of confusional arousals in sleep and mental disorders - Findings in a general population sample of 13,057 subjects

Confusional arousals, or sleep drunkenness, occur upon awakening and remain unstudied in the general population. We selected a representative sample from the United Kingdom, Germany, and Italy (N = 13,057) and conducted telephone interviews. Confusional arousals were reported by 2.9% of the sample: 1% (95% confidence interval: .8 to 1.2%) of the sample also presented with memory deficits (53.9%), disorientation in time and/or space (71%), or slow mentation and speech (54.4%), and 1.9% (1.7% to 2.1%) reported confusional arousals without associated features. Younger subjects (< 35 years) and shift or night workers were at higher risk of reporting confusional arousals. These arousals were strongly associated with the presence of a mental disorder with odds ratios ranging from 2.4 to 13.5. Bipolar and anxiety disorders were the most frequently associated mental disorders. Furthermore, subjects with Obstructive Sleep Apnea Syndrome (OSAS), hypnagogic or hypnopompic hallucinations, violent or injurious behaviors, insomnia, and hypersomnia are more likely to suffer from confusional arousals. Confusional arousals appears to occur quite frequently in the general population, affecting mostly younger subjects regardless of their gender. Physicians should be aware of the frequent associations between confusional arousals, mental disorders, and OSAS. Furthermore, the high occurrence of confusional arousals in shift or night workers may increase the likelihood of inappropriate response by employees sleeping at work.

Initial REM sleep suppression by clomipramine: A prognostic tool for treatment response in patients with a major depressive disorder

Kupfer et al. (1976, 1981) demonstrated, in a sample of 82 depressed patients, that the amount of rapid eye movement (REM) sleep suppression during the initial 2 nights of treatment with amitriptyline correlated positively with clinical response. Gillin et al. (1978) were able to replicate this finding in six depressed patients. From these results, it may be speculated that polysomnographic measurement of REM sleep in patients during the initial nights of treatment with ~tidepressive drugs may offer the possibility of improving drug therapy. Whereas in clinical practice the response to antidepressive medication can only be evaluated after at least 10-14 days of medication (Woggon 1983), the predictive value of REM sleep changes may allow us to avoid unsuccessful treatment early in the course of therapy. The above-cited studies raise the question of whether or not it is possible to establish the threshold of initial REM sleep suppression necessary for successful drug therapy, thereby providing a substantial differentiai-therapeutic tool that could influence the choice of drug or dosage. The aim of the present

EEG sleep and the cholinergic REM induction test in anorexic and bulimic patients

The electroencephalographic (EEG) sleep of 20 anorexic patients, 10 bulimic patients, and 10 age-matched healthy controls was studied. In addition, six anorexic patients and six bulimic patients had a cholinergic rapid eye movement (REM) sleep induction test (RIT) performed with the cholinergic agent RS 86. The three samples showed no major differences in sleep patterns. The same held true when attention was focused on patients who additionally met DSM-III criteria for major depression. The RIT results were similar in the patients with eating disorders and in controls, but differed from those reported in depressives. Therefore, the present study found no hints of depression-like sleep patterns in patients with eating disorders.