In order to study both the prevalence of Primary Sleep Disorders (PSD) and sleepiness, and their association to the Chronic Fatigue Syndrome (CFS), 46 unselected outpatients (34 women, mean age 36.5) were examined clinically and underwent two nights of all-night polysomnography and multiple sleep latency tests (MSLT). Forty-six percent presented with a Sleep Apnea/Hypopnea Syndrome Index (AHI>=5), 5% with a Periodic Limb Movements syndrome. No subject received a diagnosis of Narcolepsy or Idiopathic Hypersomnia. Thirty percent showed the presence of objective sleepiness as measured by MSLT<10 minutes. Objective and subjective measures of sleepiness were not associated with CFS, nor with the double diagnosis of CFS and a PSD. The presence of PSD or sleepiness was not associated with any of the clinical scales that were used to measure anxiety, depression, somatisation, physical or mental fatigue, or functional status impairment. Fifty-four percent of CFS patients had no PSD, and 69% no sleepiness. These patients could not be distinguished clinically from patients having a PSD or from those with sleepiness. Therefore, it is unlikely that CFS is simply a somatic expression of any PSD observed in our sample or of sleepiness per se.

Sleep Research Online

The "immediate-onset"-acting hypnotics (1-2 h after oral administration) (e.g., benzodiazepines) serve as the leading approach and great progress has been made in this century. They are exogenous from artificial synthesis and mainly fit for short-term insomnia. The "gradual-onset"-acting hypnotics (3-5 d after oral administration) are mild and gradually effective, but are very safe and without noticeable side or adverse effects. They are endogenous or endogenous-mimetic from natural isolation. It may serve as a more natural approach for the treatment of chronic or long-term insomnia, which is mainly gradually developed. This approach is especially useful in treating elderly people, whose numbers are rapidly increasing worldwide, especially in the next century. Sleep-Aid Tea (SAT) is a naturally processed Tea consisting of endogenous or endogenous-mimetic sleep-inducing substances isolated from specific natural and edible fruits and plants well known for the treatment of insomnia, e.g., Compendium of Materia Medica (Li, 1596) associated with modern knowledge and isolation technology (Liu, 1990, 1993). SAT is especially fit for the treatment of insomnia in aged people because it is mild, "gradual-onset"-acting (3-5 d after oral administration), natural, safe and without side effects.

Sleep Research Online

The time-courses of power in the different frequency bands (1-40 Hz) within the non-rapid-eye-movement (NREM) episode of the human sleep electroencephalogram have provided for many years a fascinating window into the sleep process. Here our analysis of the slow-wave band (1-4 Hz) reveals a hitherto unrecognized very slow oscillation of power with mean period ~15 minutes, an instability that appears to be an integral characteristic of the early NREM episode. The neuronal transition probability (NTP) model has already given a mechanism explaining how power in the spindle band peaks consistently before that of slow wave activity. Here we show that an extension of the model, with the hypothesis of a population of sleep neurons alternating between two steady probability states, can simulate the very slow oscillation. In doing so it gives not only the time course of power in the slow wave band, but also the simultaneous time-courses in the spindle and in the fast frequency bands. Animal data suggest that a brainstem neuronal population, toggled by an external switching source, generates these time-courses and dictates them to the thalamus and thence to the cortex. The discovery of the very slow oscillation and the success of the NTP model in interpreting the overall NREM structure may have important implications for both clinical and fundamental sleep research.

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Isolated Sleep Paralysis (SP) occurs at least once in a lifetime in 40-50% of normal subjects, while as a chronic complaint it is an uncommon and scarcely known disorder. A series of messages written by subjects who experienced at least one episode of SP, containing more or less detailed descriptions of this disorder, were collected from the Sleep Web site of the University of California in Los Angeles between January 1996 and July 1998. Two hundred and sixty-four messages fulfilling the International Classification of Sleep Disorders (ICSD) (Thorpy, 1990) minimal criteria for SP were analyzed. A wide spectrum of severity was evident, with a frequency of episodes ranging from one in a lifetime to almost every night, and a variety of emotional and hallucinatory experiences associated with SP episodes were reported. Clinical similarities between the recurrent form of isolated SP and channelopathies (in particular, periodic paralyses) are discussed. An activation of limbic system structures is suggested in order to explain some of the most common subjective experiences associated with SP.

Sleep Research Online

The aim of this experiment was to compare the characteristics of mental activity during REM and Slow Wave Sleep (SWS). Forty dream reports and their mnemonic associations were collected from twenty subjects. The reports were analyzed for structure (number of temporal units, number of report multi-units, and narrative continuity), awareness (reality testing, subjective time), and content (self, setting, laboratory references, number of non-self characters, implausibility, body feelings, number and intensity of emotions, vividness). Associations were classified as episodic and semantic memories. Results showed that REM reports were significantly longer than SWS reports. Minor content SWS-REM differences were also detected, which were more quantitative than qualitative. The collected observations might support the tentative hypothesis that dreaming is a continuous process, which is not unique to REM sleep. Different levels of engagement of the cognitive system are responsible for the SWS-REM differences that were detected.

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The effect of a single nucleotide polymorphism, a glutamine to arginine amino acid substitution in the human Timeless gene (Q831R, A2634G), on diurnal preferences was studied in a random sample of normal volunteers enrolled in a population-based epidemiology study of the natural history of sleep disorders. We genotyped 528 subjects for this single nucleotide polymorphism and determined morningness-eveningness tendencies using the Horne-Ostberg questionnaire. Our results indicate that Q831R Timeless has no influence on morningness-
eveningness tendencies in humans.

Sleep Research Online

In the transition from NREM to REM sleep, as in other instances of brain activation, a marked increase in cerebral blood flow and glucose uptake is observed, together with a lesser increase in O₂ uptake. Brain activation also entails an increase in capillary PO₂ and lactate production. The hypothesis of saturation of the oxidative machinery was advanced to explain anaerobic glycolysis and lactate production in the presence of high PO₂, but data are available that cannot be explained by this hypothesis: hypoxic spots exist in the brain, augmenting in arterial hypoxia and disappearing in arterial hyperoxia, while tissue [H⁺] lowers as arterial PO₂ increases beyond 100 mmHg. Additional hypotheses are thus required. We suggest that O₂ diffusion limitation exists in the brain: microregions lying at mid-distance between capillaries may become hypoxic and partly resort to anaerobic glycolysis. These microregions are thought to enlarge with increasing metabolic rate or arterial hypoxia and give rise to vasodilatatory signals regulating local blood flow. REM sleep time is strongly reduced by hypoxic and increased by hyperoxic atmosphere, in accordance with the existence of an O₂ diffusion limitation. Any pathological decrease in arterial PO₂ and/or O₂ delivery creates a specific risk in REM sleep.

Sleep Research Online