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Biomedical subjects

M Inugami

Publications and source records attributed to M Inugami.

14 recordsLinked to original sources
PubMed2001

Intrinsic dreams are not produced without REM sleep mechanisms: evidence through elicitation of sleep onset REM periods.

The hypothesis that there is a strict relationship between dreams and a specific rapid eye movement (REM) sleep mechanism is controversial. Many researchers have recently denied this relationship, yet none of their studies have simultaneously controlled both sleep length and depth prior to non-REM (NREM) and REM sleep awakenings, due to the natural rigid order of the NREM--REM sleep cycle. The failure to control sleep length and depth prior to arousal has confounded interpretations of the REM-dreams relationship. We have hypothesised that different physiological mechanisms underlie dreaming during REM and NREM sleep, based on recent findings concerning the specificity of REM sleep for cognitive function. Using the Sleep Interruption Technique, we elicited sleep onset REM periods (SOREMP) from 13 normal subjects to collect SOREMP and sleep onset NREM (NREMP) dreams without the confounds described above. Regression analyses showed that SOREMP dream occurrences were significantly related to the amount of REM sleep, while NREMP dream occurrences were related to arousals from NREM sleep. Dream properties evaluated using the Dream Property Scale showed qualitative differences between SOREMP and NREMP dream reports. These results support our hypothesis and we have concluded that although 'dreaming' may occur during both REM and NREM periods as previous researchers have suggested, the dreams obtained from these distinct periods differ significantly in their quantitative and qualitative aspects and are likely to be produced by different mechanisms.

Adolescent↗
PubMed2000

Sleep onset REM period appearance rate is affected by REM propensity in circadian rhythm in normal nocturnal sleep.

OBJECTIVE: REM latency is usually 60-120 min, but under certain conditions, its latency may be less than 25 min, in which it is known as sleep onset REM period (SOREMP). In order to identify the factors responsible for the appearance of SOREMP, we used the nocturnal sleep interruption method to investigate whether REM propensity in normal nocturnal sleep, (i.e. circadian variations in REM sleep related to body temperature rhythm), could affect the rate of SOREMP appearance (SOREMP%). MATERIALS AND METHODS: After two adaptation and one baseline nights, we interrupted the nocturnal sleep, either in the second or the fourth cycle (early and late conditions, respectively) of 16 subjects and compared SOREMP% at the second sleep onset between these conditions by chi(2) test. Rectal temperature was measured. RESULTS: SOREMP% was found to be 58.1% in the early condition and 87.5% in the late condition - a significant difference. Body temperature dropped at the second sleep onset in both conditions but the drops did not differ significantly. CONCLUSION: We concluded that SOREMP% was affected by circadian variations in REM propensity but SOREMP% and body temperature drop did not show a linear relationship. Further studies to discriminate the influence of circadian rhythm factors and slow wave sleep on SOREMP% are called for.

Adolescent↗
PubMed1999

Classification of the sleeping pattern of normal adults.

A questionnaire concerning their sleep-related lifestyle and mental health was mailed to people aged in their twenties to fifties living in the Fukushima (North East), Tokyo (Central, Metropolitan) and Okayama (West) areas of Japan. We classified the sleeping pattern of 3642 people (1702 men, 1940 women; mean age 41.3+/-10.67) by multivariational analyses (factor analysis and cluster analysis). They were classified into six groups and defined as 'poor sleeper group' (30.0%), 'good sleeper group' (28.3%), 'long sleeper group' (8.2%), 'short sleeper group' (18.5%), 'irregular sleeper group' (11.3%), and 'Delayed Sleep Phase Syndrome group' (3.7%) based on their characteristics of the factor pattern.

Adult↗
PubMed1998

Core temperature pattern and self-rated lifestyle.

We investigated the relationship between a subject's self-rated lifestyle and their pattern of nocturnal rectal temperature. Fifty-five students participated in the study. Among several significant findings, irregularity and eveningness component of lifestyle (irregular and delayed sleep phase) showed a significant negative correlation with temperature at the morning rising time. Examination of the nocturnal temperature pattern revealed that rectal temperature stayed at its lowest level in the early morning hours in the subjects with irregular and eveningness-like lifestyles.

Adult↗
PubMed1994

Laboratory-documented hallucination during sleep-onset REM period in a normal subject.

During an experiment on nocturnal sleep interruption, we observed a unique case of hallucination without sleep paralysis during the sleep-onset REM period in a normal individual. We documented the polysomnogram recorded during this hallucination. The polysomnogram showed a mixed pattern of Stages REM and W, with muscle-tone inhibition, rapid eye movements (REMs), slow eye movements (SEMs), and abundant alpha EEG trains. The blocking of alpha EEG trains by REMs appeared to reflect visual processing similar to that which occurs during waking. This hallucination was distinct from ordinary sleep-onset mentation in that it included strong emotional components and in that the subject simultaneously experienced both hallucinatory mentation and reality contact. This hallucination may resemble sleep paralysis with regard to its physiological and psychological background, and the discrimination of these two phenomena may depend on the subject's own awareness of muscle-tone inhibition.

Adult↗
PubMed1993

Effects of sleep interruption on body temperature in human subjects.

We interrupted the nocturnal sleep of human subjects for an hour and investigated the effect on body temperature (BT). The interruption elicited sleep onset rapid eye movement period (SOREMP). We compared the BT patterns obtained during nights with SOREMP at the second sleep onset (SOREMP nights) and those obtained during nights without SOREMPs (non-SOREMP nights) with those obtained during baseline nights. BT decreased markedly after sleep interruption on both SOREMP and non-SOREMP nights. It remained lower for 2 hours after the second sleep onset when compared with the corresponding period on the baseline nights. Consequently, the minimum BT was lower and the timing of the minimum was advanced when compared with baseline. The fall of BT after sleep interruption was not accompanied by any increase in slow wave sleep (SWS, stage 3 + 4) when compared with the baseline nights. Thus, we suggest that no direct relationship exists between the decrease of BT and the amount of SWS. On SOREMP nights, the fall of BT from lights-out to the second sleep onset was larger than on non-SOREMP nights. This lower body temperature at the second sleep onset may reflect the physiological background necessary for the appearance of SOREMPs.

Adult↗
PubMed1992

Isolated sleep paralysis elicited by sleep interruption.

We elicited isolated sleep paralysis (ISP) from normal subjects by a nocturnal sleep interruption schedule. On four experimental nights, 16 subjects had their sleep interrupted for 60 minutes by forced awakening at the time when 40 minutes of nonrapid eye movement (NREM) sleep had elapsed from the termination of rapid eye movement (REM) sleep in the first or third sleep cycle. This schedule produced a sleep onset REM period (SOREMP) after the interruption at a high rate of 71.9%. We succeeded in eliciting six episodes of ISP in the sleep interruptions performed (9.4%). All episodes of ISP except one occurred from SOREMP, indicating a close correlation between ISP and SOREMP. We recorded verbal reports about ISP experiences and recorded the polysomnogram (PSG) during ISP. All of the subjects with ISP experienced inability to move and were simultaneously aware of lying in the laboratory. All but one reported auditory/visual hallucinations and unpleasant emotions. PSG recordings during ISP were characterized by a REM/W stage dissociated state, i.e. abundant alpha electroencephalographs and persistence of muscle atonia shown by the tonic electromyogram. Judging from the PSG recordings, ISP differs from other dissociated states such as lucid dreaming, nocturnal panic attacks and REM sleep behavior disorders. We compare some of the sleep variables between ISP and non-ISP nights. We also discuss the similarities and differences between ISP and sleep paralysis in narcolepsy.

Adolescent↗
PubMed1989

Effects of sleep interruption on REM-NREM cycle in nocturnal human sleep.

Forty-four normal male students, aged 18-23 years were studied. After adaptation and baseline night (BN), 3 or 4 consecutive nights were interrupted by a forced awakening (10-90 min) once a night (ENs). Subjects (Ss) were awakened after they had slept for the first sleep cycle plus 20 min of NREM sleep in the 2nd cycle. The REM latencies following return to sleep showed a bimodal distribution separated by 25-30 min. The ENs were divided into 2 clusters: SOREMP (sleep onset REM period) and non-SOREMP nights. After interruption, the 2nd and the 3rd REM durations increased on non-SOREMP nights compared to SOREMP nights. We plotted, separately for SOREMP and non-SOREMP nights, the fluctuation of REM episode probability (FRP) at successive points in time. We examined the correspondence of FRPs derived from the sleep-independent, the sleep-dependent, and the reset hypotheses, with FRP of intact BN. On both SOREMP and non-SOREMP nights, none of the 3 models corresponded with BN. Thus, we suggest that, for both SOREMP and non-SOREMP nights, intervening wakefulness cancels the pre-awakening REM rhythm, and a new REM rhythm starts with or without SOREMP. We discuss factors influencing the rate of SOREMP occurrence (SOREMP %), such as circadian effect, individual differences, length of interruption, and pre-awakening NREM duration.

Adult↗
PubMed1987

Sleep onset REM periods observed after sleep interruption in normal short and normal long sleeping subjects.

Among about 1000 male college students, 6 short and 5 long sleepers were finally selected on the basis of their responses to a sleep habit questionnaire. The subjects slept in the laboratory for 6 consecutive nights. On nights 4, 5 and 6, deliberate sleep interruption was performed during the second sleep cycle. During interruption, subjects were asked to perform 3 different kinds of tasks on each of the 3 nights. Stage REM latencies after interruption were distributed bimodally with peaks at sleep onset after the interruption (sleep onset REM period: SOREMP) and 50-60 min later (non-SOREMP). SOREMPs were observed only in the sleep of short sleepers. Short sleepers showed a shorter sleep latency and a greater amount of stage REM in the 2nd and the 3rd sleep cycle of their baseline sleep record than did long sleepers. These characteristics of short sleepers' sleep and sleep interruptions probably affected the occurrence of SOREMPs. The mean duration of SOREMPs was significantly shorter than that of non-SOREMPs.

Adolescent↗
PubMed1987

High prevalence of isolated sleep paralysis: kanashibari phenomenon in Japan.

In Japan, a set of experiences called kanashibari is considered identical with isolated sleep paralysis. We investigated this phenomenon by means of a questionnaire administered to 635 college students (390 men and 245 women). Of all subjects, about 40% had experienced at least one episode of kanashibari [subjects of K(+)]. Therefore, isolated sleep paralysis is apparently a more common phenomenon than is usually appreciated. About half of the subjects of K(+) reported that they had been under "physical or psychological stress" or in a "disturbed sleep and wakefulness cycle" immediately before the episode. Many subjects of K(+) experienced the first episode in adolescence. In the distribution of age of first attack, the peak occurred at an earlier age in women subjects than in men subjects. These findings suggest that two factors influence the occurrence of the phenomenon. One is exogenous physical or psychological load and the other is endogenous biological development.

Adolescent↗
PubMed1987

Differences in sleep-wake habits and EEG sleep variables between active morning and evening subjects.

This article is a survey study, followed by an experimental study, examining the differences of sleep-wake habits and sleep electroencephalographic (EEG) variables between morning and evening type subjects (Ss). In the survey study, the Japanese version of the Horne and Ostberg Morningness-Eveningness Questionnaire and Life Habits Inventory (LHI) were administered to approximately 1,500 university students. The survey results showed that the two types were significantly different from each other in terms of retiring and arising time, sleep latency, mood on arising, nap, adequate amount of sleep, number of times of staying awake all night, and variability in bedtime, arising time, and sleep length. These results suggested that evening type Ss had more irregular and/or flexible sleep-wake habits than morning type Ss. In the experimental study, 10 morning and 11 evening type Ss were selected from the population included in the survey study, and polysomnograms were obtained. The results showed that only in rapid eye movement (REM) latency did morning type Ss significantly differ from evening type Ss. REM latency might be related to personality factors, particularly to neuroticism and anxiety.

Adolescent↗
PubMed1986

[The results of investigation by the Japanese version of Morningness-Eveningness Questionnaire].

Morningness-Eveningness Questionnaire (MEQ) developed by Horne & Ostberg (1976) was translated into Japanese, and then, MEQ and Life Habits Inventory were administered to approximately 1,500 university students. The distribution of MEQ scores was essentially normal, and the reliability of this questionnaire was high (r alpha = .702). Comparing among the morning, evening, and intermediate types, it was found that the morning type retired and arose significantly earlier than other types, although there was no significant differences in sleep length. Furthermore, there were significant differences between the morning and evening types in sleep latency, mood on arising, adequate amount of sleep, frequency and duration of nap, and number of staying awake all night per month. These results suggested that the evening type had more irregular sleep-waking habits than the morning type. Since the above results were obtained only from student population, further investigation on various populations is requested.

Adult↗