SEARCH · PubMed Health

Results for “Sleep Duration”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 163 records · Page 9Linked to original sources

PubMed2006

The relationship between depression and sleep disturbances: a Japanese nationwide general population survey.

OBJECTIVE: Among the existing epidemiologic studies that have examined the relationship between depression and sleep disturbances, there are few nationwide studies that have been conducted on subjects representing the general population. The present study was therefore conducted to clarify the relationship between depression and sleep disturbances, in particular the relationship between depression and both sleep duration and subjective sleep sufficiency, using a large sample representative of the general population. METHOD: The survey was conducted in June 2000, using self-administered questionnaires, targeting a population that was selected randomly from among 300 communities throughout Japan. Among the respondents, data from 24,686 individuals aged 20 years or older were analyzed. The Center for Epidemiologic Studies Depression Scale was used to assess the presence of depression. Sleep status, including sleep duration, subjective sleep sufficiency, and the presence or absence of insomnia symptoms, was evaluated. RESULTS: Those whose sleep duration was less than 6 hours and those whose sleep duration was 8 hours or more tended to be more depressed than those whose sleep duration was between 6 and 8 hours. Thus, sleep duration exhibited a U-shaped association with symptoms of depression. As subjective sleep sufficiency decreased, symptoms of depression increased, indicating a linear inverse-proportional relationship. CONCLUSION: The fact that sleep duration and subjective sleep sufficiency exhibited different relationships with symptoms of depression indicates that these 2 sleep parameters each have their own significance with regard to depression. These findings may be useful in the medical management of mental diseases.

Adult↗

PubMed2002

Physical exercise for sleep problems in adults aged 60+.

BACKGROUND: The prevalence of sleep problems in adulthood increases with age. While not all sleep changes are pathological in later life, severe disturbances may lead to depression, cognitive impairments, deterioration of quality of life, significant stresses for carers and increased healthcare costs. The most common treatment for sleep disorders (particularly insomnia) is pharmacological. The efficacy of non-drug interventions has been suggested to be slower than pharmacological methods, but with no risk of drug-related tolerance or dependency. Physical exercise, taken regularly, may promote relaxation and raise core body temperature in ways that are beneficial to initiating and maintaining sleep. OBJECTIVES: To assess the efficacy of physical exercise amongst older adults (aged 60 and above). SEARCH STRATEGY: We searched: MEDLINE (1966 - October 2001); EMBASE (1980 - January 2002), CINAHL ( 1982 - January 2002; PsychINFO 1887 to 2002; The Cochrane Library (Issue 1, 2002); National Research Register (NRR [2002]). Bibliographies of existing reviews in the area, as well as of all trial reports obtained, were searched. Experts in the field were consulted. SELECTION CRITERIA: Randomised controlled trials of physical exercise for primary insomnia where 80% or more of participants were over the age of 60. Participants must have been screened to exclude those with dementia and/or depression. DATA COLLECTION AND ANALYSIS: Abstracts of studies identified in searches of electronic databases were read and assessed to determine whether they might meet the inclusion criteria. Data were analysed separately depending on whether results had been obtained subjectively or objectively. MAIN RESULTS: One trial, including 43 participants with insomnia, examined the effectiveness of exercise in a population within an elderly population. At post-treatment, sleep onset latency improved slightly for both men and women. Total sleep duration, sleep onset latency and scores on a scale of global sleep quality showed significant improvement. Improvements in sleep efficiency were not significant. In some cases improvements indicated falls to below what are usually considered pathological levels but the wide confidence intervals and small sample size indicate that these findings must be interpreted with caution. REVIEWER'S CONCLUSIONS: When the possible side-effects of standard treatment (hypnotics) are considered, there is an argument to be made for clinical use of alternative treatments in the elderly. Exercise, though not appropriate for all in this population, may enhance sleep and contribute to an increased quality of life. Research involving exercise programmes designed with the elderly in mind is needed.

Aged↗

PubMed1985

Optimization of night and shiftwork plans among policemen in Kuwait: a field experiment.

A pilot survey was designed to define incidence, rotation period, rotation direction and cycle of shiftwork plans in the production and service units in Kuwait. Preliminary results from the Ministry of Interior showed that four different shift plans are widely used. Forty policemen, ten from each shift plan, volunteered to fill in a diary for a period of two or more cycles. The diary was comprised of a set of questions planned to reveal disturbances in sleep duration, sleep quality, food intake and appetite. The daily questionnaire also covered psychosomatic complaints and subjective judgement of recovery. A control group, on permanent day work, volunteered to fill in the diary for the same period. The results indicated that one of the four shift plans was quite satisfactory and least harmful to the policemen. Two plans were associated with excessive strain during working days, but the number of free days was sufficient to achieve complete recovery. The fourth plan was associated with excessive strain during working days and recovery was not achieved after 24 h of rest at the end of the shift cycle.

Adolescent↗

PubMed2003

Morning/evening menopausal formula relieves menopausal symptoms: a pilot study.

OBJECTIVE: The purpose of the study was to determine the efficacy of a morning/evening menopause formula (morning capsule contains panax ginseng, black cohosh, soy, and green tea extracts; evening capsule contains black cohosh, soy, kava, hops, and valerian extracts) for relieving menopausal symptoms such as hot flashes and sleep disturbance. METHODS: Healthy postmenopausal women, between 45 and 65 years of age, were asked to take the menopause formula orally, one capsule of the morning formula every morning and one capsule of the evening formula every evening for 2 months. The Greene Climacteric Scale (GCS) and the Pittsburgh Sleep Quality Index (PSQI) were used to determine the efficacy. RESULTS: Morning/evening menopause formula significantly reduced the number of hot flashes. The reduction in the number of hot flashes was observed as early as at the end of the second week. At the end of the second week, the number of hot flashes was reduced by 47%. The morning/evening menopause formula also significantly reduced the GCS total and subscale scores. At the end of the eighth week, the vasomotor, anxiety, and depression scores of GCS were reduced by 50%, 56%, and 32%, respectively. Furthermore, the morning/evening menopause formula significantly reduced global PSQI score and scores in five components (sleep quality, sleep latency, sleep duration, sleep disturbance, and daytime dysfunction) by 18%-46%. CONCLUSIONS: This study suggests that the morning/evening menopausal formula is safe and effective for relieving menopausal symptoms including hot flashes and sleep disturbance.

Cimicifuga↗

PubMed2006

Eszopiclone in patients with insomnia during perimenopause and early postmenopause: a randomized controlled trial.

OBJECTIVE: To evaluate eszopiclone 3 mg for treatment of insomnia in perimenopausal and early postmenopausal women, as well as the impact of insomnia treatment on mood, menopause-related symptoms, and quality of life. METHODS: This was a double-blind, placebo-controlled study with 410 women (aged 40-60; perimenopausal or early postmenopausal) who reported insomnia defined as sleep latency of at least 45 minutes and total sleep time less than or equal to 6 hours per night for at least 3 nights per week over the previous month. Patients were randomly assigned to eszopiclone 3 mg or placebo nightly for 4 weeks. Sleep data were collected once a day. Physician global assessments of menopause, menopause-specific questionnaire, Greene Climacteric Scale, the Montgomery Asberg Depression Rating Scale, and the Sheehan Disability Scale were collected at baseline and end of treatment. RESULTS: Patients receiving eszopiclone reported improvements in sleep induction, sleep maintenance, sleep duration, sleep quality, and next-day functioning relative to placebo (P<.05). Patients receiving eszopiclone reported fewer total awakenings and awakenings due to hot flushes (P<.05). Eszopiclone use led to greater improvement in Montgomery Asberg Depression Rating Scale scores (P<.05) and physician global assessments of menopause scores (P<.001); total Greene Climacteric Scale score and the vasomotor and psychological sub-scores (P<.05); vasomotor and physical domains of the menopause-specific questionnaire (P<.05); and family life/home domain of the Sheehan Disability Scale (P<.05). CONCLUSION: In this study, eszopiclone provided significant improvements in sleep and positively impacted mood, quality of life, and menopause-related symptoms in perimenopausal and early postmenopausal women with insomnia. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov www.clinicaltrials.gov NCT00366093 LEVEL OF EVIDENCE: I.

Affect↗

PubMed2005

Parental perception of sleep problems in children of normal intelligence with pervasive developmental disorders: prevalence, severity, and pattern.

OBJECTIVE: This study compares parents' perceptions of the prevalence, severity, and pattern of sleep problems in children of normal intelligence with pervasive developmental disorders (PDDs) with a normative comparison group of children. METHOD: A survey including the Children's Sleep Habits Questionnaire was mailed to a sample of parents of children (age range 5-12 years) with PDDs (diagnosed by the Autism Diagnostic Interview-Revised) obtained by chart review of the past 7 years and to parents of comparison children matched on age, gender, and postal code. RESULTS: The response rate in the PDD group was 82.2% (37/45) and 55.8% (43/77) in the comparison group. By individually matching, 23 pairs were obtained. The prevalence of sleep problems in the PDD group was reported by parents as being significantly higher than in the comparison group (78% and 26%, respectively; p < .002), as was the severity (mean score 48.2 and 39.0, respectively; p < .001). Values for four of eight sleep subscales including sleep onset delay, sleep duration, sleep anxiety, and parasomnias were significantly higher in the PDD group. CONCLUSIONS: Parents report that sleep problems are significantly more prevalent and severe in children of normal intelligence with PDDs compared with normally developing children, and the pattern appears diverse. Sleep problems in children with PDDs require further research and clinical attention.

Canada↗

PubMed1991

Nocturnal profile of growth hormone secretion during sleep induced by zolpidem: a double-blind study in young adults and children.

Overnight blood sampling for repeated growth hormone (GH) assays, regarded as the most physiological assessment of GH status, may induce some disturbances in patients' sleep and then in the evaluation of GH secretion. We studied the influence of a hypnotic drug, zolpidem (10 mg), on nocturnal GH profiles (GH peak, time to first and maximum GH peak, area under the curve, mean integrated concentration) over two nights at a 7-day interval, in a double-blind cross-over design in a group of 12 young adult volunteers (27.9 +/- 4.3 years), and in a group of 12 children (10.8 +/- 2.3 years) with short stature, in a parallel double-blind study. Mean GH profiles showed no difference between zolpidem-treated subjects and placebo-treated controls, either in adults or in children. Although in these experimental conditions, sleep onset latency was significantly reduced with zolpidem in the adult volunteers, the mean time to first GH peak remained unchanged. Furthermore, GH profile did not relate with sleep duration, sleep onset latency or number of awakenings. A hypnotic drug, such as zolpidem, given at bedtime, is therefore devoided of effect on nocturnal GH profile and may be used in young children for overnight blood sampling when needed.

Adolescent↗

PubMed1985

A double-blind controlled subjective study of a new pharmaceutical preparation of lormetazepam versus placebo in patients with chronic sleep disturbances.

A double-blind crossover trial was carried out on the sleep-inducing activity of a new preparation (oral drops) of lormetazepam versus placebo. Twenty patients were included and requested to subjectively evaluate their sleep, both by analogue scales and semiquantitative ratings, during 2-night administration of the two products. Also, the usual parameters, sleep duration, sleep latency and number of awakenings were evaluated. Lormetazepam drops appeared to exert the same actions as the capsules' preparation, being significantly different from those of the placebo.

Adult↗

PubMed2005

Cystic fibrosis patients have poor sleep quality despite normal sleep latency and efficiency.

STUDY OBJECTIVES: Cystic fibrosis (CF) patients may be predisposed to poor sleep quality due to upper and lower airway abnormalities and impaired gas exchange. Previous sleep investigations of CF patients using single-night polysomnography have reported conflicting results. We hypothesized that sampling sleep for a prolonged period in a patient's normal environment may give a more representative assessment of sleep quality than a single-night polysomnogram, and that impaired sleep quality would correlate with pulmonary disease severity and self-assessed sleep quality. DESIGN: Using wrist actigraphy, we measured sleep quality in clinically stable CF patients and age-matched control subjects. In addition, each CF patient and control subject completed the following three questionnaires: the Epworth sleepiness scale; the Pittsburgh sleep quality index (PSQI); and the Medical Outcomes Study 36-item short form. RESULTS: Twenty CF patients and control subjects were enrolled in the study, and were well-matched for age, sex, and body mass index. The mean (+/- SD) FEV(1) for CF patients was 61.0 +/- 20.1% predicted. CF patients and control subjects had similar sleep duration, sleep latency, and sleep efficiency. However, CF patients had higher PSQI scores (6.45 vs 4.55, respectively; p = .04), a higher fragmentation index (FI) [31.72 vs 18.02, respectively; p < 0.001], and less immobile time (88.87 vs 91.89, respectively; p = 0.02). There was a significant correlation of FI with FEV(1) and PSQI scores. CONCLUSIONS: Stable CF patients have disrupted sleep, and sleep disruption may in part be related to the severity of pulmonary disease. In addition, the PSQI may be useful in detecting CF patients with poor sleep quality.

Adult↗

PubMed2005

Sleep disturbances in midlife unrelated to 32-year diabetes incidence: the prospective population study of women in Gothenburg.

OBJECTIVE: To study the relation between diabetes incidence and sleep problems in a population-based sample of women followed for 32 years. RESEARCH DESIGN AND METHODS: The researchers conducted a prospective population study initiated in 1968-1969, with follow-ups in 1974-1975, 1980-1981, 1992-1993, and 2000-2001 in Gothenburg, Sweden. A total of 1,462 women born in 1908, 1914, 1918, 1922, and 1930, representative of women of the same ages in the general population, initially participated (90% participation rate). Reported sleep duration, sleep problems, and use of sleeping medication were related to incident diabetes from 1968 to 2000. Associations between sleep problems and diabetes were corrected for waist-to-hip ratio (WHR), BMI, subscapular skinfold, fasting blood glucose and serum lipid concentrations, blood pressure, heart rate, smoking, physical activity, education, and socioeconomic status. Additionally, associations between BMI, WHR, and sleep problems were examined. RESULTS: Over 32 years, 126 women (8.7%) developed diabetes. Associations between diabetes and initial sleep problems were tested in a Cox regression analysis, taking into consideration factors associated (P < 0.1) with diabetes. Sleep problems in 1968 did not increase risk of developing diabetes during the following 32 years. Obesity, particularly centralized, was associated with sleep problems. CONCLUSIONS: No association between sleep problems and developing diabetes was seen in this 32-year follow-up of middle-aged women. Obesity, on the other hand, known to cause increased risk of diabetes, was associated with current sleep problems.

Adult↗

PubMedDate not supplied

Comparison of subjective sleep quality in patients with cancer and healthy subjects.

PURPOSE/OBJECTIVES: To compare the subjective sleep quality of a group of patients with cancer undergoing treatment and a normative sample of healthy comparison subjects. DESIGN: Secondary analysis of data from a single time point in a repeated measures descriptive-correlational study. SAMPLE/SETTING: Convenience sample of 15 patients with cancer receiving antineoplastic therapy and admitted to a tertiary university medical center for fever or neutropenia and 52 healthy comparison subjects without sleep disturbances. Although both groups were of similar age, a higher percentage of men comprised the comparison group. METHODS: Patients completed the Pittsburgh Sleep Quality Index (PSQI) on the first day of hospitalization to reflect their perceptions of sleep for the month prior to hospitalization. Healthy comparison subject scores on the PSQI were obtained from a published report outlining psychometric properties of the PSQI (Buysse, Reynolds, Monk, Berman, & Kupfer, 1989). MAIN RESEARCH VARIABLES: Sleep latency, sleep duration, sleep efficiency, sleep disturbances, medication use, daytime dysfunction, and global sleep quality. FINDINGS: Patients with cancer reported significantly poorer overall sleep quality accompanied by more daytime dysfunction. The incidence of specific sleep disturbances, such as snoring and dyspnea, was not different between the groups. CONCLUSIONS: This small sample of patients reported significantly poorer sleep quality than an historical comparison group. Specific sleep disturbances commonly seen in the general population were not problematic for the patients with cancer. Limited sample size and use of an historical comparison group need to be considered in interpreting and applying these findings. Additional research is needed to further characterize the nature of sleep problems in patients with cancer. IMPLICATIONS FOR NURSING PRACTICE: Nurses need to assess sleep in their patients, including its impact on quality of life and functional status.

Adult↗

PubMed1998

Shift length as a determinant of retrospective on-shift alertness.

OBJECTIVES: This study examined the combined effects of shift length (8 versus 12 hours) and night-to-morning-shift changeover time (0600 versus 0700) on retrospective on-shift alertness ratings. METHODS: An abridged version of the Standard Shiftwork Index, which included retrospective alertness ratings, was completed by 4 groups of industrial shift workers. Two groups worked 8-hour shift systems and started their morning shifts at either 0600 or 0700; the other 2 groups worked 12-hour systems, starting their day shifts at either 0600 or 0700. RESULTS: The 8-hour workers reported considerably higher levels of alertness in the afternoon, while the 12-hour workers were more alert than the 8-hour workers in the morning and at 2200. Workers who started their shift around 0600 were less alert during the morning than those who started around 0700. The data suggested that the combined effects of working 8-hour shifts and starting the morning shift at around 0600 have particularly deleterious effects upon alertness. CONCLUSIONS: Effects on alertness can be explained in terms of differences in elapsed time on duty, sleep duration, sleep disruption, and chronic fatigue. The findings of this study appear to contradict previous research demonstrating that the major deleterious effects of extended shifts and delayed changeovers upon alertness occur at night. However, it is acknowledged that the absence of a difference in alertness at night may have been due to floor effects. Nevertheless, the implications of the alertness ratings for performance and safety, particularly during the afternoon, should not be ignored.

Adult↗

PubMed1990

[The productivity of female shift workers].

The productivity of female shift workers, working on a weekly rotating three-shift system, was examined. The afternoon shift was found to be the most productive and the night shift the least productive one. The greatest difference in productivity between shifts was found in the first two days of the week, when the productivity on night shift was significantly lower than that on the other two shifts. From the third day on there were no longer significant differences in productivity between shifts. The most productive and the least productive workers on night shift did not significantly differ in extraversion or in sleep duration after the night shift. Family responsibility was found to be associated with the duration of sleep after the night shift: married women slept significantly shorter after the night shift than unmarried women. However, this difference in sleep duration was not associated with productivity on night shift. Sleep duration after the afternoon shift (8 hours 40 minutes) was on average two hours longer than after the other two shifts. The difference in sleep duration after different shifts, along with circadian variations in alertness, readiness for work and performance efficiency, could be responsible for differences in productivity between shifts.

Adult↗

PubMed1999

Influence of stress duration on the sleep rebound induced by immobilization in the rat: a possible role for corticosterone.

In rats, recovery from short intense stress usually involves a sleep rebound characterized by an increase in slow-wave sleep and paradoxical sleep duration. However, a large body of evidence indicates that stressful situations lasting for several days or weeks can have deleterious effects on sleep quantity and quality, probably leading to an impairment of the sleep rebound. In this study, using immobilization as a stress model in the rat, we sought to determine the stress duration beyond which the sleep rebound disappears, as well as the mechanisms responsible for this suppression. In a first series of experiments, rats were immobilized for 30 min, 1h, 2h or 4 h. Slow-wave sleep rebounds evidenced after the different immobilization periods were, respectively, +32%, +25%, +9% and -0.2% and paradoxical sleep rebounds +57%, +88%, +103% and +21% compared with control recordings of the same animals. The sleep rebound thus disappeared when the duration of immobilization reached 4 h. In a second series of experiments, adrenalectomized rats were subjected to a 1 h immobilization, and showed an increased slow-wave sleep rebound ( + 44% compared to intact ones), whereas the paradoxical sleep rebound was slightly decreased and delayed. When glucocorticoid action was replaced by an intramuscular injection of dexamethasone, a glucocorticoid receptor agonist, the sleep rebound was suppressed (-3% in slow-wave sleep and -37% in paradoxical sleep). Lastly, in a third series of experiments, plasma corticosterone concentration was evaluated at different times in rats immobilized for 1 h or 4 h. Corticosterone concentration was higher in stressed animals than in control ones (+92%) and returned to baseline 4 h earlier in animals immobilized for 1 h compared with those stressed for 4 h. Therefore, corticosterone is probably involved in the suppression of the sleep rebound after long immobilization periods since (i) dexamethasone suppressed the stress-induced sleep rebound, and (ii) corticosterone was elevated for a longer period in the 4 h immobilization group. It is concluded that the reparative sleep rebound is suppressed after long and intense stress periods and that a prolonged glucocorticoid secretion could be one of the factors responsible for this effect. This deleterious effect on sleep could impair normal recovery and quick adaptation to a new situation, and could participate in the development of stress-related pathologies in humans.

Adrenalectomy↗

PubMed2005

Effects of exogenous melatonin on sleep: a meta-analysis.

Exogenous melatonin reportedly induces drowsiness and sleep, and may ameliorate sleep disturbances, including the nocturnal awakenings associated with old age. However, existing studies on the soporific efficacy of melatonin have been highly heterogeneous in regard to inclusion and exclusion criteria, measures to evaluate insomnia, doses of the medication, and routes of administration. We reviewed and analyzed (by meta-analysis) available information on effects of exogenous melatonin on sleep. A MEDLINE search (1980 to December 2003) provided English-language articles, supplemented by personal files maintained by the authors. The analysis used information derived from 17 different studies (involving 284 subjects) that satisfied inclusion criteria. Sleep onset latency, total sleep duration, and sleep efficiency were selected as the outcome measures. The study effect size was taken to be the difference between the response on placebo and the mean response on melatonin for each outcome measured. Melatonin treatment significantly reduced sleep onset latency by 4.0 min (95% CI 2.5, 5.4); increased sleep efficiency by 2.2% (95% CI 0.2, 4.2), and increased total sleep duration by 12.8 min (95% CI 2.9, 22.8). Since 15 of the 17 studies enrolled healthy subjects or people with no relevant medical condition other than insomnia, the analysis was also done including only these 15 studies. The sleep onset results were changed to 3.9 min (95% CI (2.5, 5.4)); sleep efficiency increased to 3.1% (95% CI (0.7, 5.5)); sleep duration increased to 13.7 min (95% CI (3.1, 24.3)).

Cross-Over Studies↗

PubMed2003

Caffeine consumption and weekly sleep patterns in US seventh-, eighth-, and ninth-graders.

OBJECTIVE: To survey caffeine use by seventh-, eighth-, and ninth-graders and relate its use to age, sex, sleep characteristics, and day of week METHODS: Students kept a daily, 2-week diary of their sleep times and use of caffeine containing drinks and foods. Data were analyzed by fitted multiple regression models RESULTS: A total of 191 students participated. Caffeine intake ranged between 0 and 800 mg/d. Mean use over 2 weeks ranged up to 379.4 mg/d and averaged 62.7 mg/d (corrected for underrepresentation in our sample of boys, who consumed more caffeine). Higher caffeine intake in general was associated with shorter nocturnal sleep duration, increased wake time after sleep onset, and increased daytime sleep. SLEEP PATTERNS: Mean bedtime was 10:57 PM, and mean wake time was at 7:14 AM. Older children delayed bedtime longer on weekends, and younger ones had longer nightly sleep durations. Sleep duration lengthened on weekends, reflecting the combined effects of the circadian timing system and a mechanism that regulates the duration of sleep. Caffeine (soda) consumption also increased on weekends, for reasons that may be primarily social CONCLUSIONS: Regardless of whether caffeine use disturbed sleep or was consumed to counteract the daytime effect of interrupted sleep, caffeinated beverages had detectable pharmacologic effects. Limitation of the availability of caffeine to teenagers should therefore be considered.

Adolescent↗

PubMed1994

Duration of hornet sleep induced by ether anesthesia is curtailed by exposure to sun or UV irradiation.

Irradiation of hornets anesthetized by diethyl ether curtails their sleep duration from the ordinary 20-30 min to a mere 2-3 min. This effect on sleep is dependent on the intensity of the sun irradiation or, when exposed to monochromatic UV at 366 nm, on the duration of the irradiation. Of the various hornet cuticular areas of the body, the yellow cuticular areas of the abdominal segments are the most sensitive to the treatment. We assume that the cuticles of both live and dead hornets act as a converter of light to electric energy.

Analysis of Variance↗

PubMed1993

The role of slow-wave sleep on the duration of quiet sleep in infants.

The duration of quiet sleep (QS) phases has been shown to increase during the first year of life. Slow-wave sleep (SWS) appears in about half of the QS phases beyond 20 weeks. In order to evaluate the role of SWS in the lengthening of QS phase duration during the first year of life, we looked at 48 normal full-term infants (aged between 1 and 54 weeks), recorded for a whole-night period. Records included electro-encephalogram (EEG) and other polygraphic parameters. Infants were separated into two groups: (1) those who did not show SWS episodes at all, and (2) those who show both QS phases with (QS SWS+) and without (QS SWS-) SWS episodes. In group 2 the duration of QS SWS+ was longer than that of QS SWS, as well as longer than that of QS of group 1. Group 1 had a duration of QS phases similar to that of QS SWS-. The duration of QS SWS+ depended both on the SWS latency and SWS duration. The lengthening of QS phases with age is accounted for by those phases containing SWS episodes, reflecting a maturational restructuring of QS.

Journal Article↗