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State child care regulations regarding infant sleep environment since the Healthy Child Care America-Back to Sleep campaign.

BACKGROUND: Despite overall decreases in sudden infant death syndrome deaths and prone sleeping, the proportion of sudden infant death syndrome deaths that occurs in child care settings has remained constant at approximately 20%. In 2003, the American Academy of Pediatrics' Healthy Child Care America program launched its own Back to Sleep campaign to promote the Back to Sleep message for those who care for young children. OBJECTIVES: The purpose of this study was to evaluate the effectiveness of the first 2 years of the Healthy Child Care America-Back to Sleep campaign in improving child care regulations by assessing the inclusion of the elements of a safe sleep environment in the individual state regulations for child care centers and family child care homes. METHODS: We examined regulations available in October 2005 for licensed child care centers and family child care homes in the 50 states and the District of Columbia for specific regulations pertaining to (1) sudden infant death syndrome risk-reduction training for child care providers, (2) infant sleep position, (3) crib safety, (4) bedding safety, (5) smoking, and (6) provision of information about sleep positioning policies and arrangements to parents before the infant is enrolled in child care. RESULTS: Since 2003, when the Healthy Child Care America-Back to Sleep campaign began, 60 of the 101 state regulations for either child care centers or FCCHs have been revised. More than half of these regulations written since 2003 mandate a nonprone sleep position and restrictions on soft bedding in the crib, and the change in these regulations since 2003 is statistically significant. However, of the 101 existing state regulations, only 49 require that infants sleep nonprone, 18 mandate sudden infant death syndrome training for child care providers, 81 have > or = 1 crib safety standard, and 43 restrict soft bedding in the crib. Only 4 regulations require that parents be provided with sleep policy information. CONCLUSIONS: The initial 2 years of the Healthy Child Care America Back to Sleep campaign have been successful in promoting safe infant sleep regulations. Efforts must continue so that safe sleep regulations exist in all jurisdictions.

Bedding and Linens↗

Blood pressure changes during daytime sleep and comparison of daytime and nighttime sleep-related blood pressure changes in patients with chronic renal failure.

Blood pressure has a diurnal pattern primarily related to activity and sleep. Chronic renal failure patients may lack the normal nocturnal decline in blood pressure during sleep. In 33 subjects (14 with normal renal function and 19 with renal dysfunction), the relationship between depth of daytime sleep, as determined by electroencephalographic sleep phase, and change in mean arterial blood pressure (MAP) and heart rate measured oscillometrically, was correlated. In 15 chronic renal failure patients, the effect of daytime and nighttime sleep on MAP and heart rate was compared. The percent change in night asleep versus day awake MAP and heart rate was measured (with Space Labs ambulatory blood pressure monitors) and compared with the percent change in daytime sleep-related MAP and heart rate measured during a daytime sleep electroencephalographic study. During daytime sleep, MAP changes are not significantly different in the normal versus renal dysfunction groups. In the 33 study subjects, MAP declines progressively from the upright position to Phase 3/4 sleep (118 +/- 3.6 to 106 +/- 3.6 mm Hg). The largest decline occurs between the upright to recumbent position, before sleep. Heart rate declines moving from the upright to recumbent position, 76 +/- 2.3 to 70 +/- 2.1 beats/min, but does not decline further with sleep. In 15 chronic renal failure patients, heart rate (10.8 +/- 2.8%; P < 0.05), but not MAP, declines during nighttime sleep. Both MAP (7.7 +/- 3.3%) and heart rate (5.4 +/- 1.9%) decline significantly during daytime sleep. The responses of MAP and heart rate to daytime and nighttime sleep were in opposite directions in 3 of 15 subjects.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Pressure↗

High incidence of diabetes in men with sleep complaints or short sleep duration: a 12-year follow-up study of a middle-aged population.

OBJECTIVE: The aim of this study was to investigate the possible relationship among sleep complaints, sleep duration, and the development of diabetes prospectively over a 12-year period in a middle-aged Swedish population. RESEARCH DESIGN AND METHODS: A random sample of 2,663 subjects aged 45-65 years living in mid-Sweden were sent a postal questionnaire including questions about sleep complaints, sleep duration, sociodemographic characteristics, behavioral risk factors, medical conditions, and depression (response rate 70.2%). Twelve years later, a new questionnaire with almost identical questions was sent to all the survivors (n = 1,604) in 1995, and the questionnaire was answered by 1,244 subjects (77.6%). RESULTS: Men reporting new diabetes at follow-up more often reported short sleep duration (< or =5 h per night) (16.0 vs. 5.9%, P < 0.01), difficulties initiating sleep (16.0 vs. 3.1%, P < 0.001), and difficulties maintaining sleep (28.0 vs. 6.3%, P < 0.001) at baseline than men who did not develop diabetes. Women reporting new diabetes at follow-up reported long sleep duration (> or =9 h per night) more often at baseline than women not developing diabetes (7.9 vs. 2.4%, P < 0.05). In multiple logistic regression models, the relative risk (95% CI) for development of diabetes was higher in men with short sleep duration (2.8 [1.1-7.3]) or difficulties maintaining sleep (4.8 [1.9-12.5]) after adjustment for age and other relevant risk factors. Short or long sleep duration or sleep complaints did not influence the risk of new diabetes in women. CONCLUSIONS: Difficulties maintaining sleep or short sleep duration (< or =5 h) are associated with an increased incidence of diabetes in men.

Aged↗

Poor compensatory function for sleep loss as a pathogenic factor in patients with delayed sleep phase syndrome.

OBJECTIVE: Delayed sleep phase syndrome (DSPS) is a condition in which the patient is unable to reset or phase-advance his/her sleep timing properly after transient sleep delay and consequently shows persistent sleep phase delay. Prior studies suggested that DSPS is associated with a phase delay in the circadian pacemaker, but there was no evidence to explain the patient's inability to reset sleep phase. SUBJECTS AND METHODS: We used an ultra-short sleep-wake schedule together with simultaneous measurement of dim light melatonin rhythm after 24-hour sleep deprivation to allow the differential observation of diurnal sleep propensity fluctuation both from circadian and homeostatic aspects in 11 patients with DSPS (17-37 years; 8 men, 3 women) and 15 healthy controls (19-32 years; 8 men, 7 women). SETTING: NA. PATIENTS OR PARTICIPANTS: NA. INTERVENTIONS: NA. RESULTS: DSPS patients showed less ability to compensate for previous sleep loss during their circadian day and first hours of their circadian nighttime determined by dim light melatonin onset compared with controls, while controls compensated for previous sleep loss at most circadian times. Though shapes of dim light melatonin rhythm did not differ between the groups, phase angle between melatonin and sleep propensity rhythms was wider in DSPS patients than in controls. CONCLUSIONS: These findings suggest that poor compensatory function for sleep loss predisposes DSPS patients to failure to reset their sleep phase. Our results provide implications for understanding not only the pathophysiology of DSPS but also the biological basis for why some people can change their sleep schedule easily according to personal or social demands while others cannot.

Adolescent↗

[Sleep of sleep research personnel--results of the Munster Congress survey].

Due to different knowledge of sleep and sleep disorders (i.e. focussing) sleep quality of sleep-researchers may be better or worse than the sleep of other scientists. On the Münster Congress for Sleep-research and Sleep medicine in March 1994 we investigated this question using the Pittsburger Sleep Quality Index (PSQI). 46 sleep researchers, 52 practitioners and 103 scientists of other disciplines from the Münster University filled out the questionnaire. Results show no difference in overall sleep quality between the three groups, but only sleep quality in the group of sleep researchers shows a bimodal distribution suggesting a subpopulation with more serious sleep problems. 10 to 15% of the total academic population can be regarded as "poor" sleepers. Especially the group of practitioners, in which we found the highest values of daytime sleepiness, seems to be a risk-population for sleep disorders.

Adult↗

Total sleep deprivation and the thyroid axis: effects of sleep and waking activity.

BACKGROUND: Circadian and sleep components modulate anterior pituitary release of thyrotropin (TSH), the chemical substance regulating the thyroid hormones, thyroxine (T4), and triiodothyronine (T3). The present study examined TSH, T4, and T3 concentrations across the wake-sleep boundary time (2300-0130 hours) before, during, and after a 64-h sleep deprivation paradigm. Additionally, adrenocorticotropic hormone (ACTH) and cortisol were measured as an index of hypothalamic-pituitary-adrenal axis activation. Activity levels and ratings of effort required to perform cognitive tasks were also incorporated to evaluate physical and cognitive load, respectively, across the study period. Assessing the combined effects of activity and sleep deprivation on thyroid hormone economy is relevant to the relationship of high physical and/or cognitive performance demands during sleep deprivation inherent in extended military operations and space exploration. METHODS: There were 12 healthy subjects who were monitored during a 2-d baseline period, 3 d of total sleep deprivation, and 2 nights of recovery sleep. Serum samples were collected at 2300 hours and 0130 hours across the entire study period, and measured for TSH, T4, T3, and glucocorticoids. RESULTS: Change scores evaluated at the wake-sleep boundary time demonstrated significant inhibitory effects of sleep on thyroid hormone measures. As expected, sleep deprivation was associated with elevated TSH. However, sleep deprivation also significantly increased circulating levels of T3 at 2300 hours and T4 concentration change scores (2300-0130 hours). Glucocorticoid levels did not track thyroid hormone changes. Physical activity remained constant while subjective ratings of effort to perform cognitive tasks increased significantly during sleep deprivation. CONCLUSION: Compared to sleep deprivation studies under constant conditions reporting no change in peripheral T4 and T3 levels, the present study suggests activity level, including cognitive effort to perform, during total sleep deprivation may produce substantive changes in the thyroid axis.

Adult↗

The effects of delta-sleep-inducing peptide (DSIP) on wakefulness and sleep patterns in the cat.

The effect of a single injection of synthetic delta-sleep-inducing peptide (DSIP, 7 nmol/kg) into the lateral ventricle of 10 cats was investigated by monitoring the sleep-wake cycle during an 8 h period. A significant decrease in sleep latency and a significant increase in total sleep and in total slow wave sleep (SWS) was found following DSIP administration. The increase in sleep resulted exclusively from a significant increase in deep slow wave sleep (S2), while light slow wave sleep (S1) was significantly decreased. Neither the total amount of REM sleep, nor hourly values of REM sleep were affected by DSIP application. Additional measures of REM sleep, like REM sleep latency, mean episode number and mean episode length were not different from those found in control conditions. DSIP was immediately effective since the amount of S2 increased to more than 50% in the first postinjection hour and the difference from the control value was highly significant. The increase in S2 was maintained over 7 h, and disappeared by the eighth hour. The increase in S2 was caused by a prolongation of S2 episodes and not by their more frequent occurrence. The results obtained suggest a sleep-facilitating property of DSIP.

Animals↗

Effects of sleep of restricted sleep. A cat case study.

One male cat was adapted to different schedules of restricted sleep. The cat was allowed to go to sleep during a certain number of hours per day. During the rest of the 24 h period, wakefulness was enforced by means of a treadmill. The following schedules of restricted sleep were run: 12 h sleep--12 h treadmill (12S--12T), 8S--16T, 4S--20T. The cat was also adapted to a 36 h day: 12S--24T. The sleep was investigated after at least 2 weeks on each schedule and compared to ad lib. sleep (24S--0T). As available sleep time bacame shorter, the composition of the sleep changed. LSWS (in % of available sleep time) decreased, while DSWS % and REM sleep % increased. The length of the DSWS and REM sleep episodes increased with decreasing sleep time, as did sleep cycle length.

Animals↗

Effects of social stimuli on sleep in mice: non-rapid-eye-movement (NREM) sleep is promoted by aggressive interaction but not by sexual interaction.

Sleep is generally considered to be a process of recovery from prior wakefulness. In addition to being affected by the duration of the waking period, sleep architecture and sleep EEG also depend on the quality of wakefulness. In the present experiment, we examined how sleep is affected by different social stimuli (social conflict and sexual interaction). Male C57BL/6J mice were placed in the cage of an aggressive dominant male or an estrous female for 1 h in the middle of the light phase. The conflict with an aggressive male had a pronounced NREM sleep-promoting effect. EEG slow wave activity, a measure of NREM sleep intensity, was increased for about 6 h and NREM sleep time was significantly increased for 12 h. REM sleep was strongly suppressed during the remainder of the light phase after the conflict, followed by a rebound later in the recovery phase. The sexual interaction, in contrast, had only mild effects. Both NREM sleep and REM sleep were somewhat suppressed shortly after the interaction. In a separate group of mice, blood samples were taken to measure prolactin and corticosterone. The results suggest that the temporary suppression of REM sleep following the social stimuli may be partly due to elevated corticosterone. The different effects of the social stimuli on NREM sleep are not easily explained by differences in the hormone responses. In conclusion, although both social conflict and sexual interaction induce a strong physiological activation, only social conflict has a strong stimulatory effect on NREM sleep mechanisms.

Aggression↗

Sleep regulation in the Djungarian hamster: comparison of the dynamics leading to the slow-wave activity increase after sleep deprivation and daily torpor.

STUDY OBJECTIVES: Emerging from daily torpor, Djungarian hamsters (Phodopus sungorus) show an initial increase in electroencephalographic slow-wave activity (power density between 0.75 and 4.0 Hz) during sleep that gradually declines. This feature is typical for sleep following prolonged waking and supports the hypothesis that sleep pressure increases during daily torpor. After hamsters were subjected to sleep deprivation or partial non-rapid eye movement sleep deprivation immediately following torpor, slow-wave activity remained high and decreased only when sleep was allowed. An analysis of the dynamics of the process underlying the build-up of sleep pressure during episodes of waking and torpor may provide insights into the regulation of normal sleep and wakefulness. We have analyzed in more detail the timecourse of the process that is common for waking and daily torpor and that could account for the subsequent increase in slow-wave activity. DESIGN: Continuous 24-hour recordings of electroencephalography, electromyography, cortical temperature, and electroencephalographic spectral analysis were performed. Torpor data of 28 hamsters and sleep-deprivation data of diverse durations collected previously in 15 hamsters were analyzed. SETTING: N/A. PATIENTS OR PARTICIPANTS: N/A. INTERVENTIONS: Sleep deprivation. MEASUREMENTS AND RESULTS: Slow-wave activity invariably increased as a function of the duration of both prior waking and torpor. However, the time constant of the build-up of slow-wave activity was approximately 2.75 times slower during torpor compared to sleep deprivation. Brain temperature recorded during the torpor bouts was 10 degrees to 12 degrees C below euthermic brain temperature. Therefore, the temperature coefficient of the time constant for the slow-wave-activity increase is between 2.3 and 2.8, a range typical for biochemical processes. CONCLUSIONS: We conclude that the processes occurring during daily torpor in the Djungarian hamster are similar to those occurring during sleep deprivation, but the build-up of sleep pressure during torpor appears to be slowed down by the lower brain temperature.

Animals↗

Cardiac changes during sleep in sleep-deprived infants.

OBJECTIVE: To evaluate the influence of a brief period of sleep deprivation on cardiac autonomic controls during sleep in healthy infants. DESIGN: Twelve healthy infants with a median age of 8 weeks (range, 7 to 18 weeks) were recorded polygraphically during a morning and an afternoon nap in a sleep laboratory. They were sleep deprived for approximately 2 hours, either in the morning or in the afternoon, before being allowed to fall asleep. Six infants were sleep deprived before the morning nap, and 6 before the afternoon nap. During both naps, their sleep, breathing, and heart-rate characteristics were continuously recorded. Spectral analysis of heart rate was evaluated as a function of sleep stages. Two major peaks were recognizable: a low-frequency component related to sympathetic and parasympathetic activities and a high-frequency component reflecting parasympathetic tonus. The ratio of low-frequency to high-frequency powers was calculated as an index of sympathovagal interaction. RESULTS: When sleep deprived, the infants had an increase in basal heart rate during non-rapid eye movement sleep (P=.021). With sleep deprivation, the ratio of low-frequency to high-frequency powers increased in non-rapid eye movement sleep (P=.005). These findings were consistent with an increase in sympathetic tone. CONCLUSION: Infants exposed to short-term sleep deprivation manifest changes in cardiac autonomic controls during sleep. These findings could be relevant to mechanisms associated with the sudden infant death syndrome.

Female↗

Sleep pressure score: a new index of sleep disruption in snoring children.

STUDY OBJECTIVES: Excessive daytime sleepiness (EDS), as measured by objective criteria, is infrequent in snoring children despite a high prevalence of EDS-related behavioral manifestations. We hypothesized that sleep architecture and arousal indexes may be altered relative to the severity of sleep-disordered breathing (SDB). DESIGN: Retrospective and prospective study. SETTING: Questionnaires were distributed through sleep clinic or school program; polysomnograms were performed at Kosair Children's Hospital in Louisville, Kentucky. PARTICIPANTS: To examine this issue, 182 children with SDB, 163 children with primary snoring, and 214 control children with a mean age of 6.9 +/- 2.6 years underwent polysomnographic evaluation in the laboratory. MEASUREMENTS AND RESULTS: Significant increases in slow-wave sleep (percentage of total sleep time) and decreases in rapid eye movement sleep (percentage of total sleep time) occurred in the SDB group (P < .0001). Spontaneous and respiratory arousal indexes and the apnea-hypopnea index (AHI) displayed negative and positive correlations, respectively, suggesting reciprocal interactions. Based on these observations, a sleep pressure score (SPS) was derived as a surrogate numeric measure for disrupted sleep homeostasis. The SPS exhibited linear increases relative to AHI, reaching a plateau at an AHI of 30 to 40 per hour of total sleep time. Furthermore, SPS values were significantly higher among African American and obese children (P < .0001). CONCLUSIONS: Sleep architecture is not preserved in children with SDB. An algorithm allowing for calculation of sleep propensity and disturbed sleep homeostasis in children who snore is proposed and may be of practical value in the assessment of sleepiness.

Body Mass Index↗

Association of usual sleep duration with hypertension: the Sleep Heart Health Study.

STUDY OBJECTIVES: Limited experimental data suggest that sleep restriction acutely elevates blood pressure; however, little is known about the relationship between usual sleep duration and hypertension. This study assesses the relationship between usual sleep duration and hypertension in a community-based cohort. DESIGN: Cross-sectional observational study. SETTING: The Sleep Heart Health Study, a community-based prospective study of the cardiovascular consequences of sleep-disordered breathing. PARTICIPANTS: Two thousand eight hundred thirteen men and 3097 women, aged 40 to 100 years. INTERVENTIONS: None. MEASUREMENTS AND RESULTS: Usual weekday and weekend sleep durations were obtained by questionnaire, and their weighted average were categorized as less than 6, 6 to less than 7, 7 to less than 8, 8 to less than 9, and 9 or more hours per night. Hypertension was defined as a systolic blood pressure of 140 mm Hg or greater, a diastolic blood pressure of 90 mm Hg or greater, or use of medication to treat hypertension. The relationship between sleep duration and hypertension was examined using categorical logistic regression with adjustment for age, sex, race, apnea-hypopnea index, and body mass index. Compared to subjects sleeping 7 to less than 8 hours per night, those sleeping less than 6 and between 6 and 7 hours per night had adjusted odds ratios for hypertension of 1.66 (95% confidence interval 1.35-2.04) and 1.19 (1.02-1.39), respectively, whereas those sleeping between 8 and 9 and 9 or more hours per night had adjusted odds ratios for hypertension of 1.19 (1.04-1.37) and 1.30 (1.04-1.62), respectively (p < .0001 for association of sleep duration with hypertension). These associations persisted when analyses were further adjusted for caffeine and alcohol consumption, current smoking, insomnia symptoms, depression symptoms, sleep efficiency, and prevalent diabetes mellitus or cardiovascular disease. CONCLUSIONS: Usual sleep duration above or below the median of 7 to less than 8 hours per night is associated with an increased prevalence of hypertension, particularly at the extreme of less than 6 hours per night.

Adult↗

Comparison of detrended fluctuation analysis and spectral analysis for heart rate variability in sleep and sleep apnea.

Sleep has been regarded as a testing situation for the autonomic nervous system, because its activity is modulated by sleep stages. Sleep-related breathing disorders also influence the autonomic nervous system and can cause heart rate changes known as cyclical variation. We investigated the effect of sleep stages and sleep apnea on autonomic activity by analyzing heart rate variability (HRV). Since spectral analysis is suited for the identification of cyclical variations and detrended fluctuation analysis can analyze the scaling behavior and detect long-range correlations, we compared the results of both complementary techniques in 14 healthy subjects, 33 patients with moderate, and 31 patients with severe sleep apnea. The spectral parameters VLF, LF, HF, and LF/HF confirmed increasing parasympathetic activity from wakefulness and REM over light sleep to deep sleep, which is reduced in patients with sleep apnea. Discriminance analysis was used on a person and sleep stage basis to determine the best method for the separation of sleep stages and sleep apnea severity. Using spectral parameters 69.7% of the apnea severity assignments and 54.6% of the sleep stage assignments were correct, while using scaling analysis these numbers increased to 74.4% and 85.0%, respectively. We conclude that changes in HRV are better quantified by scaling analysis than by spectral analysis.

Adult↗

Growth hormone-releasing hormone and corticotropin-releasing hormone enhance non-rapid-eye-movement sleep after sleep deprivation.

The neuropeptides growth hormone (GH)-releasing hormone (GHRH) and corticotropin-releasing hormone (CRH) regulate sleep and nocturnal hormone secretion in a reciprocal fashion, at least in males. GHRH promotes sleep and GH and inhibits hypothalamo-pituitary-adrenocortical (HPA) hormones. CRH exerts opposite effects. In women, a sexual dimorphism was found because GHRH impairs sleep and stimulates HPA hormones. Sleep deprivation (SD) is the most powerful stimulus for inducing sleep. Studies in rodents show a key role of GHRH in sleep promotion after SD. The effects of GHRH and CRH on sleep-endocrine activity during the recovery night after SD are unknown. We compared sleep EEG, GH, and cortisol secretion between nights before and after 40 h of SD in 48 normal women and men aged 19-67 yr. During the recovery night, GHRH, CRH, or placebo were injected repetitively. After placebo during the recovery night, non-rapid-eye-movement sleep (NREMS) and rapid-eye-movement sleep (REMS) increased and wakefulness decreased compared with the baseline night. After GHRH, the increase of NREMS and the decrease of wakefulness were more distinct than after placebo. Also, after CRH, NREMS increased higher than after placebo, and a positive correlation was found between age and the baseline-related increase of slow-wave sleep. REMS increased after placebo and after GHRH, but not after CRH. EEG spectral analysis showed increases in the lower frequencies and decreases in the higher frequencies during NREMS after each of the treatments. Cortisol and GH did not differ between baseline and recovery nights after placebo. After GHRH, GH increased and cortisol decreased. Cortisol increased after CRH. No sex differences were found in these changes. Our data suggest that GHRH and CRH augment NREMS promotion after SD. Marked differences appear to exist in peptidergic sleep regulation between spontaneous and recovery sleep.

Adult↗

Inhibition of brain interleukin-1 attenuates sleep rebound after sleep deprivation in rabbits.

It is hypothesized that interleukin-1 (IL-1) is involved in physiological sleep. If this hypothesis is correct, inhibition of IL-1 should attenuate sleep responses after sleep deprivation. We tested the effect of intracerebroventricular or intravenous injection of an IL-1 inhibitor, an IL-1 receptor fragment (IL-1RF), on sleep rebound after sleep deprivation in rabbits. Six hours of total sleep deprivation significantly increased non-rapid eye movement sleep (NREMS) and enhanced electroencephalogram slow-wave activity during NREMS. Intracerebroventricular treatment with the IL-1RF (50 micrograms) significantly attenuated the sleep responses after sleep deprivation. Furthermore, 1.0 mg/kg i.v. injection of the IL-1RF significantly suppressed spontaneous NREMS in rabbits that were not sleep deprived. However, intravenous administration of the IL-1RF (1.0 mg/kg) failed to attenuate the sleep responses following the 6-h sleep deprivation period. These results support the hypothesis that central pools of IL-1 are important for physiological sleep regulation.

Animals↗

Diabetes and sleep disturbances: findings from the Sleep Heart Health Study.

OBJECTIVE: To test the hypothesis that diabetes is independently associated with sleep-disordered breathing (SDB), and in particular that diabetes is associated with sleep abnormalities of a central, rather than obstructive, nature. RESEARCH DESIGN AND METHODS: Using baseline data from the Sleep Heart Health Study (SHHS), we related diabetes to 1). the respiratory disturbance index (RDI; number of apneas plus hypopneas per h of sleep); 2). obstructive apnea index (OAI; >or=3 apneas/h of sleep associated with obstruction of the upper airway); 3). percent of sleep time < 90% O(2) saturation; 4). central apnea index (CAI; >or=3 apneas [without respiratory effort]/h sleep); 5). occurrence of a periodic breathing (Cheyne Stokes) pattern; and 6) sleep stages. Initial analyses excluding persons with prevalent cardiovascular disease (CVD) were repeated including these participants. RESULTS: Of the 5874 participants included in this report, 692 (11.8%) reported diabetes or were taking oral hypoglycemic medications or insulin and 1002 had prevalent CVD. Among the 4872 persons without CVD, 470 (9.6%) had diabetes. Diabetic participants had worse CVD risk factor profiles than their nondiabetic counterparts, including higher BMI, waist and neck circumferences, triglycerides, higher prevalence of hypertension, and lower HDL cholesterol (P < 0.001, all). Descriptive analyses indicated differences between diabetic and nondiabetic participants in RDI, sleep stages, sleep time <90% O(2) saturation, CAI, and periodic breathing (P < 0.05, all). However, multivariable regression analyses that adjusted for age, sex, BMI, race, and neck circumference eliminated these differences for all sleep measures except percent time in rapid eye movement (REM) sleep (19.0% among diabetic vs. 20.1% among nondiabetic subjects, P < 0.001) and prevalence of periodic breathing (odds ratio [OR] for diabetic subjects versus nondiabetic subjects 1.80, 95% CI 1.02-3.15). Additionally, adjusted analyses showed diabetes was associated with nonstatistically significant elevations in the odds of an increased central breathing index (OR 1.42, 95% CI 0.80-2.55). Addition to the analysis of the 1002 persons with prevalent CVD (including 222 people with diabetes) did not materially change these results. CONCLUSIONS: These data suggest that diabetes is associated with periodic breathing, a respiratory abnormality associated with abnormalities in the central control of ventilation. Some sleep disturbances may result from diabetes through the deleterious effects of diabetes on central control of respiration. The high prevalence of SDB in diabetes, although largely explained by obesity and other confounders, suggests the presence of a potentially treatable risk factor for CVD in the diabetic population.

Aged↗

Sleep initiation and initial sleep intensity: interactions of homeostatic and circadian mechanisms.

Sleep initiation and sleep intensity in humans show a dissimilar time course. The propensity of sleep initiation (PSI), as measured by the multiple sleep latency test, remains at a relatively constant level throughout the habitual period of waking or exhibits a midafternoon peak. When waking is extended into the sleep period, PSI rises rapidly within a few hours. In contrast, sleep intensity, as measured by electroencephalographic slow-wave activity during naps, shows a gradual increase during the period of habitual waking. In the two-process model of sleep regulation, it corresponds to the rising limb of the homeostatic Process S. We propose that PSI is determined by the difference between Process S and the threshold H defining sleep onset, which is modulated by the circadian process C. In contrast to a previous version of the model, the parameters of H (amplitude, phase, skewness) differ from those of threshold L, which defines sleep termination. The present model is able to simulate the time course of PSI under baseline conditions as well as following recovery sleep after extended sleep deprivation. The simulations suggest that during the regular period of waking, a circadian process counteracts the increasing sleep propensity induced by a homeostatic process. Data obtained in the rat indicate that during the circadian period of predominant waking, a circadian process prevents a major intrusion of sleep.

Animals↗