Multiple sleep latency test (MSLT) and sleep apnea in aged women.

Sleep disturbance and the tendency to sleep during the day were assessed polysomnographically in 31 elderly women (mean age = 76.7 +/- 3.6 SD) recruited from a senior citizen's living facility without reference to sleep-wake complaints. The data showed that the level of sleepiness during the day in each subject depended in part on the severity of her respiratory disturbance. It was found that the group (n = 7) of elderly females with apnea and hypopnea index (AHI) higher than 20 was more sleepy [multiple sleep latency test (MSLT) = 7.9 +/- 2) than the group (n = 10) with AHI > 5 but less than 20 (MSLT = 12.7 +/- 5). Nevertheless, the presence and severity of respiratory disturbance were not the only factors that influenced the level of sleepiness during the day in the studied sample. A subgroup of four elderly females showed a marked sleepiness during the four tested periods (MSLT = 5.2 +/- 0.6) with a very low respiratory disturbance index (AHI = 5.5 +/- 0.8).

A factor replication of the Sleep-Wake Activity Inventory (SWAI) in a Mexican population.

The purpose of this study was to describe the factor structure of the Sleep-Wake Activity Inventory (SWAI) in a Mexican population. In a sample of 722 Mexican college students, we replicated five of the six factors originally described in the SWAI. Retained factors included: excessive daytime sleepiness (similarity coefficient of 0.735), psychic distress (0.609), social desirability (0.638), individual's ability to relax (0.864), and nocturnal sleep (0.660). These results confirm the factor structure and extend the possible utility of the SWAI in a siesta culture.

Super-reactivity to amphetamine toxicity induced by schedule of reinforcement.

The chronic exposure of rats to a schedule of operant water reinforcement coupled with chronically restricted access to water sensitized the animals to intermittent d-amphetamine injections (0.31-2.5 mg/kg with intervals of 12-23 days between any two injections) in such a way that this drug came to produce catastrophic losses of body weight (32.4% of control levels). In the sessions when d-amphetamine was administered, the rats were also given a total of 12 brief electric shocks. Loss of body weight was unaccompanied by parallel changes in operant behavior performance, or in food or water intake. Remarkably, in other studies with the same interventions (sham schedule sessions, water deprivation, and foot shocks), with the exception that reinforcers were never delivered, d-amphetamine did not produce catastrophic falls in body weight. This super-reactivity to d-amphetamine toxicity may be mediated by a possible stressor action of the schedule of reinforcement. Its mechanism might be analogous to the known sensitization produced by classical experimental stressor stimuli to the repeated administration of d-amphetamine.

Effects of indorenate on food intake: a comparison with fenfluramine and amphetamine.

Indorenate (TR3369, 5-methoxytryptamine b-methylcarboxylate HCl) is a 5-HT1-like receptor agonist with hypotensive activity. Here, we describe that indorenate also decreases food intake (ED50 26.1 mg/kg) without an appreciable effect in water intake (the estimated ED50 for water was 589.8 mg/kg). The anorectic activity of indorenate was compared to the effects of amphetamine and other serotonin agonists; the effect of indorenate was smaller than those of the other compounds; however, the effect of indorenate was specific to food, whereas all the other drugs also produced significant decrements in water intake. The serotonin antagonists cinanserin, cyproheptadine, methergoline and methysergide effectively prevented the decrease in food intake produced by indorenate and fenfluramine. Haloperidol, a dopaminergic antagonist, was ineffective in preventing the effect of indorenate although it prevented the anorectic effect of amphetamine. The present results suggest the participation of serotoninergic, but not dopaminergic mechanisms, in the decrease in food intake produced by indorenate.

Adipsic, but not anorectic, effect of fluprazine hydrochloride in rats.

The present experiment explored the anorectic and adipsic effects of fluprazine hydrochloride, a phenylpiperazine compound. Thirty-eight albino rats were randomly assigned either to a control saline group (six rats) or to groups (eight subjects each) receiving an IP dose of fluprazine in saline (1.25, 2.5, 5 or 10 mg/kg). No anorectic effect of the drug doses was observed 30, 60, 90, 120, 180 and 240 min, and 24 h after drug injection. However, water drinking was significantly decreased 30 min after drug administration, with 5 and 10 mg/kg, compared to saline.

Gender differences in sleep architecture in sleep apnoea syndrome.

This study compared sleep architecture in women and men with sleep apnoea syndrome. Women (n = 126) had longer sleep latencies, greater amounts of slow wave sleep, and fewer awakenings during the night than men (n = 181), despite no differences in age, RDI (Respiratory Disturbance Index) or oxygen saturation. In a subgroup of men and women treated with nasal CPAP, gender differences generally persisted. There was no difference in the complaint of daytime sleepiness between the groups, but the women reported more fatigue during the day than the men, as well as complaining about more sleep disturbance at night. We interpret these differences in terms of known gender differences in sleep architecture and sleep complaints.

Behavioral and biochemical correlates of chronic administration of quipazine.

In Experiment 1 groups of rats received single injections of 1, 3, 10, 20 or 40 mg/kg quipazine, and their total 24-hr food and water intake after a 24-hr deprivation period was recorded; there was a dose-related reduction of both food and water intake. In Experiment 2 a group of 15 rats received 5 mg/kg/day, SC quipazine during 29 days, and a control group received saline injections. During treatment, all animals were exposed to a 24-hr food and water deprivation schedule, alternated with 24 hr of free access. Food and water consumption was measured 2 and 24 hr after drug injection; regional 5-HT concentrations were determined at 1 and 13 treatment days by fluorometric assay. Beginning the first treatment day, food and water intake decreased, but by the 13th day the quipazine group had returned to normal ingestion levels. 5-HT concentrations were increased in cerebellum and cortex in acute conditions, but after 13 days they had decreased in cerebellar samples. In Experiment 3 we found that the effects of quipazine on food and water ingestion were recovered after 14 days of discontinuing chronic drug administration.

Sleep onset: scoring criteria in patients with sleep apnea syndrome.

It has been suggested that in patients with sleep apnea syndrome (SAS) modified scoring criteria may improve accuracy in the determination of sleep onset in the Multiple Sleep Latency Test (MSLT). Scoring in 30-sec epochs according to the standard criteria requires more than 50% of the epoch asleep to score sleep latency (SL). In patients with SAS, short apneas with arousals could prevent the accurate determination of SL. This study compared three time-duration epochs (5-sec, 10-sec, 30-sec) for scoring SL in patients with SAS. Sleep onset during a single sleep latency test, the morning subsequent to a nocturnal polysomnogram, was determined by the criterion of at least 50% of the epoch asleep. Neuropsychological evaluation was performed immediately after the single sleep latency test. There was no statistically significant difference in time to fall asleep as defined by 10-sec and 30-sec epochs, but SL defined by 5-sec epochs was significantly shorter than SL defined by 10-sec and 30-sec epochs. Wilkinson Addition Test correct score correlated better with SL as defined by 30-sec epochs. The results imply that the level of sleepiness measured by 30-sec epochs may be more useful to appreciate behavior and performance.

Cognitive function in patients with sleep apnea after acute nocturnal nasal continuous positive airway pressure (CPAP) treatment: sleepiness and hypoxemia effects.

Patients with sleep apnea are typically hypersomnolent during the daytime and may demonstrate higher order cognitive dysfunction. A persistent problem in interpreting impaired neuropsychological test performance in such patients is whether the observed deficits can be explained wholly by impaired vigilance. We examined 37 sleep apnea patients prior to and immediately subsequent to successful sleep apnea treatment with nasal continuous positive airway pressure (CPAP). Patients were evaluated immediately after morning awakening in the sleep lab. A brief neuropsychological evaluation, was administered at that time. Following this, alertness was measured with a 30-min polysomnographically determined sleep latency test. Both test (approximately 50 min in duration) were performed once following a baseline (diagnostic) night in the sleep lab and once in the morning following a CPAP (therapeutic) night in the lab. Subgroup analyses indicted that while vigilance impairment can account for some of the decreased test performance seen in sleep apnea (auditory verbal learning) the effects of severe nocturnal hypoxemia appear to affect other function (sustained attention in repetitive arithmetic calculations) that were not easily modified by treatment. Thus, performance on the recall trial of the Rey Auditory Verbal Learning Test increased from pre-CPAP to post-CPAP for the increased alertness group but decreased significantly for the decreased alertness group. On the Wilkinson Addition Test, non-hypoxemic patients showed statistically significant improvement in problems correctly solved from pre-CPAP to post-CPAP, but the hypoxemic patients showed only a marginal increase. These results are compatible with other studies suggesting that patients having sleep apnea may incur deficits as a result of both decreased vigilance and hypoxemia, and that at least some of these deficits are immediately reversible.

Prevalence and factors associated with fibromyalgia in Mexican patients with systemic lupus erythematosus.

In total, 189 consecutive women diagnosed with SLE were evaluated using the ACR 1990 criteria for fibromyalgia. Patients were classified into three subgroups. The fibromyalgia group (FM) included patients experiencing pain on palpation in at least 11 of the 18 tender points examined, as well as having a history of widespread pain for at least three months. Patients who were noted to have pain in fewer than four quadrants with less than 11 of 18 tender points were considered to have regional pain (RP). All patients who did not meet criteria for either FM or RP were classified as having no pain (NP). Measurement of SLE disease activity, sleep complaints, depression, fatigue severity and health status were performed. Only 18 of the SLE patients (9.5%) (95% CI 5.3-14%) fulfilled the ACR criteria for the classification of FM. Of the patients, 106 (56.1%) fulfilled criteria for RP and had a number of tender points of 5.4 +/- 3.4, and the rest of the patients (34.4%) had no tenderness at specific tender point sites. Age, body mass index, educational level and disease duration were comparable between the groups. FM and RP groups had different patterns of symptoms prevalence, with dysmenorrhea being more distinctive for FM. Sleep disturbances were more severe in the FM than in the RP group. Daytime complaints such as sleepiness, fatigue and depression were similar for RP and FM groups, but patients with FM reported more disability. Fibromyalgia is not common in Mexican patients with SLE and has a different pattern of symptoms in RP and NP patients. These data add evidence that ethnicity can play an important role in FM manifestations.

The siesta culture concept is not supported by the sleep habits of urban Mexican students.

Evidence in support for the concept of the so-called 'siesta culture' is not well developed and has, to date, relied largely on qualitative anthropological data. Presumably such cultures are characterized by a strong tendency for daytime naps and daytime sleepiness, phenomena which may partially represent the effects of geographic, climatic or light conditions and/or cultural influences. In this study we surveyed the nocturnal sleep habits and daytime sleep tendencies of 577 Mexican college students residing in Mexico City (19 degrees N latitude). Results indicated a number of parallels between the reported sleep habits of these students and those reported from other cultures at latitudes far to the north (North America, Europe), such as longer sleep at the weekends, an association between snoring and daytime sleepiness and a lack of relationship between nocturnal sleep duration and the reported tendency to nap. There was some suggestion that these Mexican students may actually nap less when compared to other college student populations. Taken together, these results call into question what is meant by the concept of a 'siesta culture', at least in this urban, educated, upper social economic scale (SES) population, and suggest that future studies in equatorial regions be undertaken to further appreciate the role of climate, photoperiod and/or culture in the tendency for humans to nap during the day.

Objective and subjective sleep disturbances in patients with systemic lupus erythematosus.

OBJECTIVE: To assess objective and subjective evidence of sleep disorders in patients with systemic lupus erythematosus (SLE) and to examine correlations between parameters of lupus activity, depression, and sleep disturbances. METHODS: Fourteen SLE patients and 11 normal control subjects of similar age underwent all-night polysomnography on 3 consecutive nights. The patients and controls were also evaluated for daytime sleepiness by the Multiple Sleep Latency Test and completed a sleep disorders questionnaire and the Beck Depression Inventory. RESULTS: The polysomnographic data showed that sleep in SLE patients was characterized by respiratory and movement disorders. These intrinsic primary sleep disorders are related to the symptom of restless, poor sleep at night. Lupus patients were more sleepy during the day, and their sleepiness was related to sleep fragmentation, with more arousals and stage transitions than the control group. Disease activity was associated with decreases in sleep efficiency and delta sleep and with increases in sleep fragmentation. Depression was not correlated with the activity of the disease. CONCLUSION: There is an enhanced presence of sleep disorders in patients with SLE. The most frequent primary sleep disorders are respiratory and movement disorders.

Prevalence of pulmonary hypertension and its association with respiratory disturbances in obese patients living at moderately high altitude.

OBJECTIVE: To determine the point prevalence of pulmonary hypertension (PH) and its relationship with respiratory disturbances in obese patients living at moderate altitude. SUBJECTS: A total of 57 obese patients comprised the final sample and consisted of 34 women and 23 men, with a mean age of 42.7+/-12.1 ys and a mean body mass index (BMI) 47.1+/-10.6 kg/m(2) (range from 30.1 to 76.1). The mean living altitude was 2248.7 m, range 2100-2400 m above sea level. MEASUREMENTS: Doppler echocardiography, pulmonary function tests, arterial blood gas analysis, and polysomnography were performed. RESULTS: Data showed that 96.5% of the studied sample had daytime PH defined as calculated systolic pulmonary artery pressure (PSAP) >30 mmHg (mean PSAP=50, s.d.=13 mmHg). The severity of diurnal PH was found to be related to the presence of alveolar hypoventilation and BMI. The main risk factor for severity of diurnal PH was hypoventilation with a significant odds ratio (OR) 7.96, 95% CI 1.35-46.84, BMI was (OR 1.12, 95% CI 1.02-1.25) and apnea/hypopnea index was not a predictor of pulmonary hypertension severity (OR 0.99, 95% CI 0.97-1.02). CONCLUSION: We concluded that prevalence of diurnal PH is high in obese patients living at moderate altitude, and that hypoventilation is the main risk factor associated with the severity of pulmonary hypertension.

Prevalence of sleep apnea and electrocardiographic disturbances in morbidly obese patients.

OBJECTIVE: To determine the prevalence of sleep apnea in morbidly obese patients and its relationship with cardiac arrhythmias. RESEARCH METHODS AND PROCEDURES: Fifty-two consecutive morbidly obese (body mass index > or = 40 kg/m2) outpatients from the Obesity Clinic of the National Institute of Nutrition Salvador Zubirán underwent two nights of polysomnography with standard laboratory techniques. Electrocardiographic polysomnography signals (Lead II) were evaluated by two experienced cardiologists, and sleep complaints were measured with a standard sleep questionnaire (Sleep Disorders Questionnaire). In order to make comparisons between groups with different severities of sleep-disordered breathing, we classified the patients in four groups using the apnea-hypopnea index (AHI): Group 1, AHI 5 < 15 (n = 10); Group 2, AHI 15 < 30 (n = 10); Group 3, AHI 30 < 65 (n = 14); Group 4, AHI > or = 65 (n = 17). RESULTS: A wide range of sleep-disordered breathing, ranging from AHI of 2.5 to 128.9 was found. Ninety-eight percent of the sample (n = 51) had an AHI > or = 5 (mean = 51 +/- 37), and 33% had severe sleep apnea with AHI > or = 65 with a mean nocturnal desaturation time of <65% over 135 minutes. Electrocardiographic abnormalities were present in 31% of the patients. Cardiac rhythm alterations showed an association with the level of sleep-disordered breathing and oxygen desaturation. DISCUSSION: We conclude that there is a high prevalence of sleep apnea in morbidly obese patients and that the risk for cardiac arrhythmias increases in this population in the presence of a severe sleep apnea (AHI > or = 65) with severe oxygen desaturation (SaO2 < or = 65%).