Insomnia and excessive sleepiness are common in the investigation of sleep-disordered breathing. Circadian rhythm sleep disorders are perhaps the most often overlooked conditions in the differential diagnosis of these symptoms. Circadian rhythm sleep disorders manifest as misalignment between the sleep period and the physical/social 24-h environmental cycle. The two most prevalent circadian rhythm sleep disorders are delayed sleep phase (common in adolescents) and advanced sleep phase (common in the elderly), situations in which the sleep period is displaced to a later or earlier time, respectively. It is important to keep these two disorders in mind, since they can be confused with insomnia and excessive sleepiness. However, there are nine possible diagnoses, and all nine are of clinical interest. Since light is the principal cue used in synchronizing the biological clock, blind individuals and night-shift/swing-shift workers are more prone to develop circadian rhythm sleep disorders. In this article, the new international classification of circadian rhythm sleep disorders is reviewed.

Keywords: Circadian rhythm; Sleep disorders; Sleep initiation and maintenance disorders; Sleep stages; Sleep apnea syndromes.

Objective: There are many ways of assessing sleepiness, which has many dimensions. In patients presenting a borderline apnea-hypopnea index (AHI, expressed as events/hour of sleep), the mechanisms of excessive daytime sleepiness (EDS) remain only partially understood. In the initial stages of sleep-disordered breathing, the AHI might be related to as-yet-unexplored EDS dimensions. Methods: We reviewed the polysomnography results of 331 patients (52% males). The mean age was 40 ± 13 years, and the mean AHI was 4 ± 2 (range, 0-9). We assessed ten potential dimensions of sleepiness based on polysomnography results and medical histories. Results: The AHI in non-rapid eye movement (NREM) stage 1 sleep (AHI-N1), in NREM stage 2 sleep (AHI-N2), and in REM sleep (AHI-REM) were, respectively, 6 ± 7, 3 ± 3 and 10 ± 4. The AHI-N2 correlated significantly with the greatest number of EDS dimensions (5/10), including the Epworth sleepiness scale score (r = 0.216, p < 0.001). Factor analysis, using Cronbach's alpha, reduced the variables to three relevant factors: QUESTIONNAIRE (α = 0.7); POLYSOMNOGRAPHY (α = 0.68); and COMPLAINTS (α = 0.55). We used these factors as dependent variables in a stepwise multiple regression analysis, adjusting for age, gender, and body mass index. The AHI-N1 correlated significantly with POLYSOMNOGRAPHY (β = −0.173, p = 0.003), and the AHI-N2 correlated significantly with COMPLAINTS (β = −0.152, p = 0.017). The AHI-REM did not correlate with any factor. Conclusions: Our results underscore the multidimensionality of EDS in mild sleep apnea.

Keywords: Disorders of excessive somnolence; Sleep apnea syndromes; Sleep, REM; Polysomnography.

Objective: To identify fibromyalgia syndrome in patients with sleep disordered breathing. Method: We studied 50 patients seeking treatment at a sleep disorder clinic for snoring, apnea and excessive daytime sleepiness. Sleep disordered breathing was diagnosed through the use of polysomnography. To diagnose fibromyalgia syndrome, patients were evaluated in accordance with the criteria established by the American College of Rheumatology. Results: Of the 50 patients, 32 were male. The mean (± standard deviation) age of the group was 50 ± 12 years. The mean body mass index was 29.7 ± 5.6 kg/m2. The mean apnea-hypopnea index was 36 ± 29 attacks of apnea or hypopnea per hour of sleep. Of the 18 women and 32 men evaluated, 9 and 2, respectively, met the American College of Rheumatology criteria for fibromyalgia syndrome. Conclusion: Considering the fact that the prevalence of fibromyalgia syndrome in the general population is 0.5% for men and 3.4% for women, the more than ten-fold higher proportion of fibromyalgia cases seen in this sample supports the hypothesis that there is an association between sleep disordered breathing and fibromyalgia syndrome.

Keywords: Respiration disorders/complications; Fibromyalgia/complications; Sleep apnea, obstructive; Polysomnography

Objective: To study the effects that gender and obesity have on excessive daytime sleepiness (EDS) in individuals with obstructive sleep apnea-hypopnea syndrome (OSAHS), as well as to identify factors associated with EDS in such individuals. Methods: A total of 300 consecutive patients who completed the clinical evaluation satisfactorily and whose polysomnography showed an apnea-hypopnea index (AHI) > 10 events/hour of sleep were selected from a sleep clinic population for inclusion in the study. Results: Mean age was 47 ± 11 years, and mean AHI was 52.1 ± 29.2 events/hour of sleep. Females presented higher mean age, lower EDS scores and less time in apnea . Mean EDS score was 14.7 ± 7.2. The EDS score correlated best with body movements (r = 0.43; p < 0.01), respiratory events during sleep (r = 0.40; p < 0.01), duration of apnea (r = 0.40; p < 0.01), peripheral oxygen saturation (SpO2; r = -0.38; p < 0.01) and AHI (r = 0.37; p < 0.01). Mean body mass index (BMI) was 30.2 ± 5.3 kg/m2. Overweight, obesity and morbid obesity were observed in 41, 44 and 5.3% of cases, respectively. Disease severity correlated most strongly with BMI (r = 0.51; p < 0.01). Conclusions: Higher mean age, lower EDS scores and less time spent in sleep apnea time in apnea were associated with being female. Fragmented sleep, number/duration of respiratory events during sleep, SpO2 levels and obesity were associated with sleepiness. The BMI had a significant effect on OSAHS severity.

Keywords: Sleep apnea, obstructive; Sleep apnea syndromes; Polysomnography; Sleep stages; Obesity.

Objective: To investigate the effect of intermittent hypoxia-a model of obstructive sleep apnea (OSA)-on pancreatic expression of uncoupling protein-2 (UCP2), as well as on glycemic and lipid profiles, in C57BL mice. Methods: For 8 h/day over a 35-day period, male C57BL mice were exposed to intermittent hypoxia (hypoxia group) or to a sham procedure (normoxia group). The intermittent hypoxia condition involved exposing mice to an atmosphere of 92% N and 8% CO2 for 30 s, progressively reducing the fraction of inspired oxygen to 8 ± 1%, after which they were exposed to room air for 30 s and the cycle was repeated (480 cycles over the 8-h experimental period). Pancreases were dissected to isolate the islets. Real-time PCR was performed with TaqMan assays. Results: Expression of UCP2 mRNA in pancreatic islets was 20% higher in the normoxia group than in the hypoxia group (p = 0.11). Fasting serum insulin was higher in the hypoxia group than in the normoxia group (p = 0.01). The homeostasis model assessment of insulin resistance indicated that, in comparison with the control mice, the mice exposed to intermittent hypoxia showed 15% lower insulin resistance (p = 0.09) and 21% higher pancreatic β-cell function (p = 0.01). Immunohistochemical staining of the islets showed no significant differences between the two groups in terms of the area or intensity of α- and β-cell staining for insulin and glucagon. Conclusions: To our knowledge, this is the first report of the effect of intermittent hypoxia on UCP2 expression. Our findings suggest that UCP2 regulates insulin production in OSA. Further study of the role that UCP2 plays in the glycemic control of OSA patients is warranted.

Keywords: Blood glucose; Sleep apnea syndromes; Pancreas; Glucagon-secreting cells.