The role of the preoptic area (POA) neurons in the regulation of sleep-wakefulness (S-W) has been investigated in this study. The cell-specific neurotoxin, kainic acid (KA), was injected (0.8 microgram in 0.2 microliter) intracerebrally for lesioning of the POA. S-W was assessed (on the basis of EEG, EMG, and EOG recordings) for a day before bilateral lesion of the POA, and for 3 weeks after the lesion. There was an increase in wakefulness, and a decrease in all the stages of sleep after KA lesion of the POA. The reduction in deep slow wave sleep (S2) and REM sleep (PS) were more marked than light slow wave sleep (S1), and these had not shown any recovery even after 3 weeks of lesion. Two days after the lesion, the reduction in sleep was much more marked during the daytime than at night. There was an increase in locomotor activity, especially during the daytime, though it was only statistically significant on the 6th and the 10th day after the lesion. This study shows that the POA neurons are involved in the induction and maintenance of sleep. The lesion did not have a long lasting effect on the circadian distribution of sleep but the changes in locomotor activity seem to persist for a longer period.
Purpose:
Intermittent hypoxia and transient arousals in obstructive sleep apnea (OSA) can lead to poor sleep quality and acute stress. Rising levels of obesity and increased incidence of OSA in young adults predisposes them to acute stress. We propose a mediation model to assess if risk of OSA is associated with acute stress and if the relationship between risk for OSA and acute stress is mediated by sleep quality.
Methods:
493 healthy individuals (F=237, M=256) from 18-25 years of age (mean age=20.3+/-1.53 years) were screened for OSA, sleep quality and acute stress using STOP-BANG questionnaire, Pittsburg Sleep Quality Index and American Psychiatry Associations National Stressful Events Survey Acute Stress Disorder Short Scale (NSESS-S) respectively. Binary and logistic regression were used establish the relationships between the variables. Sobel test for mediation analysis was conducted.
Results:
73 participants (17.3%) were found at an intermediate and high risk of OSA by STOP BANG questionnaire. 79 (16%) participants reported level of stress as None. Mild, moderate and severe stress was present in 248 (50.3%), 109 (22.1%), 51 (10.3%) and 16 (3.2%) participants respectively. The odds of having severe and extreme stress among those at risk of sleep apnea is 2.18 times higher than that among those not at risk of sleep apnea (OR: 2.18, 95% Confidence Interval: 1.37-3.51). Sobel test established that the relationship between OSA and acute stress is mediated by sleep quality.
Conclusion
Sleep quality mediates the relationship between risk for sleep apnea and acute stress. This highlights the importance of screening for OSA in young adults, particularly young men with high BMI, presenting with high stress levels.
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