Cardiovascular Effects of Partial Sleep Deprivation in Healthy Volunteers

Volunteers Healthy young male volunteers from the urban area of Sao Paulo city will be recruited to the study. All subjects will be clinically evaluated, including measurements of weight and height. Exclusion criteria include age less than 21 and more than 45 years, body mass index (BMI) >25 kg/m2, smoking, use of chronic medications and any established medical condition including diabetes mellitus, hypertension, dyslipidemia, heart diseases and sleep disordered breathing. After obtaining written informed consent, all participants will be submitted to overnight polysomnography.

Polysomnography Overnight polysomnography will be performed to discarded sleep breathing using a digital system (17 channels, EMBLA Medicare - Flaga hf. Medical Devices). All polysomnograms will be performed and scored based on the guidelines for sleep studies. The apnea-hypopnoea index (AHI) was defined by the number of apneas and hypopnoeas per hour of sleep. Sleep disordered breathing was defined by an AHI above 5 events/hour, according to standard criteria.

Sleep Monitoring During the study period all subjects will be continuously monitored by a sleep diary and wrist actigraphy (Basic Mini Motionlogger Actigraph Ambulatory Monitoring, Inc., Ardsley , New York, USA ) worn on the non-dominant hand. The actigraph will set to sample movements in 1 min periods. Actigraph records will automatically process by use of the AW2 software version 2.3.01 program (Ambulatory Monitoring, Inc.) to extract information on sleep duration.

Blood Samples Venous blood will be collected from all participants between 8 and 10 AM for the measurement of glucose, total cholesterol, low-density lipoprotein, high-density lipoprotein, and red blood cell count. Plasma catecholamine (norepinephrine) will be measured by High-Performance Liquid Chromatography.

Hemodynamic and autonomic measurements Hemodynamic and autonomic evaluations will be performed in the morning between 8 and 10 AM. The intervals between adjacent QRS complexes resulting from sinus node depolarization will be determined (RR intervals). Heart rate will be calculated by expressing RR intervals as beats per minute. Non-invasive beat-to-beat blood pressure (Finometer, Finapres Medical System BV, Holland) and electrocardiogram (ECG) will be continuously recorded by the software AT/MCA-CODAS (DATAC Instruments Inc., Akron, Ohio, EUA). The sampling rate was 1000 Hz per channel.