Sleep architecture and composition
sleep disorders, sleep stage, Hypopnea, obstructive and central apnea, SE, Snoring
OBSTRUCTIVE SLEEP APNEA, EVENTS
Sleep architecture and composition are assessed by an ambulatory polysomnography, which represents the gold standard to objectively measure TST, sleep patterns and diagnose sleep disorders (e.g., obstructive sleep apnea, periodic limb movements). Patients undergo one night of home-based polysomnography (PSG) (Morpheus, Micromed, Italy). Sleep is assessed with standard PSG techniques using the 10–20 system [Hypopnea, obstructive and central apnea are assessed thanks to respiratory efforts with thoracic, abdominal inductance plethysmography (SleepSense, S.L.P. Inc., Elgin IL 60,124 USA) and with airflow, which is measured by a nasal pressure cannula (ThermoCan, SleepSense, S.L.P Inc., Elgin, IL, USA). Snoring is scored by filtration of the nasal pressure signal. Peripheral oxygen saturation (SpOPatients are instructed to maintain their habitual sleep patterns and asked to record the time of lights-out and the time immediately upon waking the next morning. PSG data are recorded directly to a data acquisition, storage, and analysis system (SleepRT™ software Suite Version 4.04.02 Buil5185; OSG, Belgium). The electroencephalogram (EEG) recordings are visually scored in 30-second periods, to obtain the overnight pattern of sleep stages, and respiratory events in 3-min periods for airflow by an experienced board-certified sleep physician using the American Academy of Sleep Medicine’s standard rules.The following sleep parameters are recorded: bedtime (h:min), wake-up time (h:min), time in bed (TIB, h), total sleep time (TST, h), sleep efficiency (SE, %), sleep onset latency (SOL, min, time from lights out to sleep onset, defined as the 1st epoch of any sleep stage (min), wake after sleep onset (WASO, min, number of minutes scored as wake-up time during sleep period, min), number of awakenings (nb), awake time (%), total time in stage 1 sleep (TTN1, min), percentage of stage 1 sleep in TST (N1, %), total time in stage 2 sleep (TTN2, min), percentage of stage 2 sleep in TST (N2, %), total time in stage 3 sleep (TTN3, min), percentage of stage 3 sleep in TST (N3, %), total time in rapid-eye movement sleep (TTREM, min) and percentage of REM sleep stage in TST (REM, %).