The Measurement of Sleep: A Practical Workshop for Investigators Polysomnography Patrick J. Strollo M.D. Martica Hall, Ph.D. Neuroscience – Clinical & Translational Research Center Laboratory Team Pittsburgh Mind-Body Center on Sleep Workshop Pittsburgh, PA April 11, 2008

Agenda Brief review of polysomnography (PSG) Goal: Learn what is meant by poly (many) somnus (sleep) graphein (to write) Tour of N-CTRC sleep laboratory Goal: learn about the different types of studies that can be conducted in the N-CTRC Meet sleep technician and sleep study “participant” to see what’s involved in using PSG to measure sleep Goal: learn what all of the electrodes & monitors measure Watch as signals are collected from participant and review how different signals change with behavior Goal: learn what different signals look like Review examples of sleep pathologies Goal: learn about some of the signals that indicate sleep pathologies Review two kinds of advanced signal processing Goal: learn what is meant by spectral analysis of the EEG and EKG during sleep

Advanced Signal Processing Spectral analysis of signals collected during sleep studies What is spectral analysis? Decompose a complex, multi-determined signal Move from time to frequency domain (power is variability2) Spectral analysis of the EEG Example: EEG profile in patients with insomnia differs by gender and across the night Spectral analysis of heart rate variability Example 1: Methods Example 2: Lab stressor affects HRV during sleep

Delta & REM Counts and vPSG Sleep Histogram Compute: Total power Relative power For: All Night Individual Sleep Cycles

QEEG Bandwidths Delta .5 – 4 Hz. Theta 4 – 8 Hz. Alpha 8 - 12 Hz. Sigma 12 - 16 Hz. Beta 16 – 32 Hz.

Delta Power and VPSG Sleep Histogram Compute: Total power Relative power For: All Night Individual Sleep Cycles Example…

Frequency and time domain analysis of EEG power during NREM sleep in primary insomnia Supported by MH24652, RR024153, RR00052 (D. Buysse, PI) Insomnia is a clinical disorder with sleep and waking symptoms Etiology uncertain, but hyperarousal often felt to be a critical component Subjective symptoms Hypothalamic-pituitary-adrenal axis Functional neuroanatomy using FDG PET studies Beta power in quantitative EEG during NREM Krystal SLEEP 2002; Perlis Sleep Med Rev 2001, Perlis J Sleep Res 2001; Merica Eur J Neurosci 1998)

Participants General PI and GSC recruited in 3:1 ratio Age 20-50 years, men and women Medical history, psychiatric history (SCID), sleep disorders history, screening PSG (AHI, PLMAI < 15) PI (n = 48) DSM-IV Primary Insomnia PSQI ≥ 7 No specific quantitative criteria by diary or PSG GSC (n = 25) No sleep disorder PSQI ≤ 5 Equated for age and sex with PI

Power-frequency plots: Whole night

Power-frequency plots by NREM period: Women

Power-frequency plots by NREM period: Men

Heart Rate Variability: What is it? Heart rate is rhythmic and varies dynamically in response to intrinsic and extrinsic inputs and demands (CNS activity, mechanical changes, reflex-related changes, behavior, psychological stress, affect). Interbeat intervals (IBIs) refer to milliseconds between beats. Evaluate in the time domain or frequency domain. Two main components of HRV Low frequency changes (~3-9 cycles/min.) Multiply-determined: input from PNS and SNS High frequency changes (9-24 cycles/min.) Related to PNS (‘vagal’ ‘RSA’) Low-to-High frequency ratio Index of sympatho-vagal activity

Frequency Domain Estimates of HRV (QEKG) 60-minute IBI sequence 10 (shaded) minute IBI sequence Power spectral estimates of variability in 10-minute IBI epoch (raw, smoothed) IBI variability is partitioned along a frequency spectrum using frequency-modeling techniques (e.g., fast Fourier Transformations (FFTs), autoregressive spectral analyses). Amount of variability (spectral power) is estimated for given frequency components (bandwidths). Low Frequency = .05-.149 Hz, High Frequency = .15 - .40 Hz Slide courtesy of Julian F. Thayer

DAILY: Fill out Sleep Diary and Wear Wrist Actigraph Sleep SCORE: Study Protocol (HL076379, Investigators: K. Matthews, M. Hall, D. Buysse, P. Strollo, T. Kamarck, S. Reis) DAILY: Fill out Sleep Diary and Wear Wrist Actigraph PSG Sleep Study (2 nights) Ambulatory BP (48 hours) DAY 1 DAY 10 EEG, EMG, EOG, EKG GNT GMT SCORING PSG visual sleep stage scoring in 20 second epochs EKG HRV processing in 2-minute epochs

Heart rate variability: Processing & linking HRV and vPSG data HRV records processed: 101 (Night 2) Mean sleep duration: 7 hours (420 minutes)  210 (2-minute) epochs  total number of epochs (101 x 210)  > 21,120 HRV Output: LF power, HF power, LF:HF Ratio, Respiration Rate, etc. vPSG HRV W W W W W W 2 3 3 4 4 3 WAKE NREM

NREM differs from Wakefulness & REM HF Power LF:HF

How Many HF HRV Epochs During NREM Sleep Are Enough? Number of HF HRV epochs during NREM for G = 0.8 NREM Whole Night = 5; NREM 1 = 7; NREM 2 = 7, NREM 3 = 6, NREM 4 = 3

How Many LF:HF HRV Epochs During NREM Sleep Are Enough? Number of LF:HF HRV epochs during NREM for G = 0.8 NREM Whole Night = 13; NREM 1 = 13; NREM 2 = 15, NREM 3 = 17, NREM 4 = 7

Does HF HRV During NREM Sleep Change Across The Night? Time F (3,100) = 2.43, p < .07 Time F(3,100)=2.43, p < .07 Time F(3,100)=2.43, p < .07

Does LF:HF HRV During NREM Sleep Change Across The Night? Time F (3,99) = 3.99, p < .02

STUDY 1: Acute Laboratory Stress Ambient Stress Acute Stress Heart Period Variability Sleep Quality Experimental Manipulation 8:00 p.m. Sleep a.m. SUBJECTS: 59 healthy undergraduate men and women (50% female, mean age = 19.6 years). Hall et al., Psychosomatic Medicine, 2004

NREM REM Parasympathetic Activity During NREM and REM Sleep Parasympathetic Activity = high frequency bandwidth (0.15-0.4 Hz)