The Measurement of Sleep: A Practical Workshop for Investigators Polysomnography

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The Measurement of Sleep A Practical Workshop
for InvestigatorsPolysomnography
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
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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 whats 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

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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

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Delta REM Counts and vPSG Sleep Histogram
Compute Total power Relative power For
All Night Individual Sleep Cycles
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QEEG Bandwidths
Delta .5 4 Hz.
Theta 4 8 Hz.
Alpha 8 - 12 Hz.
Sigma 12 - 16 Hz.
Beta 16 32 Hz.
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Delta Power and VPSG Sleep Histogram
Compute Total power Relative power For
All Night Individual Sleep Cycles
Example
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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)

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Participants

• General
• PI and GSC recruited in 31 ratio
• Age 20-50 years, men and women
• Medical history, psychiatric history (SCID),
  sleep disorders history, screening PSG (AHI,
  PLMAI lt 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

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Power-frequency plots Whole night
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Power-frequency plots by NREM period Women
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Power-frequency plots by NREM period Men
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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

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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
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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
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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) ? gt 21,120 HRV Output LF power, HF
power, LFHF Ratio, Respiration Rate, etc.
W W W W W W
2 3 3 4 4
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vPSG HRV
WAKE NREM
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NREM differs from Wakefulness REM
HF Power LFHF
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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
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How Many LFHF HRV Epochs During NREM Sleep Are
Enough?
Number of LFHF HRV epochs during NREM for G
0.8 NREM Whole Night 13 NREM 1 13 NREM 2
15, NREM 3 17, NREM 4 7
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Does HF HRV During NREM Sleep Change Across The
Night?
Time F (3,100) 2.43, p lt .07
Time F(3,100)2.43, p lt .07
Time F(3,100)2.43, p lt .07
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Does LFHF HRV During NREM Sleep Change Across
The Night?
Time F (3,99) 3.99, p lt .02
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STUDY 1 Acute Laboratory Stress
Ambient Stress Acute Stress
Heart Period Variability
Sleep Quality
Experimental Manipulation
Sleep
800 p.m.
a.m.
SUBJECTS 59 healthy undergraduate men and women
(50 female, mean age 19.6 years).
Hall et al., Psychosomatic Medicine, 2004
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Parasympathetic Activity During NREM and REM
Sleep
NREM REM
Parasympathetic Activity high frequency
bandwidth (0.15-0.4 Hz)