Overview

This lecture covers the assessment of vigilance, focusing on the different dimensions of sleepiness and the main objective tests used in sleep medicine, including MSLT, MWT, PVT, SART, and actigraphy.

Dimensions and Definitions of Sleepiness

• Sleepiness has multiple dimensions: ability to fall asleep, ability to stay awake, sustained attention, automatic behavior, difficulty waking up, and increased sleep need.
• Excessive daytime sleepiness is the inability to stay awake in inappropriate situations and is often improved by sleep.
• Fatigue differs from sleepiness: it is persistent tiredness, not relieved by sleep, and worsens with activity.
• Hyperomnia is defined as needing more than 11 hours of sleep per 24 hours.

Subjective Assessment

• Subjective sleepiness is evaluated via history taking and self-report scales.
• The Epworth Sleepiness Scale has 8 items and categorizes sleepiness levels based on sum scores.
• Fatigue is assessed with the Fatigue Severity Scale, using 9 items averaged for a final score.

Objective Tests for Vigilance

• The ideal vigilance test should cover all sleepiness dimensions, distinguish normal vs. pathological sleepiness, assess severity, and be accessible and easy to use.

Multiple Sleep Latency Test (MSLT)

• Measures ability to fall asleep using mean sleep latency and number of sleep-onset REM (SOREM) episodes.
• Diagnostic for narcolepsy; five 20-minute nap sessions conducted after overnight PSG.
• Influenced by sleep before the test, age, and number of naps performed.
• Not quickly or widely accessible; has variability in normative cut-offs and results.

Maintenance of Wakefulness Test (MWT)

• Measures ability to stay awake; patient sits in a quiet, dark room and tries not to fall asleep in four 40-minute sessions.
• Used for assessing driving ability; outcome is mean sleep latency.
• Motivation and instructions strongly influence results; not diagnostic.

Performance-Based Tests (PVT & SART)

• Psychomotor Vigilance Test (PVT): reaction time test over 10 minutes; measures lapses and accuracy.
• Sustained Attention to Response Task (SART): go/no-go test assessing response inhibition and decision-making; not diagnostic.
• Both are quickly and easily administered, but measure different dimensions.

Actigraphy

• Wearable device records movement to approximate sleep duration, allowing assessment of hyperomnia over multiple days.

Clinical Considerations

• Subjective and objective measures of sleepiness often poorly correlate and should be assessed independently.
• No single test is sufficient; comprehensive profiles using multiple markers are increasingly recognized as necessary.

Key Terms & Definitions

• Vigilance — the ability to maintain wakefulness and attention.
• Sleepiness — physiological tendency to fall asleep.
• Excessive Daytime Sleepiness (EDS) — inability to stay awake in unsuitable situations.
• Fatigue — persistent, unrelieved tiredness affecting body, emotion, and cognition.
• Hyperomnia — need for >11 hours sleep in 24 hours.
• MSLT — test measuring sleep latency and SOREM episodes.
• MWT — test of ability to stay awake over prolonged sessions.
• PVT — reaction time test assessing sustained attention.
• SART — go/no-go test assessing attention and inhibition.
• Actigraphy — device for objective long-term sleep/wake measurement.

Action Items / Next Steps

• Learn the key differences between subjective and objective sleepiness assessments.
• Review how to administer and interpret MSLT, MWT, PVT, SART, and actigraphy.
• Practice using the Epworth Sleepiness Scale and Fatigue Severity Scale.
• Prepare for exam questions on sleep disorder diagnostics and test selection.

The key differences between subjective and objective sleepiness assessments are:

Subjective Sleepiness Assessment

• Based on self-report: Patients provide information about their sleepiness through history taking and standardized questionnaires.
• Common tools: Epworth Sleepiness Scale (ESS) for sleepiness and Fatigue Severity Scale for fatigue.
• Reflects personal perception: Captures how sleepy or fatigued the patient feels in daily life.
• Advantages: Easy and quick to administer; provides insight into the patient's experience.
• Limitations: Can be influenced by patient awareness, mood, or motivation; may not correlate well with objective measures.

Objective Sleepiness Assessment

• Based on physiological or behavioral tests: Measures actual performance or physiological signs related to sleepiness.
• Common tests:
  • Multiple Sleep Latency Test (MSLT) — measures ability to fall asleep and sleep-onset REM episodes.
  • Maintenance of Wakefulness Test (MWT) — measures ability to stay awake.
  • Psychomotor Vigilance Test (PVT) and Sustained Attention to Response Task (SART) — assess sustained attention and reaction times.
  • Actigraphy — records movement to estimate sleep duration and patterns.
• Reflects actual sleep propensity or vigilance: Provides quantitative data on sleepiness or alertness.
• Advantages: Objective, less influenced by patient bias.
• Limitations: Can be time-consuming, require specialized equipment, and may be influenced by factors like motivation or prior sleep.

Important Note

• There is often a poor correlation between subjective and objective sleepiness, meaning both assessments are important and complementary for a comprehensive evaluation.

If you'd like, I can help summarize this into a study-friendly format!

Certainly! Here's a review of how to administer and interpret the main objective vigilance tests:

1. Multiple Sleep Latency Test (MSLT)

Purpose

• Measures the ability to fall asleep and detects sleep-onset REM (SOREM) episodes.
• Diagnostic for narcolepsy.

Administration

• Conducted after an overnight polysomnography (PSG) to ensure normal sleep.
• Typically 4 or 5 nap opportunities during the day, spaced 1.5 to 2 hours apart.
• Each nap lasts 20 minutes; if sleep occurs, extend by 15 minutes to capture possible SOREM.
• Patient lies in bed in a dark, quiet room.
• Avoid stimulants, sedatives, smoking, and caffeine before and during the test.
• Comfortable room temperature and no external distractions.

Interpretation

• Mean sleep latency: Average time to fall asleep across naps.
  • Normal: ~10-12 minutes (varies by age and number of naps).
  • Short latency (<8 minutes) suggests pathological sleepiness.
• Number of SOREM episodes: ≥2 SOREM episodes support narcolepsy diagnosis.
• Influenced by prior sleep, age, medications.

2. Maintenance of Wakefulness Test (MWT)

Purpose

• Measures the ability to stay awake in a quiet, non-stimulating environment.
• Often used to assess fitness to drive.

Administration

• Four sessions, each lasting up to 40 minutes, spaced about 2 hours apart.
• Patient sits comfortably in a dark, quiet room, instructed to stay awake as long as possible.
• No countermeasures allowed (e.g., no moving, talking, or looking away).
• Room temperature controlled; no bright light.
• Motivation and clear instructions are critical.

Interpretation

• Mean sleep latency: Average time patient stays awake.
  • Normal: Most healthy subjects stay awake for full 40 minutes.
  • Latency <15-22.5 minutes may indicate impaired wakefulness.
• Not diagnostic but useful for severity and treatment monitoring.
• Highly influenced by motivation.

3. Psychomotor Vigilance Test (PVT)

Purpose

• Assesses sustained attention and reaction time.
• Sensitive to sleep deprivation and sleepiness.

Administration

• Computer-based test lasting about 10 minutes.
• Visual stimuli (numbers) appear at random intervals.
• Subject presses a button as quickly as possible when stimulus appears.
• Measures reaction time, lapses (responses >500 ms), errors of omission.

Interpretation

• Increased lapses and slower reaction times indicate impaired vigilance.
• Sensitive to both acute and chronic sleep deprivation.
• Quick and easy to administer; widely available.
• Not diagnostic but useful for monitoring alertness.

4. Sustained Attention to Response Task (SART)

Purpose

• Measures sustained attention, response inhibition, and decision-making.
• Go/no-go task: respond to all stimuli except a specific "no-go" stimulus.

Administration

• Computer-based test where numbers appear on screen.
• Subject presses a button for every number except a designated one (e.g., "3").
• Measures commission errors (responding when should not) and omission errors.

Interpretation

• Higher error rates suggest impaired attention and inhibitory control.
• Not diagnostic for specific sleep disorders.
• Easy and quick to administer.
• Useful as part of a test battery assessing different vigilance dimensions.

5. Actigraphy

Purpose

• Objective, long-term measurement of sleep-wake patterns and sleep duration.
• Useful for assessing hyperomnia and circadian rhythm disorders.

Administration

• Wrist-worn device (like a watch) records movement continuously over days to weeks.
• Patient keeps a sleep diary to complement data.
• Data analyzed to estimate sleep periods and activity levels.

Interpretation

• Periods of low activity correspond to sleep; high activity to wakefulness.
• Sleep duration >11 hours per 24 hours suggests hyperomnia.
• Helps differentiate true hypersomnia from behavioral causes (e.g., irregular sleep schedules).
• Non-invasive and suitable for long-term monitoring.

If you want, I can help create a concise study guide or comparison table for these tests!

Here's a concise study guide to help you prepare for exam questions on sleep disorder diagnostics and test selection related to vigilance and sleepiness assessment:

Study Guide: Sleep Disorder Diagnostics & Test Selection

Key Concepts to Know

• Dimensions of Sleepiness: Ability to fall asleep, ability to stay awake, sustained attention, automatic behavior, difficulty waking up, increased sleep need (hyperomnia).
• Distinguish Sleepiness vs. Fatigue vs. Hyperomnia:
  • Sleepiness: tendency to fall asleep, improved by sleep.
  • Fatigue: persistent tiredness, not relieved by sleep, worsened by activity.
  • Hyperomnia: excessive sleep duration (>11 hours/24h).

Subjective Assessment Tools

• Epworth Sleepiness Scale (ESS): Measures subjective daytime sleepiness; scores >10 indicate abnormal sleepiness.
• Fatigue Severity Scale: Assesses fatigue severity; mean score >4 suggests significant fatigue.

Objective Tests Overview

Diagnostic Tips

• Use MSLT to confirm narcolepsy by identifying short sleep latency and SOREM episodes.
• Use MWT to evaluate ability to stay awake, especially for assessing driving safety.
• Use PVT and SART to assess cognitive vigilance and attention deficits related to sleepiness.
• Use Actigraphy for long-term monitoring of sleep duration and patterns, helpful in hyperomnia and circadian rhythm disorders.
• Always consider subjective reports alongside objective tests, as they often do not correlate well.

Common Exam Questions Examples

1. Which test is diagnostic for narcolepsy?
   Answer: Multiple Sleep Latency Test (MSLT) due to SOREM episodes.

2. How does the Maintenance of Wakefulness Test differ from the MSLT?
   Answer: MWT measures ability to stay awake; MSLT measures ability to fall asleep.

3. What is the main limitation of subjective sleepiness scales?
   Answer: They rely on patient self-report and may not correlate with objective measures.

4. Which test is best for assessing sustained attention and reaction time?
   Answer: Psychomotor Vigilance Test (PVT).

5. How is hyperomnia objectively assessed?
   Answer: Through actigraphy measuring sleep duration over multiple days.

If you want, I can help you create practice questions or a quick-reference chart for your exam prep!

Sure! Here's a guide to practicing the Epworth Sleepiness Scale (ESS) and the Fatigue Severity Scale (FSS), including how to use them and interpret the scores.

1. Epworth Sleepiness Scale (ESS)

Purpose

• Measures subjective daytime sleepiness.
• Helps identify excessive daytime sleepiness.

How to Use

• The patient rates their chance of dozing off or falling asleep in 8 different situations.
• Each situation is scored from 0 to 3:
  • 0 = would never doze
  • 1 = slight chance of dozing
  • 2 = moderate chance of dozing
  • 3 = high chance of dozing
• Situations include:
  1. Sitting and reading
  2. Watching TV
  3. Sitting inactive in a public place
  4. As a passenger in a car for an hour without a break
  5. Lying down to rest in the afternoon
  6. Sitting and talking to someone
  7. Sitting quietly after lunch without alcohol
  8. In a car, while stopped for a few minutes in traffic

Scoring

• Sum the scores for all 8 items.
• Interpretation:
  • 0–10: Normal range
  • 11–14: Mild excessive daytime sleepiness
  • 15–24: Moderate to severe excessive daytime sleepiness

Practice Example

Interpretation: Mild excessive daytime sleepiness.

2. Fatigue Severity Scale (FSS)

Purpose

• Measures the severity of fatigue and its impact on daily functioning.

How to Use

• The patient rates 9 statements about fatigue on a scale from 1 to 7:
  • 1 = strongly disagree
  • 7 = strongly agree
• Statements include items like:
  • “My motivation is lower when I am fatigued.”
  • “Exercise brings on my fatigue.”
  • “Fatigue interferes with my physical functioning.”
  • “Fatigue causes frequent problems for me.”

Scoring

• Calculate the mean score of the 9 items.
• Interpretation:
  • Mean score <4: No significant fatigue
  • Mean score ≥4: Significant fatigue

Practice Example

Interpretation: Significant fatigue.

If you want, I can help you create practice forms or quizzes to simulate filling out these scales!