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Question 1Foundational Sleep Technology Knowledge

Which EEG frequency range characterizes the alpha rhythm seen during relaxed wakefulness with the eyes closed?

  1. 8 to 13 Hz Correct answer.
  2. 15 to 30 Hz
  3. 4 to 7 Hz
  4. 0.5 to 2 Hz

Explanation

Alpha activity is defined as a rhythm of 8 to 13 Hz that is maximal over the occipital regions during relaxed wakefulness with eyes closed. It attenuates with eye opening or mental alerting. Slower and faster bands are named theta, delta, and beta respectively.

Question 2Foundational Sleep Technology Knowledge

Sleep spindles consist of a train of distinct waves in which frequency range?

  1. 4 to 7 Hz
  2. 0.5 to 2 Hz
  3. 22 to 30 Hz
  4. 11 to 16 Hz Correct answer.

Explanation

A sleep spindle is a train of distinct waves of 11 to 16 Hz (most commonly 12 to 14 Hz) lasting at least 0.5 second, maximal over central derivations. Spindles are a defining feature of stage N2 sleep. Their presence in the absence of other stage-defining events keeps the epoch in N2.

Question 3Foundational Sleep Technology Knowledge

How is a K-complex defined for scoring purposes?

  1. A sinusoidal wave of 0.5 to 2 Hz that appears only during REM sleep
  2. A well-delineated negative sharp wave followed by a positive component lasting at least 0.5 second Correct answer.
  3. A run of 4 to 7 Hz activity seen over the occipital region with eyes closed
  4. A burst of 11 to 16 Hz activity lasting at least 0.5 second in the central region

Explanation

A K-complex is a well-delineated negative sharp wave immediately followed by a positive component standing out from the background EEG, lasting at least 0.5 second, maximal over frontal regions. It is one of the events that defines stage N2. K-complexes can also occur in N3 but are not used to define REM.

Question 4Foundational Sleep Technology Knowledge

Which EEG pattern is expected during REM sleep?

  1. Low amplitude mixed frequency activity Correct answer.
  2. Prominent alpha rhythm occupying the entire epoch
  3. Continuous 0.5 to 2 Hz waves exceeding 75 microvolts
  4. Sleep spindles recurring every few seconds

Explanation

The REM EEG is described as low amplitude mixed frequency, often with sawtooth waves in central regions. Spindles and K-complexes are absent unless the epoch borders another stage. Alpha may appear briefly but does not dominate the epoch.

Question 5Foundational Sleep Technology Knowledge

What is the standard epoch length used when scoring a polysomnogram?

  1. 30 seconds Correct answer.
  2. 10 seconds
  3. 60 seconds
  4. 15 seconds

Explanation

The AASM scoring manual specifies 30-second epochs, with each epoch assigned a single sleep stage. Longer or shorter windows are used only in specific research or pediatric contexts, not in routine clinical scoring.

Question 6Foundational Sleep Technology Knowledge

Stage N3 is scored when slow wave activity occupies at least what percentage of an epoch?

  1. 10 percent
  2. 50 percent
  3. 20 percent Correct answer.
  4. 80 percent

Explanation

Stage N3 requires slow waves of 0.5 to 2 Hz with peak-to-peak amplitude greater than 75 microvolts over frontal regions for at least 20 percent of the epoch. The 20 percent threshold applies to adults. Once met, the epoch is N3 regardless of other features.

Question 7Foundational Sleep Technology Knowledge

How does chin EMG tone in REM sleep usually compare with the other sleep stages?

  1. It is at its lowest level of the night Correct answer.
  2. It is the highest of all stages
  3. It shows regular 4-second bursts throughout
  4. It matches the wakeful level exactly

Explanation

REM sleep is characterized by skeletal muscle atonia, so chin EMG reaches its lowest level of the study. Brief muscle twitches may still transiently appear. An epoch with REM-like EEG but sustained wake-level chin tone is not scored as REM.

Question 8Foundational Sleep Technology Knowledge

In a patient with a well-formed alpha rhythm, what EEG change marks the transition from stage W to stage N1?

  1. Onset of rapid eye movements
  2. Increase in alpha amplitude
  3. Attenuation of the alpha rhythm Correct answer.
  4. Appearance of sleep spindles

Explanation

Stage N1 begins when the alpha rhythm is attenuated and replaced by low amplitude mixed frequency activity in more than half of the epoch. Slow eye movements may accompany the change. Spindles and rapid eye movements belong to later stages.

Question 9Foundational Sleep Technology Knowledge

Which electrode pairing is standard for the left EOG channel?

  1. E2 below the right eye referred to M2
  2. O1 referred to the contralateral mastoid
  3. E1 below the left eye referred to M2 Correct answer.
  4. E1 above the left eye referred to the ipsilateral mastoid

Explanation

The left EOG uses E1, placed below the left outer canthus, referred to the right mastoid M2. The right EOG uses E2 above the right outer canthus referred to M1. This crossed referencing makes conjugate eye movements appear out of phase.

Question 10Foundational Sleep Technology Knowledge

What maximum electrode impedance is generally acceptable before a diagnostic recording begins?

  1. 0.5 kilohms
  2. 5 kilohms Correct answer.
  3. 20 kilohms
  4. 50 kilohms

Explanation

Electrode impedances should be 5 kilohms or less for reliable low-noise signals. Higher impedances increase susceptibility to 60 Hz interference and artifact. Very low values approaching each other are less important than keeping all electrodes below the threshold.

Question 11Foundational Sleep Technology Knowledge

Which sensor is preferred for detecting the airflow reduction of a hypopnea caused by partial obstruction?

  1. A pulse oximeter on the finger
  2. A snoring microphone on the neck
  3. A nasal pressure transducer Correct answer.
  4. A thermistor placed at the nares

Explanation

Nasal pressure transducers detect subtle flow limitation and partial reductions better than thermistors, which are better suited to detecting complete cessation of flow. Hypopnea scoring relies on the pressure signal. Oximetry and snoring channels do not measure airflow directly.

Question 12Foundational Sleep Technology Knowledge

Respiratory inductance plethysmography belts placed on the chest and abdomen are used primarily to do which of the following?

  1. Measure arterial oxygen saturation
  2. Detect snoring vibrations in the airway
  3. Measure airflow temperature at the nose
  4. Estimate respiratory effort and thoracoabdominal motion Correct answer.

Explanation

Inductance belts record changes in cross-sectional area of the rib cage and abdomen, providing an effort signal. Comparing the two belts helps identify paradoxical motion during obstructive events. They do not quantify airflow or oxygenation.

Question 13Foundational Sleep Technology Knowledge

For diagnostic polysomnography, the pulse oximeter averaging time should be no longer than which value?

  1. 3 seconds Correct answer.
  2. 60 seconds
  3. 30 seconds
  4. 12 seconds

Explanation

A short averaging time of 3 seconds or less preserves the temporal relationship between desaturations and respiratory events. Long averaging blurs this relationship and can falsely prolong or attenuate reported desaturations.

Question 14Foundational Sleep Technology Knowledge

A periodic limb movement is scored when the increase in anterior tibialis EMG lasts how long?

  1. 0.1 to 0.4 second
  2. 10 to 30 seconds
  3. 0.5 to 10 seconds Correct answer.
  4. More than 30 seconds

Explanation

A limb movement must produce an EMG increase of at least 8 microvolts above baseline lasting 0.5 to 10 seconds. A series requires at least four consecutive movements separated by 5 to 90 seconds. Movements shorter or longer than that window do not qualify.

Question 15Foundational Sleep Technology Knowledge

When scoring an arousal during REM sleep, which additional requirement applies?

  1. A K-complex must immediately precede the arousal
  2. A sleep spindle must follow the arousal
  3. The arousal must last at least 10 seconds
  4. There must be a simultaneous increase in chin EMG Correct answer.

Explanation

Because REM is a low-tone state, an arousal in REM requires an abrupt shift in EEG frequency together with a concurrent increase in chin EMG lasting at least 1 second. In NREM the EMG change is not required. The EEG shift must also last at least 3 seconds.

Question 16Foundational Sleep Technology Knowledge

Under AASM rules, which finding defines a hypopnea?

  1. A 30 percent drop with a 3 percent desaturation or an arousal Correct answer.
  2. A 50 percent airflow drop lasting at least 20 seconds
  3. A 90 percent drop in airflow with a 3 percent desaturation
  4. Any visible airflow reduction accompanied by snoring

Explanation

A hypopnea requires a peak signal excursion drop of at least 30 percent lasting at least 10 seconds, with either a 3 percent oxygen desaturation or an arousal. The recommended rule uses nasal pressure as the airflow signal. A 90 percent drop describes an apnea, not a hypopnea.

Question 17Foundational Sleep Technology Knowledge

In a healthy adult, one full non-REM to REM sleep cycle lasts approximately how long?

  1. 20 minutes
  2. 180 minutes
  3. 30 minutes
  4. 90 minutes Correct answer.

Explanation

Sleep cycles average about 90 minutes, with four to six cycles across a normal night. Early cycles contain more slow wave sleep and later cycles contain longer REM periods. This periodicity reflects an ultradian rhythm rather than a circadian one.

Question 18Foundational Sleep Technology Knowledge

Which sleep stage occupies the largest share of total sleep time in a healthy adult?

  1. Stage N3
  2. Stage N1
  3. Stage REM
  4. Stage N2 Correct answer.

Explanation

Stage N2 typically accounts for roughly 45 to 55 percent of total sleep time in adults. REM occupies about 20 to 25 percent and N3 about 15 to 20 percent. Stage N1 is the smallest portion, usually under 5 percent.

Question 19Foundational Sleep Technology Knowledge

What is the standard structure of a multiple sleep latency test?

  1. Five naps spaced 2 hours apart Correct answer.
  2. Three naps spaced 1 hour apart
  3. Four naps spaced 3 hours apart
  4. Two naps spaced 30 minutes apart

Explanation

The MSLT consists of five nap opportunities scheduled 2 hours apart, beginning 1.5 to 3 hours after the wake time of the preceding overnight study. Each nap is terminated after 20 minutes if no sleep occurs. A mean sleep latency of 8 minutes or less with two sleep onset REM periods supports narcolepsy.

Question 20Foundational Sleep Technology Knowledge

Sawtooth waves are most characteristic of which sleep stage?

  1. Stage N2
  2. Stage N1
  3. Stage N3
  4. Stage REM Correct answer.

Explanation

Sawtooth waves are notched, serrated 2 to 6 Hz waves seen over central regions, often just before rapid eye movements in REM sleep. They are considered a supportive feature for scoring REM. They are not required for the stage and do not define NREM stages.

Question 21Foundational Sleep Technology Knowledge

An epoch shows low amplitude mixed frequency EEG, conjugate rapid eye movements, and chin EMG at its lowest level of the study. Alpha rhythm is present in the occipital channel for more than half of the epoch. How should this epoch be scored?

  1. Stage N2, because low amplitude mixed frequency activity is present
  2. Stage N1, because alpha is not continuous
  3. Stage W, because alpha occupies more than half of the epoch Correct answer.
  4. Stage REM, because eye movements and low chin tone are present

Explanation

When alpha rhythm is present for more than half of an epoch in a patient who generates alpha, the epoch is scored as stage W regardless of other features. REM requires low chin EMG but also demands that the EEG not be dominated by waking alpha. Alpha dominance takes precedence over eye movements and tone.

Question 22Foundational Sleep Technology Knowledge

A patient is in stage N2 when a 5-second arousal occurs in the first half of an epoch. The remainder of the epoch shows low amplitude mixed frequency EEG with no K-complexes or spindles. How is the epoch scored?

  1. Stage W until spindles reappear later in the night
  2. Stage REM, because chin tone often drops after an arousal
  3. Stage N1, because the arousal resets staging
  4. Stage N2, because the arousal does not end the N2 period Correct answer.

Explanation

After an arousal during N2, the stage continues as N2 for subsequent epochs of low amplitude mixed frequency EEG without K-complexes or spindles. Staging changes only with a transition to W, N3, or REM, or after a major body movement followed by slow eye movements. An isolated arousal does not automatically restart the staging sequence.

Question 23Foundational Sleep Technology Knowledge

What is the effect of changing the EEG low-frequency filter from 0.3 Hz to 0.1 Hz?

  1. Alpha rhythm amplitude increases markedly
  2. 60 Hz interference is eliminated
  3. Slow wave amplitude increases and sweat artifact becomes more likely Correct answer.
  4. Muscle artifact is largely removed

Explanation

Lowering the low-frequency filter allows slower signals to pass, which increases the apparent amplitude of slow waves and also admits slow sweat and respiration artifact. The 0.3 Hz setting is standard for routine scoring. The low-frequency filter has no effect on 60 Hz interference.

Question 24Foundational Sleep Technology Knowledge

Which sequence defines a respiratory effort-related arousal?

  1. An arousal occurring without any change in breathing effort
  2. Ten or more periodic limb movements in a series
  3. A 90 percent airflow drop followed by a 4 percent desaturation
  4. A progressive increase in respiratory effort ending in an arousal after at least 10 seconds Correct answer.

Explanation

A RERA is scored when increasing respiratory effort or flattening of the nasal pressure signal leads to an arousal from sleep, the event lasts at least 10 seconds, and it does not meet criteria for apnea or hypopnea. Desaturation is not required. RERAs capture obstruction that resolves without a measurable gas exchange consequence.

Question 25Foundational Sleep Technology Knowledge

In the two-process model of sleep regulation, process S is best described as which of the following?

  1. A learned behavioral pattern reinforced by consistent bedtime routines and sleep hygiene
  2. A circadian oscillator generated by the suprachiasmatic nucleus of the hypothalamus
  3. An ultradian rhythm that repeats approximately every 90 minutes across the night
  4. A homeostatic sleep drive that builds during wakefulness Correct answer.

Explanation

Process S is the homeostatic component that accumulates during wakefulness and dissipates during sleep, often indexed by slow wave activity. Process C is the circadian component driven by the suprachiasmatic nucleus. Sleep timing and propensity reflect the interaction of the two processes.

Question 26Foundational Sleep Technology Knowledge

In the international 10-20 system, which electrode is located at the midpoint between the nasion and the inion along the midline?

  1. Pz
  2. Fz
  3. Oz
  4. Cz Correct answer.

Explanation

The midline electrodes are placed at 20% intervals from the nasion: Fz at 30%, Cz at 50%, Pz at 70%, and Oz at 80% of the nasion-inion distance. Cz therefore sits at the midpoint.

Question 27Foundational Sleep Technology Knowledge

Which eye movement pattern is characteristic of stage W with eyes open?

  1. Slow rolling movements
  2. Vertical blinks at 0.5 to 2 Hz Correct answer.
  3. Rapid irregular movements
  4. Sustained lateral deviation

Explanation

Wakefulness with eyes open typically shows conjugate vertical eye blinks occurring about 0.5 to 2 times per second. Slow rolling movements mark N1, and rapid irregular movements mark REM.

Question 28Foundational Sleep Technology Knowledge

What frequency range defines the alpha rhythm in adults?

  1. 14 to 30 Hz
  2. 8 to 13 Hz Correct answer.
  3. 0.5 to 2 Hz
  4. 4 to 7 Hz

Explanation

Alpha rhythm is an 8 to 13 Hz posterior dominant rhythm seen in relaxed wakefulness with eyes closed. It attenuates with eye opening.

Question 29Foundational Sleep Technology Knowledge

A K-complex is a negative sharp wave immediately followed by a positive component and must last at least how long?

  1. 0.5 second Correct answer.
  2. 0.4 second
  3. 0.25 second
  4. 0.1 second

Explanation

A K-complex must last at least 0.5 seconds. It consists of a negative sharp wave followed by a positive component.

Question 30Foundational Sleep Technology Knowledge

What is the standard duration of a polysomnography scoring epoch?

  1. 60 seconds
  2. 15 seconds
  3. 20 seconds
  4. 30 seconds Correct answer.

Explanation

Polysomnography epochs are scored in 30-second blocks. Sleep stages, arousals, and respiratory events are tabulated per epoch or per hour of sleep.

Question 31Foundational Sleep Technology Knowledge

An EKG artifact in the EEG channels is best recognized by which feature?

  1. A high-frequency muscle spike
  2. Coincidence with the QRS complex Correct answer.
  3. Continuous 60 Hz thickening
  4. A slow baseline sway

Explanation

EKG artifact appears as periodic sharp transients that align with the QRS complexes in the ECG channel. It is most obvious in referential derivations and in patients with short necks.

Question 32Foundational Sleep Technology Knowledge

Wrist actigraphy estimates sleep and wake primarily by detecting which variable?

  1. Body temperature
  2. Skin conductance
  3. Heart rate variability
  4. Movement Correct answer.

Explanation

Actigraphy uses a movement sensor, usually an accelerometer, to infer sleep-wake patterns from periods of activity and rest. It does not directly measure brain waves.

Question 33Foundational Sleep Technology Knowledge

In the Maintenance of Wakefulness Test, each trial usually lasts how long?

  1. 30 minutes
  2. 25 minutes
  3. 40 minutes Correct answer.
  4. 20 minutes

Explanation

The MWT typically consists of four trials of 40 minutes each, separated by 2-hour intervals. The MSLT uses 20-minute nap opportunities instead.

Question 34Foundational Sleep Technology Knowledge

Sleep spindles are best seen in which EEG derivation?

  1. C4-M1 Correct answer.
  2. Fp1-F3
  3. O2-M1
  4. F4-M1

Explanation

Sleep spindles are maximal over central regions, so C4-M1 or C3-M2 displays them best. Occipital derivations emphasize alpha, and frontal derivations emphasize slow waves.

Question 35Foundational Sleep Technology Knowledge

According to the Nyquist theorem, what minimum sampling rate is needed to digitize EEG activity up to 35 Hz without aliasing?

  1. 100 Hz
  2. 70 Hz Correct answer.
  3. 140 Hz
  4. 35 Hz

Explanation

The Nyquist theorem requires sampling at least twice the highest frequency of interest. For 35 Hz activity, the minimum is 70 Hz; clinical systems usually sample higher.

Question 36Foundational Sleep Technology Knowledge

On a PSG display, which sensitivity setting produces the largest deflection for a given EEG voltage?

  1. 20 µV/mm
  2. 10 µV/mm
  3. 7 µV/mm Correct answer.
  4. 15 µV/mm

Explanation

Sensitivity is expressed as input voltage per millimeter of deflection; lower µV/mm values produce larger deflections. Thus 7 µV/mm is more sensitive than 10, 15, or 20 µV/mm.

Question 37Foundational Sleep Technology Knowledge

Vertex sharp waves are most prominent at which scalp location and sleep stage?

  1. Occipital region in stage W
  2. Central region in stage N1 Correct answer.
  3. Temporal region in REM
  4. Frontal region in stage N3

Explanation

Vertex sharp waves are maximal at Cz and are a hallmark of late stage N1. They are sharply contoured negative waves lasting less than 0.5 seconds.

Question 38Foundational Sleep Technology Knowledge

Which frequency band corresponds to theta activity?

  1. 0.5 to 2 Hz
  2. 4 to 7 Hz Correct answer.
  3. 14 to 30 Hz
  4. 8 to 13 Hz

Explanation

Theta activity is conventionally 4 to 7 Hz. Alpha is 8 to 13 Hz, beta is above 13 Hz, and scoring delta is 0.5 to 2 Hz.

Question 39Foundational Sleep Technology Knowledge

In non-REM sleep, an arousal is scored when an abrupt EEG frequency shift lasts at least how long?

  1. 1 second
  2. 5 seconds
  3. 3 seconds Correct answer.
  4. 10 seconds

Explanation

In NREM sleep, an arousal requires an abrupt shift of EEG frequency lasting at least 3 seconds. In REM sleep, the same EEG shift must be accompanied by a concurrent increase in chin EMG.

Question 40Foundational Sleep Technology Knowledge

For scoring stage N3, slow waves must have a peak-to-peak amplitude greater than what value?

  1. 100 µV
  2. 75 µV Correct answer.
  3. 50 µV
  4. 20 µV

Explanation

Slow waves for N3 scoring are 0.5 to 2 Hz with peak-to-peak amplitude greater than 75 µV, measured over frontal derivations. The 20% epoch criterion then determines whether N3 is scored.

Question 41Foundational Sleep Technology Knowledge

Which description best characterizes rapid eye movements in REM sleep?

  1. Conjugate and sharply peaked Correct answer.
  2. Slow and pendular
  3. Vertical and blink-like
  4. Regular and sinusoidal

Explanation

REMs are conjugate, irregular, and sharply peaked eye movements. Slow pendular movements are typical of N1, and blinks are vertical wake movements.

Question 42Foundational Sleep Technology Knowledge

In periodic limb movement scoring, the interval between consecutive limb movements must fall within which range?

  1. 0.5 to 4 seconds
  2. 5 to 90 seconds Correct answer.
  3. 90 to 120 seconds
  4. 1 to 5 seconds

Explanation

Periodic limb movements are separated by intervals of 5 to 90 seconds, with the movement itself lasting 0.5 to 10 seconds. The PLM index is the number per hour of sleep.

Question 43Foundational Sleep Technology Knowledge

The oxygen desaturation index is defined as the number of desaturations of at least what magnitude per hour of sleep?

  1. 1%
  2. 5%
  3. 10%
  4. 3% Correct answer.

Explanation

The ODI counts desaturations of at least 3% from the immediately preceding baseline, expressed per hour of sleep. Some laboratories also report a 4% index for billing or research.

Question 44Foundational Sleep Technology Knowledge

During CPAP titration, which outcome is the primary goal?

  1. Keep SpO2 below 90%
  2. Raise the arousal index above baseline
  3. Reduce the AHI to less than 5 per hour Correct answer.
  4. Eliminate snoring only

Explanation

CPAP titration aims to find a pressure that eliminates respiratory events, usually targeting an AHI below 5 per hour and adequate oxygenation. Snoring alone is not the primary endpoint.

Question 45Foundational Sleep Technology Knowledge

Sleep efficiency is calculated by dividing total sleep time by which value and multiplying by 100?

  1. Number of arousals
  2. Total recording time
  3. Total wake time
  4. Time in bed Correct answer.

Explanation

Sleep efficiency equals total sleep time divided by time in bed, multiplied by 100. It reflects how much of the bed period is spent asleep.

Question 46Foundational Sleep Technology Knowledge

In infant polysomnography, active sleep is most closely equivalent to which stage in older children and adults?

  1. Stage N2
  2. Stage N1
  3. REM sleep Correct answer.
  4. Stage N3

Explanation

Infant active sleep corresponds to REM sleep, with rapid eye movements, low chin EMG, and mixed-frequency EEG. Quiet sleep corresponds to NREM sleep.

Question 47Foundational Sleep Technology Knowledge

In a bipolar EEG derivation, activity that is identical at both electrodes is largely eliminated by which principle?

  1. Phase reversal
  2. High-frequency filtering
  3. Impedance matching
  4. Common-mode rejection Correct answer.

Explanation

A differential amplifier subtracts one input from the other, so a signal identical at both electrodes cancels out. This is common-mode rejection; phase reversal instead indicates a focal signal at one input.

Question 48Foundational Sleep Technology Knowledge

A 50 µV calibration signal is applied at a sensitivity of 5 µV/mm. What deflection should appear?

  1. 5 mm
  2. 25 mm
  3. 50 mm
  4. 10 mm Correct answer.

Explanation

Deflection in millimeters equals the input voltage divided by the sensitivity in µV/mm. A 50 µV signal at 5 µV/mm therefore produces 10 mm of deflection.

Question 49Foundational Sleep Technology Knowledge

Which measure is most commonly used as a marker of circadian phase in research settings?

  1. Sleep efficiency
  2. Dim-light melatonin onset Correct answer.
  3. Arousal index
  4. Apnea-hypopnea index

Explanation

Dim-light melatonin onset is a widely used circadian phase marker because melatonin secretion rises in the evening under dim light. Sleep efficiency and respiratory indices describe sleep quality, not circadian timing.

Question 50Foundational Sleep Technology Knowledge

Which finding meets the AASM criterion for sleep-related hypoventilation in an adult?

  1. PaCO2 >55 mmHg for 10 minutes Correct answer.
  2. SpO2 <90% for at least 1 minute
  3. EtCO2 >45 mmHg for 5 minutes
  4. Respiratory rate <12 breaths/min for 10 minutes

Explanation

Adult sleep-related hypoventilation is scored when PaCO2 exceeds 55 mmHg for at least 10 minutes during sleep, or rises by more than 10 mmHg above wake to exceed 50 mmHg. Isolated brief desaturations or low respiratory rate do not meet the criterion.