MCAT Social and Behavioral Sciences : Sleep Cycles and Stages of Sleep

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Example Questions

Example Question #1 : Sleep Cycles And Stages Of Sleep

With regard to stages of sleep and consciousness, delta waves are most commonly associated with which of the following?

Possible Answers:

N2

N1

Wakefulness

N3

REM

Correct answer:

N3

Explanation:

The stages of sleep include three non-rapid eye movement (NREM) stages and one rapid eye movement (REM) stage. The stages proceed in the following order and cycle such that N1 follows REM: N1, N2, N3, REM.

During N1, the individual loses sensation of his or her environment and becomes more relaxed, both mentally and physiologically. Brain waves slowly transition from alpha waves (characteristic of wakefulness) to lower frequency theta waves.

During N2, environmental awareness completely disappears. Brain waves are characterized by sleep spindles and K-complexes, which are short bursts of higher frequency waves. General wave patterns follow theta wave trends, with the exception of these interruptions.

During N3, the individual enters deep sleep. Brain activity is characterized by a high presence of very low frequency delta waves. Parasomnias, such as sleepwalking and night terrors, can occur during stage N3 sleep.

REM sleep is characterized by neural acetylcholine secretions, which cause brain waves to increase in frequency and resemble alpha forms. The body's muscles are paralyzed, though the brain's activity is elevated. Dreams occur during this stage, and muscle paralysis is thought to prevent the sleeping individual from attempting to interact with their dreams.

 

Delta waves are most concretely linked to the N3 stage of sleep.

Example Question #1 : Sleep Cycles And Stages Of Sleep

Which of the following is characteristic of stage 1 of non-rapid eye movement sleep (NREM sleep)?

Possible Answers:

Electroencephalogram records delta activity.

Deep sleep occurs.

Eye movements are slow and electroencephalogram (EEG) shows low brain wave activity.

Electroencephalogram (EEG) activity is increased, with the appearance of spikes called K complexes.

Eye movement ceases, wave frequency is reduced, and wave amplitude is increased.

Correct answer:

Eye movements are slow and electroencephalogram (EEG) shows low brain wave activity.

Explanation:

The non-rapid eye movement stage of sleep, NREM or synchronized sleep, involves four stages. The transition from wakefulness to sleep occurs during stage 1. Eye movements are slow and the electroencepalogram (EEG) shows low brain wave activity. In stage 2, EEG activity is increased. Spikes called K complexes are recorded. In stage 3, eye movement ceases. Wave frequency is reduced and amplitude is increased. Delta activity is recorded on the EEG in stage 4. Stages 3 and 4 are considered deep sleep.

Example Question #1 : Sleep Cycles And Stages Of Sleep

Which of the following is recorded on electroencephalogram during deep sleep?

Possible Answers:

K complexes

Low brain wave activity

Decreased wave amplitude

Delta activity

Increased wave frequency

Correct answer:

Delta activity

Explanation:

Stages 3 and 4 of non-rapid eye movement sleep (NREM sleep) are considered deep sleep. Stage 3 is characterized by an increase in amplitude and a reduction of wave frequency. During stage 4 sleep, delta activity is recorded. Stage 1 is the transition from wakefulness to sleep. The EEG shows low brain wave activity. In stage 2, EEG activity is increased, with the appearance of spikes called K complexes.

Example Question #2 : Sleep Cycles And Stages Of Sleep

Which of the following is NOT a characteristic of non-rapid eye movement sleep (NREM sleep)?

Possible Answers:

Delta waves are recorded on an electroencephalogram (EEG)

Is also termed synchronized sleep

Dreaming

Respiration becomes slower and more regular

Comprises approximately 75% of the sleep cycle

Correct answer:

Dreaming

Explanation:

Sleep has two states: one with no rapid eye movement (NREM or synchronized sleep, which involves four stages) and one with rapid eye movements (REM or dreaming sleep). NREM sleep comprises approximately 75% of the sleep cycle. During NREM sleep, respiration becomes slower and more regular as transition from wakefulness to sleep occurs. During stage 4, or deep sleep, delta activity is recorded on the EEG.

Example Question #3 : Sleep Cycles And Stages Of Sleep

Which of the following is not a characteristic of rapid eye movement sleep (REM sleep)?

Possible Answers:

Penile erections may occur

Transition from wakefulness to sleep occurs

Respirations become more rapid and less regular

Dreams occur

Blood flow to the brain is increased

Correct answer:

Transition from wakefulness to sleep occurs

Explanation:

During rapid eye movement sleep (REM sleep), dreaming can occur. Blood flow to the brain is increased and breathing is more irregular. Penille erections may occur. The transition from wakefuness to sleep occurs during non-rapid eye movement sleep (NREM sleep). 

Example Question #6 : Sleep Cycles And Stages Of Sleep

Muscle paralysis normally occurs during __________.

Possible Answers:

stage 4 non-rapid eye movement sleep

stage 3 non-rapid eye movement sleep

rapid eye movement sleep 

stage 1 non-rapid eye movement sleep

stage 2 non-rapid eye movement sleep

Correct answer:

rapid eye movement sleep 

Explanation:

In rapid eye movement (REM) sleep, an electroencephalogram (EEG) shows low brain activity and muscle paralysis normally occurs. During non-rapid eye movement sleep (NREM), stage 1 eye movements are slow. EEG activity increases during NREM stage 2. Eye movement ceases during NREM stage 3. Delta wave activity occurs on EEG readings during NREM stage 4. NREM stages 3 and 4 are considered deep sleep.

Example Question #7 : Sleep Cycles And Stages Of Sleep

Which of the following physiological responses does not occur during rapid eye movement (REM) sleep?

Possible Answers:

Muscle paralysis normally occurs

Breathing is more irregular

Pulse become slower and more regular

Blood flow to the brain is increased

Metabolic rate increases

Correct answer:

Pulse become slower and more regular

Explanation:

During non-rapid eye movement (NREM)sleep, when the transition from wakefulness to sleep occurs, the pulse becomes slower and more regular. During rapid eye movement sleep (REM sleep), dreams occur, blood flow to the brain increases, breathing is more irregular, metabolic rate increases, and muscle paralysis occurs.

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