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© A. Gonzalez-Mayo, R. Shaner, 2005
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Sleep Stages

Sleep is divided into two stages, nonrapid eye movement (NREM) and rapid eye movement (REM). There are numerous differences between these, which include:


A state of sleep characterized by slowing of the EEG rhythms, high muscle tone, absence of eye movements, and thoughtlike mental activity. In this state the brain is inactive while the body is active. NREM is made up of 4 stages:

EEG Findings
Stage 1 Disappearance of alpha wave and appearance of theta wave
Stage 2 k compelexes and sleep spindles
Stage 3 Appearance of delta wave
Stage 4 Continuation of delta wave

REM (Rapid Eye Movement)

A stage of sleep characterized by aroused EEG patterns, sexual arousal, saccadic eye movements, generalized muscular atony (except middle-ear and eye muscles), and dreams. In this state, the brain is active and the body is inactive.

EEG Findings
REM Bursts of sawtooth waves

Sleep Facts

Stage 2 Longest of all the sleep stages
Stages 3 and 4 Also called slow wave or delta sleep
Hardest to arouse
Tends to vanish in the elderly
REM Easiest to arouse
Lengthens in time as night progresses
Increased during the second half of the night

Figure 16-1. Sleep Architecture Diagram Showing Stages of Sleep in Sequence.

Figure 16-1. Sleep Architecture Diagram Showing Stages of Sleep in Sequence.

REM Latency

The period lasting from the moment you fall asleep to the first REM period. Lasts approximately 90 minutes in most individuals. However, several disorders will shorten REM latency; these disorders include depression and narcolepsy.

Sleep Latency

The time needed before you actually fall asleep. Typically less than 15 minutes in most individuals; however, may be abnormal in many disorders, such as insomnia, etc.

Characteristics of Sleep from Infancy to Old Age

  • Total sleep time decreases.
  • REM percentage decreases.
  • Stages 3 and 4 tend to vanish.

Neurotransmitters of Sleep

  • Serotonin: Increased during sleep; initiates sleep.
  • Acetylcholine: Increased during sleep; linked to REM sleep.
  • Norepinephrine: Decreased during sleep; linked to REM sleep.
  • Dopamine: Increased during sleep; linked to arousal and wakefulness.

Chemical Effects on Sleep

  • Tryptophan: Increases total sleep time.
  • Dopamine agonists: Produce arousal.
  • Dopamine antagonists: Decrease arousal, thus produce sleep.
  • Benzodiazepines: Suppress Stage 4 and, when used chronically, increase sleep latency.
  • Alcohol intoxication: Suppresses REM.
  • Barbiturate intoxication: Suppresses REM.
  • Alcohol withdrawal: REM rebound.
  • Barbiturate withdrawal: REM rebound.
  • Major depression: Shortened REM latency, increased REM time, suppression of delta, multiple awakenings, and early morning awakening.



A 35-year-old man was recently hospitalized for the tenth time after he crashed his car into a post. When questioned, he did not remember the cause of the accident and had just had his license suspended. His friends reported occasions when he fell asleep during dinner and during conversations with them.


A disorder characterized by excessive daytime sleepiness and abnormalities of REM sleep for a period of greater than 3 months. REM sleep occurs in less than 10 minutes. Patients feel refreshed upon awakening.

Physical and Psychiatric Presenting Symptoms

  • Sleep attacks: Most common symptom.
  • Cataplexy: Pathognomic sign, consisting of a sudden loss of muscle tone which may have been precipitated by a loud noise or intense emotion. If short episode, the patient remains awake.
  • Hypnagogic and hypnopompic hallucinations: Hallucinations that occur as the patient is going to sleep and is waking up from sleep, respectively.
  • Sleep paralysis: Most often occurs during awakening, when the patient is awake but unable to move.
  • Report falling asleep quickly at night.


Forced naps at a regular time of day is usually the treatment of choice. When medications are given, psychostimulants are preferred. If cataplexy is present, antidepressants such as TCAs are preferred.

Sleep Apnea

An overweight man reports having difficulties in his marriage because of his snoring at night. During the day, he reports feeling tired.


A disorder characterized by the cessation of airflow at the nose or mouth during sleep. These apneic episodes usually last longer than 10 seconds each. Characterized by a loud snore followed by a heavy pause. Considered pathologic if the patient has more than 5 episodes an hour or more than 30 episodes during the night. In severe cases, patients may experience more than 300 apneic episodes during the night.

Physical and Psychiatric Presenting Symptoms

  • Usually seen in obese, middle-aged males.
  • Sometimes associated with depression, mood changes, and daytime sleepiness.
  • Spouses typically complain of partner's snoring, and of partner's restlessness during the night
  • Complain of dry mouth in the morning
  • May have headaches in the morning
  • Complain of being tired during the day
  • May develop arrhythmias, hypoxemia, pulmonary hypertension, and sudden death

Types of Sleep Apnea

  • Obstructive: Muscle atonia in oropharynx; nasal, tongue, or tonsil obstruction
  • Central: Lack of respiratory effort
  • Mixed: Central at first, but prolonged due to collapse of the airway


Continuous positive nasal airway pressure is the treatment of choice. Other treatment includes weight loss, surgery.


While studying for an important exam, Michael, a third-year college student, has been unable to sleep for the past several days. At night, he lies awake and imagines himself doing poorly on the exam and failing medical school. During the day, he is tired and frequently falls asleep during his classes.


A disorder characterized by difficulties in initiating or maintaining sleep.

Risk Factors/Epidemiology

Typically associated with some form of anxiety or anticipatory anxiety. Many patients have underlying psychiatric disorders, such as depression, etc. If due to a psychiatric disorder, seen more frequently in women. Other conditions include PTSD, OCD, and eating disorders.

Psychical and Psychiatrical Presenting Symptoms

  • Predominant complaint is difficulty initiating or maintaining sleep.
  • Affects the patient's level of functioning.
  • Frequent yawning and tiredness during the day.


Consider good sleep hygiene techniques, such as arising at same time of the day, avoiding daytime naps, avoiding evening stimulation, discontinuing CNS-acting drugs, taking hot baths near bedtime, eating meals at regular times, using relaxation techniques and maintaining comfortable sleeping conditions. If these do not work, consider behavioral modification techniques such as stimulus control. If medications are to be used, consider benzodiazepines for a short period of time.

Differential Diagnosis

  • Medical: Pain, CNS lesions, endocrine diseases, aging, brain-stem lesions, alcohol, diet, medications.
  • Psychiatric: Anxiety, tension, depression, and environmental changes, other sleep disorders.


Sleep Stage
Nightmares REM Memory of the event upon awakening
Increases during times of stress
Reported by 50% of the population
Usually none indicated, but may use REM suppressants such as TCAs
Night terror Stages 3 and 4 Awakened by scream or intense anxiety
No memory of the event the following day
Seen more frequently in children
More common in boys
Runs in families
Treatment rarely required
If medication is needed, consider benzodiazepines
Sleeptalking All stages of sleep Common in children
Usually involves a few words
May accompany night terrors and sleepwalking

No treatment is necessary

Sleepwalking Stage 3 and 4

Sequence of behaviors without full consciousness
May perform perseverative behaviors
Usually terminates in awakening followed by confusion
May return to sleep without any memory of the event
Begins at a young age
More common in boys
May find neurologic condition
Sleep deprivation may exacerbate

Need to assure patient safety
Use drugs to suppress stages 3 and 4, such as benzodiazepines


1. An overweight man of average height presents to his doctor's office complaining of feeling tired during the day. He has missed several days of work due to this problem. Which of the following is the most likely diagnosis?

  1. Narcolepsy
  2. Insomnia
  3. Sleep apnea
  4. Normal sleep pattern
  5. Hypersomnia

2. Which of the following is the most likely explanation for a young man suddenly falling down but not losing consciousness?

  1. Syncope
  2. Cataplexy
  3. Sleep paralysis
  4. Medication toxicity
  5. Hypotensive episode

3. Which of the following is the treatment of choice for insomnia?

  1. Long-term use of benzodiazepines
  2. Behavioral techniques
  3. Drinking coffee before bedtime
  4. Regular exercises before bedtime
  5. Frequent naps during the day


1. Answer: C. Patients with sleep apnea have multiple episodes of waking up in the middle of the night. Therefore, they are tired during the day. These patients are typically unaware that they wake in the middle of the night.

2. Answer: B. Cataplexy is the sudden loss of muscle tone without loss of consciousness. It is differentiated from syncope in that syncope typically includes loss of consciousness. Patients with narcolepsy are usually young and do not have any blood pressure abnormalities.

3. Answer: B. Although benzodiazepines are regularly used for the treatment of insomnia, the best treatment includes behavioral techniques such as stimulus control. The patient leaves the bed whenever he is unable to fall asleep, therefore conditioning himself that the bed is only used for sleeping. Choices C, D, and E will tend to cause insomnia.

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