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Chapter 15: Sleep-Wake Disorders

INTRODUCTION

Sleep disorders affect as many as 40% of the U.S. adult population. Current data demonstrate a high rate of comorbidity between sleep disorders and various psychiatric illnesses. Disturbances in sleep can potentiate and/or exacerbate psychological distress and other mental illnesses.

NORMAL SLEEP-WAKE CYCLE

  • Normal sleep-wake cycle is defined in terms of characteristic changes in several physiological parameters, including brain wave activity, eye movements, and motor activity.

  • The two stages of normal sleep are rapid eye movement (REM) sleep and non-rapid eye movement (NREM) sleep.

  • About every 90 minutes, NREM sleep alternates with REM sleep.

  • NREM induces transition from the waking state to deep sleep.

  • Progression through NREM sleep results in slower brain wave patterns and higher arousal thresholds.

  • In REM sleep, brain wave patterns resemble the electroencephalogram (EEG) of an aroused person.

  • Awakening from REM sleep is associated with vivid dream recall. See Figure 15-1.

FIGURE 15-1.

The sleep cycle. © 2008 LLS. Adapted, with permission of the publisher, Les Laboratoires Servier, from Figure 1 in Nutt D, Wilson S, Paterson L. Sleep disorders as core symptoms of depression. Dialogues Clin Neurosci. 2008;10(3):329–336.

A sleep cycle graph has indications of awake, movement, R E M sleep, and stages 1 to 4 of Non R E M sleep on the vertical axis and hours on the horizontal axis
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image   KEY FACT

As one ages there are the following changes that occur in the sleep pattern:

  • Increase in time it takes to fall asleep, known as sleep latency

  • Decline in total amount of REM sleep achieved

  • Increase in sleep fragmentation with more frequent nighttime awakening

SLEEP DISORDERS

  • Classified as either:

    • Dyssomnias: Insufficient, excessive, or altered timing of sleep.

    • Parasomnias: Unusual sleep-related behaviors.

  • When taking a sleep history, ask about:

    • Activities prior to bedtime that may interfere with restful sleep.

    • Bed partner history.

    • Consequence on waking function; quality of life.

    • Drug regimen, medications.

    • Exacerbating or relieving factors.

    • Frequency and duration.

    • Genetic factors or family history.

    • Habits (alcohol consumption, use of caffeine, nicotine, illicit substances, and hypnotics).

DYSSOMNIAS

Dyssomnias are disorders that make it difficult to fall or remain asleep (insomnias), or cause excessive daytime sleeping (hypersomnias).

image   WARDS TIP

REM sleep is characterized by increase in blood pressure, heart rate, and respiratory rate.

Insomnia Disorder

  • Refers to a number of symptoms that interfere with duration and/or quality of sleep despite adequate opportunity for sleep. Symptoms may include:

    • Difficulty initiating sleep (initial or sleep-onset insomnia).

    • Difficulty maintaining sleep (middle or sleep-maintenance insomnia).

    • Early morning awakenings (late or sleep-offset insomnia).

    • Waking up feeling fatigued and unrefreshed (nonrestorative sleep).

  • Acute insomnia (less than 3 months) is generally associated with stress or changes in sleep schedule and usually resolves spontaneously.

  • Chronic insomnia lasts greater than or equal to 3 months to years and is associated ...

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