Insomnia and Anxiety (Series in Anxiety and Related Disorders) (5 page)

patient sleeping in a laboratory with various wires coming out of his or her head.

Indeed, a polysomnogram (PSG) involves sleeping overnight in a laboratory, while

electroencephalogram (EEG), electrocardiogram (EKG), pulse oximetry, air flow

and electromyogram (EMG) equipment monitor brain, heart, respiration, and

muscle activity, respectively. While it is often assumed that overnight PSG studies

are used to assess insomnia, the measurement of insomnia most typically involves

structured or unstructured interviews and self-report instrumentation. In fact, the

standards in the field dictate that polysomnography (PSG) should not be used in

routine assessment for insomnia (American Sleep Disorders Association, 1995).

C.E. Carney and J.D. Edinger,
Insomnia and Anxiety
, Series in Anxiety and Related Disorders,

13

DOI 10.1007/978-1-4419-1434-7_2, © Springer Science+Business Media, LLC 2010

14

2 Considerations for Assessment

Among the reasons for not using PSG is the fact that many people with insomnia

will simply sleep very little – which is expensive verification for what they have

already reported (i.e., they have difficulty sleeping). Alternatively, the opposite can

occur as well. That is, some people experience what is called the “first-night effect,”

and they sleep considerably better than usual. The presumed mechanism of the

first-night effect is conditioning. Those with psychophysiological insomnia fre-

quently evidence conditioned arousal in their bed/bedroom, and the change in set-

ting no longer elicits arousal during the sleep period. Thus, traditional PSG,

clinically speaking, often tells us little about the person with insomnia. The excep-

tion to this is that some people with insomnia actually have another occult sleep

disorder, such as sleep apnea, that would better account for their symptoms, and

this could only be detected by the PSG.

In contrast to clinical practice, research using the PSG has revealed much about

the sleep of those with insomnia. PSG data is used to visually score and classify 30 s

periods called epochs into various stages of sleep or wakefulness, as well as to

denote whether there was a significant event (e.g., a period in which the brain roused

out of sleep). This is done according to accepted scoring criteria (Rechtshaffen &

Kales, 1968). In insomnia, not all insomnia sufferers have disturbed sleep according

to these scoring principles. In fact, there can be a discrepancy of minutes to hours

between the sleep reported by people with insomnia and what is seen on the PSG.

This is generally the exception to the rule and in some cases may be a subtype of

insomnia called paradoxical insomnia. In paradoxical insomnia there is a large dis-

crepancy between objective recordings of sleep and the subjective report of little to

no sleep. In addition, the daytime impairment is far less than you would expect given

their dramatic reports of sleep loss. Setting those with paradoxical insomnia aside,

there can be some discrepancy between objective and subjective sleep. Some of this

may have to do more with our measurement than with an insomnia sufferer neces-

sarily making a perceptual error. The visual scoring method can obscure relative

range and amplitudes of each band of electrical brain activity during sleep stages, as

well as brief, frequent sleep stage transitions. Thus, it seems reasonable to assume

that subjectively important sleep information is not captured by the traditional PSG

scoring approach. In contrast, sleep EEG spectral analysis provides a microarchitec-

tural picture of brain wave activity across sleep stages. Applications of such analyses

to the study of insomnia have been promising and suggested that spectral measures

effectively discriminate psychophysiological insomnia sufferers from normal sleep-

ers and other insomnia subtypes (Freedman, 1986; Lamarche & Ogilvie, 1997;

Nofzinger et al., 1999; Perlis, Smith, Andrew, Orff, & Giles, 2001). Perlis et al.

(2001) have shown that the degree of relative power in the Beta (14–35 Hz) range

negatively correlates with subjective–objective discrepancy measures for sleep time

and sleep onset latency. This finding seems particularly intriguing since it implies

that EEG spectral indices may relate to subjective insomnia sufferers’ complaints. It

should be noted that little has been done with spectral analysis and anxiety disorders,

so much of what we will report will be nonspectral polysomnographic findings only.

As such, mixed or absent findings using visually scored methods may not necessar-

ily imply that the sleep disturbance is only subjective.

Subjective Assessment of Sleep

15

Actigraphic Measurement of Sleep

The most commonly known objective measure of sleep is the polysomnogram, but

a less expensive and commonly used measure is actigraphy. An actigraph is a small,

wrist-watch-like instrument that detects movement using an accelerometer. Scoring

algorithms can then determine whether the activity is indicative of sleep or wake-

fulness. Measures of movements during sleep provide a relatively inexpensive,

objective assessment of several sleep parameters, as well as objective corroboration

of the subjective, self-report sleep evaluations obtained from sleep logs. Actigraphic

monitoring is widely used as an objective estimate of sleep variables in insomnia

research given that sleep parameters derived from actigraphs correlate well with

PSG derived variables.

Subjective Assessment of Sleep

When someone with insomnia presents for treatment, she/he usually has ready

answers for the clinically important questions such as:

“What time do you go to bed?”

“What time do you get up in the morning?”

“How long does it take you to fall asleep?”

“How long are you awake during the night?”

Whereas some people are able to provide reasonably accurate answers to these

questions, a substantial proportion of insomnia sufferers provide answers that do not

provide an accurate portrayal of their general sleep difficulty and usual sleep prac-

tices. This is usually not due to an intention to exaggerate the sleep difficulty or

otherwise provide any misleading information. Moreover, it results from a natural

tendency to remember the more difficult nights that led to seeking professional

consultation. Moreover, sleep habits and sleep patterns are notoriously variable from

one night to the next among insomnia sufferers, so the summary retrospective apprais-

als required by the questions shown are likely to overlook this variability, and thus

conceal important treatment targets. For this reason, the evaluation of insomnia

usually benefits by prospective assessment techniques fashioned to capture the sleep

and associated behavioral variability that defines the insomnia disorder. The tool most

commonly used for this purpose is the sleep diary. Rather than asking if particular

sleep behaviors are a problem, sleep logs generally inquire about how long it took

to fall asleep and the time spent awake in the middle of the night (see Fig. 2.1).

We discuss face-valid retrospective measures of symptom severity later in the chapter.

In its usual format, the sleep diary is a paper and pencil instrument designed

to allow the collection of information about sleep patterns prospectively over a

period of several weeks. The typical sleep diary includes questions about

16

2 Considerations for Assessment

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Subjective Assessment of Sleep

17

nightly bed time and rising time, the perceived time it takes to fall asleep each

night, the amount of time being awake during the night, and the time of the final

morning awakening. Also, often included are questions about the quality of

each night’s sleep, daytime napping patterns, and usage of substances (caffeine,

alcohol, sleep medications) that might influence sleep each night. Sleep diaries

are useful for quantifying insomnia severity, aiding in diagnostic discrimina-

tions and case conceptualization, guiding the implementation of behavioral

interventions, and measuring treatment outcomes (Buysse, Ancoli-Israel,

Edinger, Lichstein, & Morin, 2006). Indeed, the sleep diary is such a mainstay

of behavioral insomnia treatment that it is difficult to envision implementing

treatment strategies such as those described later in this chapter without this

invaluable tool.

A variety of paper and pencil sleep diaries are available, and these differ

slightly in the type or amount of information obtained (Edinger & Carney, 2008;

Espie, 2000; Monk et al., 1994; Morin, 1993; Sateia, 2002; Wohlgemuth &

Edinger, 2000). Figure 2.1 shows one version commonly used in insomnia treat-

ment studies and in clinical venues. Through the daily entries this type of diary

elicits, daily bedtimes, rise times and napping patterns can be ascertained, and

estimates of nightly sleep and wake time can be derived. Whereas this type of

diary adapts well to the assessment of many types of insomnia problems, alternate

versions may better suit the needs of certain populations or certain types of sleep

difficulties. For example, The National Sleep Foundation has developed three

sleep diary versions geared toward adults, teenagers, and children (NSF, 2007).

The American Academy of Sleep Medicine [www.aasm.org] offers a diary that is

structured in an analogue design (AASM, 2008) that instructs respondents to

“color in” the blocks of time slept. This type of diary may provide a richer picture

of sleep patterns for individuals who have difficulty accurately completing the

traditional diary or among those who have erratic sleep patterns (e.g., shift work-

ers). Nonetheless, the format shown in Fig. 2.1 is used in this chapter since it is

well suited for initial assessment and tracking response to the types of treatment

discussed later.

Thus, with sleep diaries, the clinician can determine whether particular sleep

indices like sleep onset latency is a problem based on norms. For example, if some-

one complains that they cannot sleep on a fairly consistent basis, and their logs

support this complaint, they are viewed as having subjectively disturbed sleep. How

well do people estimate their sleep? This is a tricky proposition as it begs the ques-

tions, what should be the gold standard for comparison? If insomnia is a subjective

disorder, should not subjective report be the gold standard? Generally speaking,

people do fairly well in estimating their sleep when compared to an objective mea-

sure such as polysomnography. The most common
errors
when compared with