Evaluation of Sleep Complaints/Disorders 327out the night. Data are then transferred to a computer for
scoring and analysis. Although a high concordance has been
found between laboratory and home-based polysomno-
graphic data (Ancoli-Israel, 1997; Edinger et al., 1989),
most validation studies have focused on the diagnosis of
sleep-related respiratory disorders. Hence, the validity of
home-based polysomnography in the assessment of insom-
nia has yet to be demonstrated. Despite certain advantages
with home-based polysomnography, there are other disad-
vantages such as the risk of artifacts and the invalidation
of records (there is no technician to correct problems that
may arise during the night) and the lack of behavioral
observations from technicians (making interpretation more
dif“cult in some cases).
Self-Report Measures
There is a wide variety of self-report questionnaires that
are available to assess insomnia. Some of these instruments
are designed as general screening measures of sleep quality or
sleep satisfaction, others are intended to evaluate the sever-
ity/impact of insomnia, and still others focus on presumed me-
diating factors of insomnia. Because of the large number of
such measures, only a sample of those most widely used in re-
search and clinical practice is described here.
The Pittsburgh Sleep Quality Index (PSQI)
The PSQI (Buysse, Reynolds, Monk, Berman, & Kupfer,
1989) is a self-rating scale frequently used to assess general
sleep disturbances. The PSQI is composed of 19 self-rated
items assessing sleep quality and disturbances over a one-
month interval. It covers subjective sleep quality, sleep la-
tency, sleep duration, sleep ef“ciency, sleep disturbances, use
of sleeping medication, and daytime dysfunction. A summa-
tion of these seven component scores yields a global score of
sleep quality ranging from 0 to 21. The “rst four items are
open-ended questions, while the remaining items are rated on
a Likert scale ranging from 0 to 3.
The Sleep Impairment Index (SII)
The SII (Morin, 1993) yields a quantitative index of insom-
nia severity. The SII is composed of seven items assessing,
on a “ve-point scale, the perceived severity of problems
with sleep onset, sleep maintenance, and early morning
awakenings, the satisfaction with the current sleep pattern,
the degree of interference with daily functioning, the no-
ticeability of impairment due to the sleep disturbance,
and the degree of worry or concern caused by the sleep
problem. The total SII score, obtained by summing the
seven ratings, ranges from 0 to 28. A higher score indicates
more severe insomnia. The SII takes less than “ve minutes
to complete and score. Two parallel versions, provided by a
clinician and a signi“cant other (e.g., spouse, roommate),
are available to provide collateral validation of patients•
perceptions of their sleep dif“culties (Bastien, Vallières,
Morin, 2001).The Dysfunctional Beliefs and Attitudes about
Sleep Scale (DBAS)The DBAS (Morin, 1994) is a 30-item self-report scale de-
signed to assess sleep-related beliefs and attitudes that are be-
lieved to be instrumental in maintaining sleep dif“culties
(Morin, 1993). The patient indicates the extent of agreement
or disagreement with each statement on a visual analogue
scale ranging from 0 (strongly disagree) to 100 (strongly
agree). Ratings are summed to yield a total score; a higher
score suggests more dysfunctional beliefs and attitudes about
sleep. The content of the items re”ects several themes such as
faulty causal attributions (e.g., •I feel that insomnia is basi-
cally the result of agingŽ), ampli“cation of the perceived
consequences of insomnia (e.g., •I am concerned that chronic
insomnia may have serious consequences for my physical
healthŽ), unrealistic sleep expectations (e.g., •I need eight
hours of sleep to feel refreshed and function well during the
dayŽ), diminished perception of control and predictability of
sleep (e.g., •I am worried that I may lose control over my
abilities to sleepŽ), and faulty beliefs about sleep-promoting
practices (e.g., •When I have trouble getting to sleep, I
should stay in bed and try harderŽ). The DBAS is particularly
useful for clinicians in identifying relevant targets for cogni-
tive therapy.
Self-report measures offer several practical and economi-
cal advantages. They can easily be used in a variety of con-
texts to provide a global assessment of sleep dif“culties, and
they can be administered repeatedly to measure therapeutic
changes. The main limitation is their retrospective nature and
the associated risk of recall biases. Typically, insomnia is pre-
sent only some nights in a given week, even in individuals
with chronic insomnia. Also, the severity of sleep dif“culties
can vary considerably from night to night, which makes it
dif“cult for the individual to retrospectively give precise
information on these variables. Because individuals with in-
somnia are often distressed by their sleep dif“culties, they
tend to recall and generalize from those nights that were
most disturbed, resulting in an overestimation of insomnia.
Despite these limitations, self-report scales remain very cost-
effective methods for initial assessment and treatment
outcome evaluation.