Sleep. 15(1):71-73
© 1992 American Sleep Disorders Association and Sleep Research Society
Subjective Total Insomnia: An Example of
Sleep State Misperception
W. Vaughn McCall and Jack D. Edinger
VA Medical Center/Duke University Medical Center, Durham, North Carolina, U.S.A.
Summary: Sleep state misperception (SSM) is the diagnostic term proposed in the International Classification of
Sleep Disorders to describe those insomniacs who mislabel their sleep as wakefulness. Although sleep misperception
has long been recognized among insomnia patients, it is debatable whether this clinical finding warrants a distinctive
diagnosis or simply represents an extreme variation of other, more common forms of insomnia. We present two
cases to explore the clinical meaningfulness of SSM. It is concluded that SSM represents a distinctive, albeit rare,
sleep disorder. However, refinements in existing diagnostic criteria may be needed to improve the meaningfulness
of the SSM diagnosis. Key Words: Sleep state misperception-Insomnia patients.
Sleep state misperception (SSM) is the current diagnostic term reserved for the small and perplexing
group of insomnia patients who appear unable to discriminate sleep from wakefulness. This diagnosis is
assigned to psychiatrically and medically healthy patients complaining of persistent insomnia in the absence of objective [polysomnographic (PSG)] evidence
confirming sleep disturbance. Current diagnostic criteria (1) for this condition require that (a) the patient
has a complaint of insomnia; (b) the sleep duration
and quality are normal; (c) PSG demonstrates normal
sleep latency, a normal number of arousals, and normal
sleep duration; (d) an absence of any medical or psychiatric disorder that can produce the complaint; and
(3) other sleep disorders producing insomnia are not
present to the degree that would explain the patient's
complaint. Despite these criteria, sleep experts have
long disagreed about whether these patients represent
a distinctive disorder or merely are an extreme variation of other, more common forms of intrinsic insomnia.
Evidence suggesting that SSM represents a distinctive form of sleep pathology comes both from the research and the clinical literature. Comparisons of subgroups using an auditory vigilance task suggest that
SSM patients have much greater impairment of daytime vigilance than do other insomnia subgroups or
normal controls (2). Similarly, SSM patients have been
shown to have more restless sleep as measured by wrist
actigraphy than do other insomnia subtypes (3).
Despite this evidence, the meaningfulness of SSM
as a distinctive diagnostic category has been criticized
on both empirical and conceptual grounds. As noted
by several authors, inaccurate estimates of total sleep
time and sleep latency are common to all forms of
insomnia, not just in one specific subgroup (4-7). Further, the sleep of insomnia patients in general is characterized by marked night-to-night variability; typically several nights of poor sleep are followed by one
or more nights of sleep recovery (7-9). As a result,
clinicians are likely to "capture" a good night's sleep
on a PSG even when evaluating a patient with genuine
insomnia. Because many sleep centers rely on a single
diagnostic PSG study, patients with genuine sleep disturbance risk erroneous assignment of an SSM diagnosis if this study misrepresents their usual sleep pattern. Further, as noted by Trinder (7), there is little
evidence to suggest that patients' perceptions of sleep
during a PSG are at all similar to their subjective sleep
experiences in their home environments.
In view of these criticisms it remains questionable
whether SSM represents a meaningful diagnostic label.
In particular, it is debatable whether it is descriptively
or prognostically useful to assign an SSM diagnosis to
those patients who grossly under-report sleep on the
night of a single PSG study. Since 1989 we have evaluated two cases of subjective total insomnia who approximate current criteria for SSM. We present these
extreme cases to highlight the clinical relevance of the
Accepted for publication September 1991.
Address correspondence and reprint requests to W. Vaughn McCall,
Dept. of Psychiatry, Bowman Gray School of Medicine, 300 S. Hawthorne Rd., Winston-Salem, NC 27103, U.S.A.
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72
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V. McCALL AND J. D. EDINGER
diagnosis and to describe shortcomings of the current chronicity of the complaint but noted that he believed
diagnostic criteria for SSM.
her to have normal sleep. Her psychiatric history and
mental status examination were without suggestion of
psychiatric illness. Moreover, her MMPI scales were
METHODS
all well within normal limits. Her PSG showed a 26Both cases were outpatients whose subjective sleep minute sleep onset latency, 411 minutes of sleep, 82
estimates disagreed markedly from objective sleep re- minutes of WASO and otherwise normal sleep archicordings. Evaluation for these cases included a psy- tecture without signs of apnea or periodic limb movechiatric interview, a thorough sleep problem history, ments. Despite these findings, she reported no sleep
a physical examination, the Minnesota multiphasic on the PSG night and did not believe the PSG results.
personality index (MMPI), 14 days of sleep diaries and The patient was unable to comply with the subsequent
one night of PSG. All sleep studies were conducted recommended stimulus control and sleep restriction
using ambulatory cassette PSG. We and others have treatment because of her inability to perceive sleepidocumented that this PSG method produces reliable ness.
and useful sleep data and is well tolerated by subjects
(10-13). The monitoring montage consisted of two
DISCUSSION
electroencephalographic (EEG) channels (C3-M2, OzThese two cases demonstrate extreme examples of
Cz), two channels of an electrooculograph (EOG), chin
electromyograph (EM G), bilateral tibialis EMG and patients who might be assigned the diagnosis of SSM.
oraVnasal thermistor. The patients underwent elec- Both patients had longstanding complaints of subjectrode attachment between 12: 30 and 16: 30 in the sleep tive total insomnia, supportive sleep diaries, absence
laboratory but were allowed to sleep in their own homes of gross psychiatric pathology and essentially normal
on the PSG night. On awakening in the morning, the PSGs on nights they continued to complain of total
patients completed a standard sleep diary to provide insomnia. In addition to meeting the spirit of the ditheir subjective impressions oftheir sleep on the study agnostic criteria for SSM (1), these patients withstand
the critics' (6,7) typical challenges to the validity of
night.
this diagnosis. Because the total insomnia complaints
were unrelenting in these patients it could not be argued
CASES
that PSG studies were not representative because they
were conducted during a phase of good sleep. MoreCase 1
over, the total insomnia complaint was so extreme and
This 28-year-old man complained of receiving 0-1 so central to these cases as to distinguish them from
hours of sleep per night for the 4.5-year period prior other types of insomniacs who typically present far less
to evaluation. Fourteen day's worth of sleep diaries dramatic misperceptions of their sleep (4,5). Finally,
showed no sleep on 12 nights and 1 hour of sleep on although it is possible these cases experienced worse
each of the remaining 2 nights. Psychiatric history and sleep on nonPSG nights, it is physiologically improbmental status exam were unremarkable for major psy- able that they were totally without sleep for the duchiatric disturbance. His MMPI did not suggest major ration of their complaints. Indeed, the unrelenting napsychopathology. The PSG displayed a sleep latency ture of their subjective complaints across PSG and
of 27 minutes, 433 minutes of sleep, 17 minutes of nonPSG nights suggests a marked subjective-objective
wakefulness after sleep onset (WASO), normal sleep sleep discrepancy was likely on nights these patients
architecture and no signs of apnea or periodic limb were not monitored. The difficulty in prescribing stanmovements. Nevertheless, the patient reported "no dard behavioral treatment for these patients seemed
sleep as usual" on his study night. Subsequent treat- related to their inability to identify sleepiness and folment with combined stimulus control and sleep re- low rules such as "go to bed only when sleepy." This
striction behavioral therapy produced little improve- treatment obstacle may be a factor in favor of distinment.
guishing SSM as a diagnosis with features separable
from other primary insomnias.
The clinical characteristics and marked discrepancy
Case 2
between objective and subjective sleep on the night of
This 39-year-old woman complained of 13 years of PSG for cases 1 and 2 were fundamentally the same.
total sleeplessness. She reported no daytime naps and The failure of case 2 to satisfy strict current SSM crino sleep at any time during this 13-year period. Fur- teria (she had 82 minutes of WASO) highlights the
ther, she denied sleepiness or the ability to sleep during problems inherent in relying too heavily on PSG data
the daytime. Her husband of 3 years confirmed the in making the diagnosis. These cases suggest an alterSleep, Vol. 15, No.1, 1992
73
TOTAL INSOMNIA
native approach is needed in making the SSM diagnosis. Current criteria for SSM start with the discovery
of a discrepancy between subjective and PSG sleep and
then work backward to the diagnosis. Herein lies the
weakness of that diagnostic approach and the source
of challenges to the SSM diagnosis. Most other sleep
disorders start with a suspicion generated by the complaint and clinical history. Sleep apnea is suspected on
the basis of snoring and excessive daytime sleepiness
(EDS) whereas narcolepsy is suspected by the complaints of EDS and cataplexy. PSG and other laboratory tests are then used to support or refute these initial
clinical impressions.
We suggest that SSM would be more meaningful if
its diagnosis followed the same order of logic as that
required for other sleep disorders. Specifically, a probable diagnosis of SSM should be predicated on the
presentation of a complaint that is physiologically improbable (i.e. unrelenting total insomnia) and suggests
an extreme misperception of the sleep state. A subsequent discrepancy between PSG recorded sleep and
subjective sleep would, in tum, conclusively confirm
the clinical impression. An SSM diagnosis made in
this manner would be meaningful in describing the
patient's insomnia, not only on the PSG night, but
throughout the duration of the complaint.
From this perspective, SSM is neither a nonexistent
"pseudodiagnosis" (7) nor a highly prevalent condition
diagnosed in as many as 25% of all the insomnia patients seen at some sleep centers (14). This report presents the only two such cases we identified among the
190 insomnia patients we have seen in the last 2 years.
We chose these cases because the complaint of total
insomnia facilitated discussion of the meaningfulness
of SSM. Other patients with less dramatic complaints
may also represent SSM, but they may be more difficult
to discriminate from the majority of insomniacs who
make smaller errors in sleep estimation. Moving away
from primarily a PSG-based diagnosis to a diagnosis
rooted in the clinical history opens the possibility of a
probable diagnosis of SSM being entertained by cli-
nicians lacking immediate access to a sleep laboratory.
Thus, rather than remaining a passing curiosity found
only in the province of polysomnographers, SSM can
be viewed as a diagnosis worthy of consideration by
all clinicians who encounter insomnia patients.
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Sleep, Vol. 15, No.1, 1992