Evidence Report/Technology Assessment: Number 125
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Introduction / Methods / Main Results / Discussion / Conclusions / Availability of Full Report / References
Authors: Buscemi N, Vandermeer B, Friesen C, Bialy L, Tubman M, Ospina M,
Klassen TP, Witmans M.
Prevalence of Insomnia
Insomnia, or inability to sleep, is the most
commonly reported sleep problem in the
industrialized world.1 Estimates suggest that
between 40 and 70 million Americans are
affected by either intermittent or chronic sleep
problems, representing approximately 20 percent
of the population.2 The Sleep in America Poll,
conducted by the National Sleep Foundation,
revealed that almost 50 percent of people
surveyed had complaints of frequent insomnia,
but only 6 percent were formally diagnosed.3
Moreover, approximately, 30 to 35 percent of
respondents complained of nightly insomnia.3
The most prevalent symptoms of insomnia,
experienced at least a few nights a week by
people with insomnia, include waking up feeling
unrefreshed (34 percent) and being awake often
during the night (32 percent).3 The symptoms
of difficulty falling asleep and waking up too
early are less common, but still experienced at
least a few nights a week by about one-fourth of
adults with insomnia (23 to 24 percent).3
Risk Factors for Insomnia
Although some risk factors and etiologies of
insomnia have been identified, the nature of the
relationships has not been fully elucidated. Some
risk factors for insomnia that have emerged from
data related to insomnia include female gender3
and old age.4 Additional risks factors include less
education, unemployment, separation or divorce,
and medical illness.1
Insomnia may be primary
or secondary to other sleep problems and may be
associated with a number of co-morbidities. An
association has been found between insomnia
and psychiatric (depression and anxiety) and
psychological disorders.4 There is increasing
evidence that chronic insomnia may predispose
individuals to the development of psychiatric
Persistent insomnia increases the risk
of depression, substance abuse, and anxiety
disorders. Environmental factors such as
irregular sleep schedules, use of caffeine or other
stimulants, co-morbid medical conditions,
and/or shift work may also predispose vulnerable
individuals to insomnia.
Consequences of Insomnia
Insomnia has significant direct and indirect
effects on the health and wellness of affected
individuals. Insomnia has been correlated with
frequent use of medical services,7-8 chronic health
problems,9-10 increased drug use,7-8 and perceived
poor health,11 and has been associated with
medical problems including heart disease,12
hypertension,13 and musculoskeletal problems.12
The daytime consequences of chronic insomnia
often include increased healthcare utilization,
increased risk of depression,14 poor memory,
reduced concentration, poor work performance,
and perceived or real risk of failure at work.15
The economic implications of insomnia and associated morbidity have been described.7,3 The direct costs of
insomnia (insomnia treatments, healthcare services, hospital
and nursing home care) are estimated to be nearly $14
billion.16-17 The indirect costs of insomnia, such as time lost
from work and loss of productivity, are estimated to be nearly
$28 billion. A National Sleep Foundation survey found that
lost productivity from insomnia alone was over $18 billion.
Management of Insomnia
Management of acute insomnia has traditionally involved
pharmacotherapy. The use of such agents is common practice
for both acute and chronic insomnia, despite the fact that the
Food and Drug Administration (FDA) has approved none of
them for chronic insomnia. Another medication, eszopiclone
(Lunesta), was recently approved by the FDA for treatment of
insomnia, but the duration of use is not explicitly stated. An
estimated 0.5 percent of the population takes sedative
medications for insomnia for more than 1 year.3 More than 1
in 10 people (11 percent) report using prescription (6 percent)
and/or over-the-counter (OTC) medications (6 percent), at
least a few nights a month, to help them sleep, according to a
Sleep in America Poll.3
Individuals reporting symptoms of
medical conditions are more likely to take sleep aids, both
prescription and OTC medications. For example, 14 percent
of people with symptoms of depression report using
prescription medication, and 12 percent of people with
symptoms of depression report using OTC sleep aids.3
Medications commonly used to treat insomnia include
sedating antidepressants,18 antihistamines, anticholinergics,
benzodiazepines, and non-benzodiazepine hypnotics. A side
effect of all hypnotics is to reduce slow wave sleep. Other side
effects of concern are possible daytime residual effects related
to sedation, rebound insomnia, and tolerance, along with
minor side effects specific to each drug class. Many questions
and challenges related to pharmacological therapy for chronic
insomnia remains, such as the appropriate treatment for
different types of primary and secondary insomnia, and the
long-term side effects and daytime consequences of
pharmacotherapy. The evidence for management of chronic
insomnia with pharmacotherapy has not been systematically
Cognitive/behavioral therapy has been recognized as a valid
and successful treatment approach for insomnia. Cognitive/behavioral therapy can include any combination of sleep
restriction, sleep hygiene, stimulus control, paradoxical
intention, and cognitive restructuring. Many of these
commonly used clinical tools have not undergone rigorous
testing to determine their efficacy and long-term safety. The
efficacy of these treatments has been evaluated in some
studies,4,19 but differences in the definition of insomnia and
outcome measures make it difficult to compare study results.
In summary, insomnia is a common complaint with
significant consequences. Significant advancements have been
made in sleep research over the past three decades, yet many
questions related to the treatment of chronic insomnia remain.
Our goal was to review the evidence and state of research in
the area of chronic insomnia.
The objectives of this report are to conduct a systematic
- The prevalence, natural history, incidence, risk factors, and consequences of chronic insomnia in adults.
- The efficacy and safety of treatments used in the management of chronic insomnia in adults.
A population was
considered to suffer from chronic insomnia if the sleep
disturbance persisted for at least 4 weeks, regardless of severity
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The research librarian, in collaboration with the TEP
(Technical Expert Panel), developed and implemented search
strategies designed to identify relevant evidence for key
questions of the review. A systematic search of 21 electronic
databases was conducted. We searched MEDLINE®,
EMBASE, CINAHL®, Ovid MEDLINE® In-Process &
Other Non-Indexed Citations, Ovid OLDMEDLINE®,
PsycINFO®, EBM Reviews-Cochrane Central Register of
Controlled Trials, International Pharmaceutical Abstracts,
AMED (Allied and Complementary Medicine),
HealthSTAR/Ovid Healthstar, EBM Reviews-Cochrane
Database of Systematic Reviews (CDSR), ACP Journal Club
(ACPJC), Database of Abstracts of Reviews of Effects
(DARE), Science Citation Index Expanded™, Biological
Abstracts, Cochrane Complementary Medicine Field Registry,
CAB Abstracts, SIGLE, OCLC Proceedings First, Dissertation
Abstracts, Alt HealthWatch, NLM Gateway, and PubMed®.
Most of the searches were limited to humans, and no age
restrictions were applied to any of the searches.
For Question 1, which relates to the definition,
classification, diagnosis, and aetiology of chronic insomnia in
adults, we searched for narrative and systematic reviews, book chapters, diagnostic manuals and standards of practice
parameters, and applied English-language restrictions.
Question 2, which relates to the prevalence, natural history,
incidence, and risk factors for chronic insomnia in adults, and
Question 3, which relates to the consequences, morbidities,
co-morbidities and public health burden associated with
chronic insomnia in adults, we searched for observational
studies, encompassing a range of designs including cross-sectional,
case-control, and cohort studies, and applied
For Question 4, which relates to
the treatments for chronic insomnia in adults, and the
evidence regarding their safety, efficacy, and effectiveness, we
searched for randomized controlled trials, and no language
restrictions were applied.
We did not develop formal inclusion criteria for the
question pertaining to the definition, classification, diagnosis,
and etiology of chronic insomnia (Question 1), nor for the
question pertaining to the future direction of insomnia-related
research (Question 5). The former question was answered by
providing an overview of the literature, and the latter question
was answered by assessing the limitations in the evidence for
the other questions of the review.
Inclusion criteria were developed for three questions of the
review (Questions 2-4). Question-specific inclusion criteria
appear below. In the interest of clarity, questions 2 and 3 will
be referred to as the questions on manifestations of chronic
insomnia, while question 4 will be referred to as the question
on management of chronic insomnia.
2. What are the prevalence, natural history, incidence,
and risk factors for chronic insomnia?
factors of interest include age, gender, race/ethnicity,
psychiatric illness and psychological problems, medical
disease, socioeconomic status, and shift work.
A study was considered to be relevant to the portion of
Question 2 pertaining to the prevalence, natural history, and
incidence of chronic insomnia, if it met the following criteria:
- The report was written in English.
- Participants were at least 15 years old.
- It examined chronic insomnia.
- It had a cross-sectional or cohort design.
- It assessed the prevalence, natural history, or incidence of chronic insomnia.
A study was considered to be relevant to the portion of
Question 2 pertaining to risk factors for chronic insomnia, if it
met the first three criteria listed above as well as the following:
- It had a cohort, case-control, or cross-sectional design.
- It assessed one of the risk factors of interest.
3. What are the consequences, morbidities, comorbidities,
and public health burden associated with
Specific outcomes of interest include
healthcare utilization, psychiatric illness, absenteeism,
work performance, accidents, falls in the elderly, quality
of life and social relationships, memory, cognitive
function, mood, and direct and indirect costs.
A study was considered to be relevant to this question of the
review, if it met the first three criteria outlined for Question 2 as
well as the following:
- It had a cohort or cross-sectional design.
- It assessed one of the consequences of interest.
For Questions 2 and 3, a study was considered to examine
chronic insomnia if this condition was defined as a sleep
disturbance of four weeks or more or the report explicitly
mentioned that chronic sleep disturbance was examined.
4. What treatments are used for the management of
chronic insomnia and what is the evidence regarding
their safety, efficacy, and effectiveness?
treatments of interest include prescription medication,
over-the-counter medication, alcohol, behavioral therapy,
combination therapy, and complementary and alternative
A study was considered to be relevant to this question of the
review, if it met the following criteria:
- The report was written in English.
- Participants were at least 15 years old, and the majority were at least 18 years old.
- Participants suffered from chronic insomnia.
- Participants were randomized to intervention or placebo.
- Participants and assessors were blind to treatment received.
- It assessed at least one of the following outcomes, listed in order of importance in deriving conclusions of the review:
- Sleep onset latency.
- Wakefulness after sleep onset.
- Sleep efficiency.
- Total sleep time sleep quality.
- Quality of life.
Sleep onset latency was defined as the amount of time
between the participant laying down to sleep and the onset of
sleep; wakefulness after sleep onset was defined as the amount
of time spent awake in bed following the attainment of sleep;
sleep efficiency was defined as the amount of time spent asleep
as a percentage of the total time spent in bed; and total sleep
time was defined as the total time spent asleep while in bed.
Sleep onset latency and wakefulness after sleep onset were
given the highest priority in deriving conclusions from the
review, since they were considered the best indices of sleep
initiation and sleep maintenance, respectively. However,
subgroup analyses were conducted only on data relevant to
sleep onset latency, since this outcome was the most highly
reported outcome across studies.
If the majority of participants met one of the following
criteria, the study population was considered to suffer from
- Participants suffered from a sleep disturbance of four weeks or more.
- Participants were described as having a chronic/long-standing/persistent sleep disturbance.
- Participants were selected from a sleep disorders clinic.
In the case of combination therapy, the combined treatment
could be compared to either placebo or single treatment.
We acknowledged the fact that double-blinding is often not
feasible in studies of psychological treatments by not requiring
double-blinding in these studies for inclusion in the review.
The placebo treatment for relaxation therapy and cognitive/behavioral therapy was minimal treatment, such as sleep
hygiene recommendations or minimal instruction. We
required that the placebo resemble the intervention of the
study except that it was known to produce either no effect or
only a minimal effect.
In the first stage of study selection, two reviewers screened
the titles and abstracts of all potentially relevant articles,
independently. Each reviewer noted the titles and abstracts
that were potentially relevant to the review, and these articles
were retrieved. In the second stage of study selection, two
reviewers appraised the potentially relevant articles,
independently, using pre-determined, question-specific,
inclusion criteria. Disagreements between reviewers were
resolved by discussion and consensus. The rate of
disagreement between reviewers and the primary reason for
exclusion of potentially relevant articles were noted.
Data relevant to study design, population, interventions,
and outcomes were extracted from studies, as appropriate,
using standardized data extraction forms. A trained reviewer
extracted relevant data, and a second reviewer verified the data
extracted for accuracy and completeness.
Assessment of Study Quality
The quality of studies relevant to the questions on
manifestations of chronic insomnia was assessed using one of
three instruments; studies on prevalence and incidence were
assessed using a scale designed specifically for this purpose.20
All other studies relevant to manifestations of chronic
insomnia were assessed using one of two Newcastle-Ottawa
scales (unpublished), each scale specific to either cohort or
The quality of studies relevant to management of chronic
insomnia was assessed using the Jadad scale.21 The
concealment of allocation of participants to treatment groups
was also assessed.22
Data relevant to manifestations of chronic insomnia were
analyzed qualitatively, while data relevant to management of
chronic insomnia were analyzed quantitatively.
Manifestations of Chronic Insomnia
For the questions on prevalence, natural history, incidence,
risk factors, and consequences of chronic insomnia, data
relevant to each variable were analyzed separately, except for
data relevant to potential risk factors and potential
consequences of chronic insomnia, which were analyzed
together as associated factors of chronic insomnia. The data
were synthesized to provide a description of the methods and
results of the studies relevant to a given variable.
Management of Chronic Insomnia
For continuous outcomes (e.g., sleep onset latency and sleep
efficiency), studies were combined using a mean difference
(MD), with the exception of sleep quality and quality of life,
where studies were combined using a standardized mean
difference (SMD). Dichotomous outcomes (i.e., safety
outcomes) were combined using a risk difference (RD). A number needed to harm (NNH) was also reported for any
safety outcomes that were found to be statistically significant.
The Inverse Variance Method23 was used to weight the studies.
An efficacy estimate, with corresponding 95% confidence
interval, was computed for each outcome. All meta-analyses
were performed using a Random Effects Model.24
For some outcomes (sleep onset latency and number of
adverse events), treatment categories were compared indirectly,
via their relationship to placebo. Differences of differences
with 95% confidence intervals (CI) were computed.
All estimates of efficacy were assessed for heterogeneity
using the I-squared statistic.25 For our primary outcome (sleep
onset latency), heterogeneity was explored in subgroup and
sensitivity analyses using a number of variables (treatment,
presence/absence of psychiatric illness, length of treatment,
age, gender and study quality). Deeks' chi-square statistic26
was used to test for significant heterogeneity reduction in
We tested for publication bias visually using the Funnel
Plot27 and quantitatively using the Rank Correlation Test,28 the
Graphical Test,29 and the Trim and Fill Method.30
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Prevalence of Chronic Insomnia
In general populations: Interquartile Range (IQR): 8.5-24.3 percent. There was evidence of an association between
female gender and chronic insomnia.
- In clinical populations: IQR: 27.8-43.0 percent.
- In outpatients of general practice: IQR: 19.8-53.7 percent.
- The majority of studies were either of moderate or high quality.
Natural History of Chronic Insomnia
- Only one study provided evidence on natural history of chronic insomnia: the remission rate was 13.1 percent after a 4-month followup period in a population suffering from insomnia for 1 month or more.
- The study was of moderate quality.
Incidence of Chronic Insomnia
- No studies were identified that provided evidence on incidence of chronic insomnia.
Factors Associated with Chronic
Potential Risk Factors
- Age. Eleven studies found evidence of an association
between age and chronic insomnia, whereas seven studies
found no evidence of an association between these
variables. Of the studies that found an association, all,
except one,31 found evidence that chronic insomnia is
associated with older age.
- Gender. Eleven studies found evidence of an association
between gender and chronic insomnia, while seven
studies found no evidence of an association between these
variables. All of the studies that found evidence of an
association between gender and chronic insomnia, found
evidence that chronic insomnia is associated with female
- Race/ethnicity. Two studies found evidence of an
association between ethnicity and chronic insomnia,32-33
while one study found no evidence of an association
between these variables.34 Bixler, et al. found evidence
that chronic insomnia is associated with being a non-Caucasian minority, and Riedel, et al. found evidence that
chronic insomnia is associated with being White.
- Psychiatric illness and psychological problems. Thirty-eight
studies found evidence of an association between
present or past psychiatric illness or psychological
problems and chronic insomnia. Seven studies did not
find evidence of an association between these variables.
- Medical conditions. Twelve studies found evidence of an
association between medical conditions or poor general
health and chronic insomnia, while one study35 did not
find evidence of an association between these variables.
- Socioeconomic status. Six studies found evidence of an
association between socioeconomic status and chronic
insomnia. Nine studies did not find evidence of an
association between these variables.
- Shift work. Only 2 studies provided evidence regarding
the relationship between shift-work and chronic
insomnia.31,36 The study by Kageyama, et al. provided
evidence that chronic insomnia is associated with three or
less night shifts per month within the preceding three
months in hospital nurses. The study by Martikainen et
al. found no evidence of an association between shift
work and chronic insomnia.
- Healthcare utilization. Five studies provided evidence of
an association between increased healthcare utilization
and chronic insomnia. One study did not find evidence
of an association between chronic insomnia and
undergoing medical treatment in hospital nurses.31
- Absenteeism and work performance. Only two studies
provided evidence regarding the relationship between
work performance or absenteeism and chronic
insomnia;37-38 both studies found evidence of an
association between chronic insomnia and absenteeism.
The study by Zammit, et al. also found evidence of an
association between chronic insomnia and impaired work
- Quality of life and quality of social relationships. Five
studies examined the relationship between either quality
of life (from a global perspective) or quality of social
relationships and chronic insomnia. All studies found
evidence of an association between chronic insomnia and
either lower quality of life or lower quality of social
relationships; one of these studies found evidence that
both quality of life and quality of social relationships are
impaired in chronic insomniacs.39
- Memory, cognitive function, and mood. Fifteen studies
found evidence of an association between decrements in
memory, mood or cognitive function and chronic
insomnia. One study40 found evidence of increased recall
of presentations made just before sleep onset in chronic
insomniacs. Eleven studies found no evidence of an
association between mood, memory, or cognitive function
and chronic insomnia.
We did not identify any studies that provided data relevant
to the relationship between accidents or falls in the elderly and
chronic insomnia or direct and indirect costs of the disorder.
The majority of studies were of either moderate or high
Efficacy and Safety of the Six Main
Categories of Interventions Identified in
The efficacy estimates are provided as mean differences
(MDs) in the effect of intervention and placebo on sleep onset
latency (SOL) or wakefulness after sleep onset (WASO). The
safety estimates are provided as risk differences (RDs) between
intervention and placebo.
- Benzodiazepines. MD (SOL): -16.5, 95% CI: (-20.5, -12.5); MD (WASO): -23.1, 95% CI: (-35.7, -10.5); RD:
0.15, 95% CI: (0.10, 0.20); number needed to harm was
- Non-benzodiazepines. MD (SOL): -18.1, 95% CI: (-22.5, -13.7); MD (WASO): -12.6, 95% CI: (-23.0, -2.3);
RD: 0.05, 95% CI: (0.01, 0.09); number needed to
harm was 20.
- Antidepressants. MD (SOL): -7.4, 95% CI (-10.5, -4.4);
MD (WASO): -11.4, 95% CI: (-16.2, -6.6); RD: 0.09,
95% CI (0.01, 0.18); number needed to harm was 12.
- L-Tryptophan. MD (SOL): -11.0, 95% CI: (-33.0,
- Melatonin. MD (SOL): -8.3, 95% CI: (-14.5, -2.0);
MD (WASO): -9.7, 95% CI: (-33.6, 14.3); RD: 0.09,
95% CI: (-0.11, 0.29).
- Valerian. MD (SOL): -1.3, 95% CI: (-21.4, 18.9); MD
(WASO): -8.4, 95% CI: (-15.9, -1.0); RD: -0.06, 95%
CI: (-0.48, 0.35).
- Relaxation therapy. MD (SOL): -14.6, 95% CI: (-29.3,
0.2); MD (WASO): -1.6, 95% CI: (-14.1, 10.8). No
adverse event data was provided.
- Cognitive/behavioral therapy. MD (SOL): -4.6, 95%
CI: (-9.8, 0.6); MD (WASO): -18.2, 95% CI: (-30.4, -6.0). No adverse event data was provided.
Most studies were of moderate or high quality.
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Prevalence, Natural History, Incidence, and
Factors Associated with Chronic Insomnia
The interquartile range of prevalence varied from 8.5-24.3
percent across high-quality studies of general populations, to
19.8-53.7 percent across moderate-quality studies of
outpatient populations, to 27.8-43.0 percent across moderate-quality
studies of clinical populations. Therefore, the
prevalence estimates for chronic insomnia in outpatient and
clinical populations appear to be significantly higher than
those for the general population, a finding that is consistent
with evidence of an association between chronic insomnia and medical conditions, poor general health, and increased
Only one study provided data on the natural history of
chronic insomnia; the remission rate was 13.1 percent after a
4-month followup. More research is necessary to determine
the course of chronic insomnia in various populations. We did
not identify any studies that provided evidence regarding the
incidence of chronic insomnia; more research is needed in this
area as well.
We found evidence to suggest that chronic insomnia is
associated with older age, female gender, present or past
psychiatric illness and psychological problems, medical
conditions and poor general health, increased healthcare
utilization, lower quality of life and social relationships,
socioeconomic status (marital separation, unemployment,
poorer working conditions, and lower social status), and
decrements in memory, mood, and cognitive function. Some
of the factors that are thought to contribute to insomnia in the
elderly include multiple medical problems, polypharmacy, and
environmental factors such as absence of zeitgebers
(time/schedule cues).11,41 Similarly, factors such as stress,
pregnancy, menopause, medical conditions, and complex
home life may explain the higher prevalence of insomnia in
Efficacy and Safety of Treatments for
The interventions for chronic insomnia that were
investigated in included studies may be categorized as either
benzodiazepines, non-benzodiazepines, antidepressants,
complementary and alternative care (L-tryptophan, melatonin
and valerian), relaxation therapy, cognitive/behavioral therapy,
barbiturates, hormone therapy, alcohol, low energy emission
therapy, and combination therapy. The majority of studies
were classified under the first six categories of the preceding
The review provides evidence that benzodiazepines and
non-benzodiazepines are effective treatments for chronic
insomnia. There is some evidence that antidepressants are
effective treatments for chronic insomnia, although more
research is required in this area. The review provides some
evidence that melatonin is effective in subsets of the chronic
insomnia population; however, more research is required in
this area. There is also evidence that relaxation therapy and
cognitive/behavioral therapy are effective treatments in subsets
of the chronic insomnia population.
There were too few
studies of L-tryptophan and valerian to draw conclusions
regarding the efficacy of these treatments in the management
of chronic insomnia: additional large-scale, randomized trials
are needed. Additional large-scale, randomized trials are also
needed in the area of relaxation therapy and cognitive/behavioral therapy in the management of chronic insomnia to
determine the efficacy of these interventions across subsets of
the chronic insomnia population.
The reduction in sleep
onset latency by benzodiazepines and non-benzodiazepines was
significantly greater than that for antidepressants and
melatonin, based on indirect comparisons. However, it should
be noted that there were significantly fewer studies of
antidepressants and melatonin compared to benzodiazepines
and non-benzodiazepines, and additional large-scale,
randomized trials of the former interventions are needed
before firm conclusions can be drawn regarding the relative
efficacy of these interventions.
The benzodiazepines, non-benzodiazepines, and
antidepressants had a significantly greater risk of harm than
placebo, while melatonin did not. There were too few studies
of L-tryptophan to draw conclusions regarding the safety of
this intervention. Although there was no evidence that
valerian poses a risk of harm, this result was based on only
three studies of relatively small sample size. Therefore, more
studies are needed before firm conclusions can be drawn
regarding the safety of valerian. The risk for benzodiazepines
was significantly greater than for non-benzodiazepines, based
on indirect comparisons. Indeed, benzodiazepine use has been
shown to increase the risk of injury in the elderly,42 and there is
pharmacologic evidence that the non-benzodiazepines have a
better side-effect profile than the benzodiazepines.43-44 Studies
of relaxation therapy and cognitive/behavioral therapy did not
provide adverse event data.
There was substantial heterogeneity in the pooled estimate
for SOL for benzodiazepines, non-benzodiazepines, L-tryptophan,
valerian, and relaxation therapy. Similarly, there
was substantial heterogeneity in the pooled estimate for
WASO for benzodiazepines, non-benzodiazepines, melatonin,
and cognitive/behavioral therapy. The heterogeneity was often
due to differences in the magnitude of the point estimate and
confidence interval across studies, rather than differences in the
directionality of the effect. The exceptions are for estimates of
the efficacy of relaxation therapy with respect to SOL and the
efficacy of melatonin with respect to WASO. The
heterogeneity in the pooled estimates for SOL was explored in sensitivity and sub-group analyses. The results indicate that
heterogeneity in the pooled estimate for SOL for relaxation
therapy is at least partially due to type of relaxation therapy,
length of treatment, age and gender distribution of the study
population, and study quality.
There was strong evidence of publication bias in the pooled
estimates for SOL for the benzodiazepine and nonbenzodiazepine
categories of intervention. This finding
suggests that the true estimate of efficacy is lower than the
estimate calculated in the current analysis.
We identified a small sample of studies examining the
efficacy of combination treatments in the management of
chronic insomnia; some of these studies compared a
combination of treatments with placebo, while others
compared them with single treatment. Many comparisons did
not have data for our primary outcome, sleep onset latency,
and the majority of results were non-significant. The latter
finding may reflect the low power of these analyses. None of
the studies provided data on adverse events. We identified
only one study that compared the efficacy of a combined
pharmacological and psychological treatment with these
treatments administered sequentially. The research agenda for
the management of chronic insomnia should include an
evaluation of the efficacy and safety of combination treatments
and sequential treatments.
Our results relating to relaxation therapy and
cognitive/behavioral therapy are somewhat at odds with three
meta-analyses reviewing the efficacy of psychological
treatments in the management of chronic insomnia.45-47 The
difference in the findings may relate to key differences in the
conduct of the reviews. First, we restricted our meta-analysis
to a review of placebo-controlled, randomized trials and
accounted for placebo effects in our estimations of efficacy. Other meta-analyses have included non-controlled studies, and
for these studies, have not accounted for placebo/control
effects in their estimation of efficacy. Second, we used clearly
defined criteria for chronic insomnia; however, for some
studies the criteria for insomnia was not clear. Third, we
separated predominantly cognitive/behavioral approaches from
predominantly relaxation approaches in management of
insomnia, resulting in distinct meta-analyses for each category
of intervention. These interventions have been grouped under
the broader heading of psychological/non-pharmacological
treatments in other reviews.
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- There is evidence that the prevalence of chronic insomnia
in outpatient and clinical populations is larger than in the
- There is evidence that chronic insomnia is associated with
older age, female gender, present or past psychiatric illness
and psychological problems, medical conditions and poor
general health, increased healthcare utilization, lower
quality of life and social relationships, socioeconomic
status (marital separation, unemployment, poorer
working conditions and lower social status), and
decrements in memory, mood, and cognitive function.
- Additional studies are needed to determine the incidence
and natural history of chronic insomnia in adults.
Similarly, additional studies are needed to explore the
relationship between chronic insomnia and race/ethnicity,
shift work, absenteeism, work performance, accidents,
falls in the elderly, and the direct and indirect costs of the
disorder. It is necessary that longitudinal studies be
undertaken to explore the risk factors and consequences
of chronic insomnia.
- There is evidence that benzodiazepines and non-benzodiazepines
are effective in the management of
chronic insomnia. There is some evidence that
antidepressants are effective in the management of
chronic insomnia: more research is required in this area.
There is evidence that benzodiazepines, non-benzodiazepines,
and antidepressants pose a risk of harm.
- There is some evidence that melatonin is effective in the
management of chronic insomnia in subsets of the
chronic insomnia population, and there is no evidence
that melatonin poses a risk of harm. However, more
research is required in this area given that the results are
based on a small number of studies. Similarly, additional
large-scale, randomized trials are needed to determine the
efficacy of melatonin across subsets of the chronic
insomnia population. There is insufficient evidence to
conclude on the efficacy and safety of L-tryptophan and
valerian in the management of chronic insomnia.
Additional large-scale, randomized trials are needed in
- There is evidence that relaxation therapy and
cognitive/behavioral therapy are effective in the
management of chronic insomnia in subsets of the
chronic insomnia population. Additional large-scale,
randomized trials are needed to determine their efficacy
across subsets of the chronic insomnia population.
There is evidence that benzodiazepines have a greater risk
of harm than non-benzodiazepines.
- There is insufficient evidence to conclude whether there
are differences between the short- and long-term efficacy
and safety of the various categories of interventions in the
management of chronic insomnia; additional long-term
studies are needed.
- There is insufficient evidence regarding the efficacy and
safety of combined treatments of pharmacological and
psychological interventions, and sequential treatments, in
the management of chronic insomnia; additional studies
are needed in these areas.
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Availability of Full Report
The full evidence report from which this summary was
taken was prepared for the Agency for Healthcare Research
and Quality (AHRQ) by the University of Alberta Evidence-based
Practice Center, under Contract No. C400000021. It is
expected to be available in June 2005. At that time, printed
copies may be obtained free of charge from the AHRQ
Publications Clearinghouse by calling 800-358-9295.
Requesters should ask for Evidence Report/Technology
Assessment No. 125, Manifestations and Management of
Chronic Insomnia in Adults.
The Evidence Report is also online on the National Library of Medicine Bookshelf, or can be downloaded as a PDF File (1.8 MB). Plugin Software Help.
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AHRQ Publication Number 05-E021-1
Current as of June 2005