insomnia

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Precipitating Factors ofInsomniaCelyne H. Bastien , Annie Vallieres & Charles M.MorinPublished online: 07 Jun 2010.

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Precipitating Factors of Insomnia

Célyne H. Bastien, Annie Vallières, and Charles M. MorinÉcole de psychologie and Centre d’étude des troubles du sommeil

Université LavalQuébec, Canada

Insomnia is a prevalent health complaint whose onset is precipitated by a variety offactors. There is an important need to identify and describe these factors to improveour understanding of risk factors and the natural history of insomnia. This article isaimed at identifying and describing the types of precipitating factors related to theonset of insomnia. A total of 345 patients evaluated for insomnia at a sleep-disordersclinic completed a sleep survey and underwent a semistructured clinical interview.As part of the evaluation, the specific precipitating events related to the onset of in-somnia were identified. Subsequently, these factors were categorized (work–school,family, physical or psychological health, or indeterminate), and their affective va-lence (negative, positive, or indeterminate) was coded. The most common precipitat-ing factors of insomnia were related to family, health, and work–school events.Sixty-five percent of precipitating events had a negative valence. These events dif-fered with the age of onset of insomnia but not with the gender of participants. Thesefindings are useful to identify potential risk factors for insomnia and improve our un-derstanding of the natural history of insomnia.

Epidemiological surveys estimate that 9% to 15% of adults complain of chronic in-somnia, whereas 27% complain of occasional insomnia (Ford & Kamerow, 1989;Gallup Organization, 1991; Mellinger, Balter, & Uhlenhuth, 1985). Prevalence es-timates are higher among women, older adults, and among patients with medicaland psychological disorders (Bixler, Kales, & Soldatos, 1979). Three types of con-tributing factors have been linked to insomnia: predisposing, precipitating, andperpetuating factors, each of them playing a different role at different points in thecourse of insomnia (Spielman & Glovinsky, 1991). For instance, several psycho-logical (Borkovec, 1982), physiological (Spielman & Glovinsky, 1991), and famil-

BEHAVIORAL SLEEP MEDICINE, 2(1), 50–62Copyright © 2004, Lawrence Erlbaum Associates, Inc.

Requests for reprints should be sent to Célyne H. Bastien, École de Psychologie, Université Laval,Ste-Foy, Québec, Canada G1K 7P4. E-mail: [email protected]

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ial or hereditary (Bastien & Morin, 2000; Hauri & Olmstead, 1980) factors havebeen hypothesized to predispose to insomnia. Other risk factors, categorized asprecipitating events, have been linked indirectly to the onset of insomnia(Borkovec, 1982; Chilcott & Shapiro, 1996; Kales & Vgontzas, 1992; Morin,1993). Those included psychological and physical dysfunctions, environmental,family, and work-related factors (Morin, 1993). Maladaptive sleep habits, poorsleep hygiene, and dysfunctional beliefs and attitudes about sleep have been asso-ciated with the perpetuation of insomnia (Morin, 1993).

Stress may be the most common precipitant of insomnia. In a retrospectivestudy, 74% of poor sleepers recalled specific stressful life experiences associatedwith the onset of their insomnia (Healy et al., 1981). These events were reportedmore frequently during the year the sleep problem began than in either the previousor subsequent years. The most common precipitants of insomnia were significantlosses through separation, divorce, or the death of a loved one. In another study(Vollrath, Wicki, & Angst, 1989) a greater frequency of negative life events(mostly related to interpersonal relationship), diminished coping skills, and lowerself-esteem were reported among individuals with insomnia compared to normalcontrols. However, when depression was partialled out, group differences were nolonger apparent. The rate of reported sleep disturbances among residents of Israelwas much higher during than before or after the Gulf War (Askenasy & Lewin,1996). Together, these findings suggest that the onset of sleep disturbances is oftenpreceded by negative or stressful life events.

Two longitudinal studies investigated the relations of age, gender, and health tothe onset of insomnia in a general adult population (Katz & McHorney, 1998;Klink, Quan, Kaltenborn, & Lebowitz, 1992). Depression, medical conditions in-terfering with sleep (e.g., cardiopulmonary, painful musculoskeletal, and prostatediseases), and lifestyle factors such as a high level of daytime activity were themost likely events associated with the onset of insomnia. Similar factors were alsoidentified as important precipitants of insomnia among older adults, even aftercontrolling for covariant predisposing factors such as age and gender (Morgan &Clarke, 1997; Roberts, Shena, & Kaplan, 1999). The study by Roberts et al. (1999)showed that women with mood disturbances and chronic health problems wereparticularly at greater risk for developing insomnia.

The impact of traffic road noise at night on the onset of insomnia was recentlyevaluated in a Japanese population (Kageyama et al., 1997). It was found that liv-ing near a road with a heavy volume of traffic represented a high risk factor to pre-cipitate insomnia. Living with a child 6 years or younger, undergoing medicaltreatment, and experiencing major life events were other potential precipitatingfactors reported in that same study.

In summary, several psychological, health, lifestyle, and environmental factorshave been linked indirectly to insomnia, and only one survey has examined the re-lation of stressful life events to the onset of insomnia. Additional research with

PRECIPITATING FACTORS OF INSOMNIA 51

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treatment-seeking individuals is needed to document more precisely the types ofevents that are temporally associated with the onset of insomnia. Such data wouldyield useful information about risk factors for insomnia. The aim of this study is toidentify the types of precipitating factors associated with the onset of insomnia andto determine if their nature varies according to age, gender, age of insomnia onset,subtypes and severity of insomnia. It is expected that more negative than positiveevents will be associated with the onset of insomnia. It is also expected that as peo-ple grow older, health factors will increasingly be reported as precipitating factorsof insomnia.

METHOD

Participants

The participants were 345 clinical patients presenting themselves to a sleep-disor-ders center. The participants were 192 women and 153 men with a mean age of42.1 years (SD = 14.5, range 17–82) and a mean education level of 14.5 years (SD= 3.2). They were community residents, predominantly married (49.6%), and wereemployed or at school (72.6%). Mean average insomnia duration was 10.1 years(SD = 11.5), with a mean age of insomnia onset of 32.0 years (SD = 16.5). Thetypes of insomnia complaints involved sleep onset (17.9%), sleep maintenance(18.2%), or mixed onset and maintenance difficulties (60.8%). The only criterionfor inclusion was that the primary complaint was insomnia. There were no exclu-sion criteria for this study.

Procedure

Data were compiled from a clinical interview obtained from participants pre-senting themselves at a sleep-disorders center with a chief complaint of insom-nia. All participants underwent a standard assessment protocol. First, a sleep sur-vey and the Insomnia Severity Index (ISI; Bastien, Vallières, & Morin, 2001;Morin, 1993) were completed. The ISI includes five questions about the partici-pants’ sleep difficulties estimated on Likert-type scales ranging from 0 (absent)to 4 (extremely severe) for a maximum score of 28 (0–7: no clinically significantinsomnia; 8–14: subthreshold insomnia; 15–21: clinical insomnia –moderate se-verity; 22–28: clinical insomnia–severe). The items evaluate the severity of sleeponset, sleep maintenance, early morning awakening problems, satisfaction withcurrent sleep pattern, interference with daily functioning, noticeable impairmentattributed to the sleep problem, and level of distress caused by the sleep prob-lem. The ISI (Bastien et al., 2001) has adequate psychometric properties (inter-nal consistency of .74) and has been shown to be sensitive to changes in clinical

52 BASTIEN, VALLIÈRES, MORIN

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trials of insomnia. The assessment protocol also included psychometric ques-tionnaires (e.g., Beck Depression Inventory [BDI] and State–Trait Anxiety In-ventory [STAI]), a medical history, and completion of a clinical evaluation (in-vestigating any psychopathology or mental disorders according to Diagnosticand Statistical Manual of Mental Disorders–Fourth Edition [DSM–IV] criteria).About half of the participants completed at least 1 week of sleep diary. The sur-vey, questionnaires, and diaries were self-administered.

The clinical evaluation was conducted by a board-certified sleep specialist(CM; 85% of patients) or a postdoctoral fellow in clinical psychology (15% of pa-tients). All information pertaining to the nature, severity, onset, course, and precip-itating circumstances of insomnia was obtained with a semistructured clinical in-terview (Morin, 1993) aimed at circumscribing the sleep difficulties (onset, type,development, and sleep hygiene) and based on DSM–IV criteria for insomnia. Aspart of this evaluation, the clinician investigated any factor or life event that pre-ceded or was associated temporally with the onset of insomnia. The followingquestion was asked of the participant: “To your recollection, are there any lifeevents that may be linked to the onset of your sleep difficulties?” When there wasmore than one precipitating factor associated with the onset of insomnia, the clini-cian made a determination, after thorough consideration of the full evaluation, ofwhich was the most important by asking “Which one of these events would you sayhad more impact on your sleep?” The precipitating factor was subsequently codedby the clinician into either one of six categories: work–school, family, health,psychopathology, other, and indeterminate. Indeterminate was coded when neitherthe patient nor the clinician could identify a precipitating factor. Within each cate-gory, specific subtypes of events were identified. For example, the health categoryincluded events such as a medical illness, a hospitalization, pain, and menopause.The events were subsequently coded according to their affective valence (negativeimpact on life in general—perceived as a negative event by the participant; positiveimpact on life in general—perceived as a positive event by the participant; or neu-tral impact).

Statistical Analysis

First, descriptive analyses were computed for the total sample (demographic data),as a function of the different category of precipitating events, as well as for theirsubtypes and affective valence. Second, chi-square analyses were performed forthe category as a function of gender and the median age of onset of insomnia.Finally, one-way analyses of variance (ANOVAs) were computed to evaluatewhether categories and subtypes of precipitating factors varied according to thenature, severity, and course of insomnia. An alpha level of .05 was used to assesssignificant differences.


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RESULTS

Data on precipitating factors were available for 327 participants. Eighteen participantswere excluded from the initial sample because of missing or ambiguous data aboutprecipitating factors. Of the 327 participants, 39.2% reported that the development oftheir insomnia was gradual, 37.5% reported a sudden onset, and 24.3% could not de-termine the nature of their insomnia onset. The large majority of the sample reportedthat their insomnia was chronic, whereas 23.3% reported an episodic course. Mean se-verity of sleep difficulties from the ISI was 21.7 (SD = 4.4; maximum score for thescale being 28). The average sleep efficiency computed from the baseline diary datawas 67.7% (SD = 17.8). Mean scores on the BDI and on the STAI trait and state scaleswere 14.1 (SD = 8.3), 46.0 (SD = 10.6), and 45.8 (SD = 11.7), respectively.

The frequencies and percentages for each category and subtype of precipitatingfactorsarepresented inTable1.Aspecificprecipitatingevent,or combinationofcir-cumstances, could be identified in 78.3% of the sample. No precipitant could beidentified in 21.7% of the patients. As only 34 participants reported more than oneprecipitating factor, only the primaryprecipitating event, as determined by the clini-cian, was retained for further analyses. Among the six categories of major


TABLE 1Categories and Subtypes of Precipitating Factors

Categories n % Subtypes % Within Category Total %

Health 75 22.9a Pain 38.7a 11.1Medical illness 37.3a 10.7Hospitalization 18.7b 5.4

Menopause 5.3b 1.5Family 78 23.9a Separation 21.5 6.5

Marital problem 17.7 5.4Family member illness 11.4 4.6

Death of a significant person 15.2 4.2Sexual or physical abuse 13.9 3.4

Birth of child 11.4 3.4Caregiving 7.6 2.3

Other 1.3 0.4Work–school 56 17.1a Stress at work–school 61.8a 13.4

Rotating shift 23.6a 5.0Employment change 12.7b 2.7

Retirement 1.8b 0.4Psychopathology 38 11.6b Major affective disorder 80.5a 12.6

Substance abuse 19.5b 3.1Other 13 2.8b — — 3.9Indeterminate 71 21.7a — — —

Note. Significant differences between subgroups in the same category are represented by differ-ent letters superscripts.

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precipitants, factors related to health, family, and work–school stress were the mostfrequently reported, χ2(5, N = 327) = 67.0, p < .0001. Of all health-related precipitat-ing factors, the most frequently identified subtypes were pain and medical illness,χ2(3, N = 75) = 23.0, p < .0001, whereas hospitalization and menopause were muchless frequently reported. For those who reported family-related precipitating fac-tors, all subtypes were equally reported, χ2(6, N = 78) = 7.1, ns. Stress in the work-place or at school and rotating shift were the most common subtypes in the work andschool category, followed by change of employment and retirement, χ2(4, N = 55) =17.5, p < .002. Finally, even if psychopathologywas not reported as frequentlyas theprevious three categories, the incidence of major affective disorder was more fre-quent than substance or alcohol abuse, χ2(1, N = 41) = 15.2, p < .0001.

The large majority of precipitating factors was judged to have a negative va-lence (65%), whereas only 4.6% had a positive valence. Birth of a child and changeof employment were the precipitating factors most frequently identified as havinga positive valence. For 31%, it could not be determined whether the precipitatingevent had a positive or negative valence.

Age of Onset of Insomnia and Gender

Table 2 presents the frequency of different precipitating factors according to age ofonset of insomnia and gender. The median age of onset of insomnia was used toform 2 groups: onset ≤ 30 (n = 167; 78 men, 89 women) and onset > 30 (n = 169;73 men, 96 women). There were significant differences in frequency of precipitat-ing factors according to age of onset, χ2(5, N = 323) = 40.1, p < .0001, but not ac-cording to gender, χ2(5, N = 327) = 8.0, ns. Health problems were more often re-ported as a precipitating factor when the onset of insomnia was after age 30. Whenthe onset of insomnia was before age 30, the most frequent precipitating factorswere occupational or school-related stress. Family factors were reported equallyfrequently as a precipitating event of sleep difficulties in both groups. Collectively


TABLE 2Type of Precipitating Factors According to Age of Onset of Insomnia and

Gender

Onset 30 Onset > 30 Women Men

Type of Factors n % n % n % n %

Health 17 10.6b,c 60 36.8a,d 50 24.1 26 18.6Family 41 24.8a 43 26.4a 50 27.5 35 24.1Psychopathology 20 12.5b 21 12.9b 24 13.2 18 12.4Work–school 41 25.6a,d 23 14.1b,d 30 16.5 35 24.1Other 8 5.0b 3 1.8b 7 3.8 4 2.8Indeterminate 33 20.6a,d 13 8.0b,d 21 11.5 26 17.9

a,bSignificant differences within onset of insomnia groups, p < .0001. c,dSignificant differences be-tween onset of insomnia groups for the same type of factor, p < .001.

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and independently of age of onset and gender, psychopathology was less fre-quently reported as a precipitating factor of insomnia.

Diagnosis of Insomnia

Psychophysiological insomnia (n = 98; 31%) and insomnia secondary to a psychi-atric disorder (n = 77; 24%) were the two most frequent insomnia diagnoses, fol-lowed by insomnia associated with substance abuse (n = 36; 11%); the remainingparticipants (n = 107; 34%) had other insomnia diagnoses (e.g., associated withmedical conditions, other sleep disorders).

The types of precipitating events associated with the most common insomniadiagnoses are presented in Table 3. A family-related circumstance was more oftenreported as a precipitating event when the diagnosis was psychophysiological in-somnia. Not surprisingly, other than family, psychopathology (e.g., depression,anxiety) was the most frequently identified precipitating factor when the diagnosiswas insomnia secondary to psychopathology. Finally, work or school-relatedstress was reported as precipitating factors more often when the primary diagnosiswas insomnia associated with substance abuse.

Course and Nature of Insomnia

One-way ANOVAs were computed to evaluate whether categories and subtypes ofprecipitating factors varied according to the nature, severity, and course of insom-nia. The analyses revealed that neither categories nor subtypes of precipitating fac-tors varied as a function of these clinical parameters (nature: p = .585; severity: p =.516; course: p = .603). A one-way ANOVA also revealed that categories and sub-types of precipitants did not vary as a function of sleep efficiency computed from


TABLE 3Types of Precipitating Factors According to Diagnosis of Insomnia

Diagnosis

Psychophysiological Psychiatric Substance Abuse

Types of Factors n % n % n %

Health 19 19.4b 7 9.1b 6 16.7b

Family 31 31.6a 23 29.9a 7 19.4b

Work–school 24 24.5b 16 20.8b 10 27.8a

Psychopathology 11 11.2b 22 28.6a 4 11.1b

Other 3 3.1b 4 5.2b 2 5.6b

Indeterminate 10 10.2b 5 6.5b 7 19.4b

Note. Significant differences in the same category are represented by different superscripts.

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the sleep diary. However, a one-way ANOVA yielded a significant effect for cate-gory as a function of the frequency of use of sleep medications, F(5, 261) = 2.93, p= .014. Post hoc comparisons, using the Tukey honestly significant difference test,revealed that participants reporting a health-related precipitating factor were tak-ing medications more frequently (M = 1.49, SD = 1.54) than participants identify-ing a work–school-related precipitant (M = .69, SD = 1.16; p = .025). Frequency ofmedication intake for sleep difficulties was similar in the other four categories ofprecipitating factors.

DISCUSSION

This study shows that problems related to health, family relationships, and work orschool are the most common precipitating factors associated with the onset of in-somnia. The nature of these events vary with the age of onset and specific insomniadiagnosis, but not with the gender of the participant or with the nature, course, orseverity of the sleep difficulties. When a precipitating factor is identified, it is gen-erally perceived as a negative event.

Pain and general medical illness accounted for 22% of all health-related fac-tors associated with the onset of insomnia. These results are consistent with pre-vious findings reporting health as an important precipitating factor of insomnia(Katz & McHorney, 1998; Klink et al., 1992; Morgan & Clarke, 1997; Robertset al., 1999). Although it is unclear whether health problems per se or worriesabout health trigger insomnia, individuals with health problems are likely to beat greater risk for chronic insomnia. Menopause and hospitalization were notidentified as precipitating factors of insomnia as often as one might have pre-dicted. Only four of the 96 women older than 50 years reported menopause asthe major precipitating factor of their sleep difficulties. However, it is also plau-sible that postmenopausal women who attribute their sleep difficulties to hor-monal factors consult their primary care physicians for hormonal therapy ratherthan a sleep clinic. Given the relatively infrequent occurrence of hospitalization,although remaining stressful, its impact on the onset of insomnia remains un-clear, at least in terms of its affect on sleep quality. Nonetheless, it is possiblethat the chance of developing persistent insomnia increases with the time spentin the hospital or with certain consequences associated with hospital stay orother medication intake (i.e., recovering from surgery, prescribed medication forhealth problems).

Every subtype of factors in the family category was equally linked to the onsetof insomnia. Our results corroborate only partially previous data suggesting thatmarital difficulties, divorce, or separation were among the most common factorsassociated with the onset of insomnia (Morin, 1993). Furthermore, dysfunctional


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relationships within the family seem to be a common precipitating factor across allinsomnia diagnoses.

In the work–school category, several sources of stress were identified as precip-itating insomnia. Those included conflicts with a supervisor, interpersonal rela-tionship difficulties, workload, and financial strain. These results concur with ear-lier findings (Ribet & Derriennic, 1999) that occupational stress is frequentlyassociated with sleep disturbances. On the other hand, other infrequent life eventssuch as change of employment or retirement were the least frequent precipitatorsof insomnia. This is not surprising given that 63% of our participants were workingor studying, and only 1.5% were retired; furthermore, the mean age of our samplewas 42 years. It is likely that retirement might have been associated more fre-quently with the onset of sleep disturbances in a sample of older adults.

Psychopathology accounted for only 12% of all reported precipitating factorsof insomnia. This finding is surprising because more than one third of our samplereceived a primary diagnosis of insomnia associated with psychopathology or sub-stance abuse. Although it is well recognized that psychopathology is an importantrisk factor for insomnia, recent evidence also suggests that chronic and untreatedsleep disturbances may be a risk factor for psychopathology (major depression,anxiety; Breslau, Roth, Rosenthal, & Andreski, 1996; Foley, Monjan, Izmirlian,Hays, & Blazer, 1999; Ford & Kamerow, 1989; Morin, Stone, McDonald, & Jones,1994). Our results preclude this distinction and simply reflect the clinicians’ andpatients’perception of the most important factor precipitating insomnia. It remainsunclear whether these results reflect an underestimation of the influence of psy-chological dysfunctions on insomnia or that psychopathology developed as aby-product of another stressful life event (e.g., occupational or family stress) andwas not directly associated with the onset of insomnia.

Consistent with previous findings (Morgan & Clarke, 1997; Roberts et al.,1999), age of onset of insomnia was related to the subtypes of precipitating factors.For example, precipitants related to work or school were more common when theonset of insomnia was earlier in life, whereas health factors were more often asso-ciated with an insomnia onset later in life. The proportion of participants whocould not identify a precipitating factor was relatively high. The earlier the insom-nia onset, the more difficult it was to identify a precipitating factor. In that regard,two explanations might be offered. First, insomnia was reported to have developedgradually for a large subset of the sample (n = 115; 39.2%), making it more diffi-cult to associate its onset with a specific precipitating event. Second, it is possiblethat as the interval of time between the onset of insomnia and the clinical interviewlengthens, the more likely participants were to have recall problems or some mem-ory bias surrounding the event that precipitated their sleep difficulties.

The interpretation of these findings is, however, tinted by some limitations.First, there were no interrater reliability checks of the affective valence, thesubtyping of insomnia and psychopathology diagnosis between clinicians. Al-


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though clinicians were experienced and followed good clinical guidelines for diag-nosis, it is possible that diagnosis differed from one clinician to the other. Second,it is possible that some memory biases from clients were present. Those who reporta long duration of insomnia might be more prone to have such bias than thosewhose insomnia was more recent. Furthermore, when many factors are reported tohave contributed concurrently to the onset of insomnia, the imperativeness of hav-ing to choose the most influential factor might make participants uncomfortable,and results might be blurred by such bias. However, this again might also be a truereflection of insomnia. Although one major factor may be identified as related toits onset, insomnia is multidimensional in nature. More than one factor can oftencontribute to the onset, development, and maintenance of persistent insomnia, andthose factors might not be easily dissociated at times.

These findings still generate very informative results regarding potential riskfactors associated with primary and secondary diagnoses of insomnia, the identifi-cation of which is certainly a valuable step in treatment outcome, especially forplanning and preventing relapses. Possible links observed between precipitatingand perpetuating factors concur with etiological models of insomnia (Morin, 1993;Spielman, 1986) and have an impact on the elements chosen for the prevention andtreatment of insomnia. If one knows what has triggered insomnia the first time, onemight be able to prevent relapse afterward by working on those precipitating fac-tors and related events.

According to Spielman (1986), if some factors are also linked to the mainte-nance of insomnia (e.g., cognitive arousal, worry), the same factors might also pre-cipitate it. As such, Waters, Adams, Binks, & Varnado (1993), reported that nega-tive emotions, attention factors, and stress responsiveness are predictors ofincreases in sleep onset and maintenance difficulties. On the other hand, Watts,Coyle, & East (1994) also showed that worrying does interact with sleep. More re-cently, Hall, Buysse, Reynolds, Kupfer, & Baum (1996) reported that insomniacan be “precipitated” by stress-related intrusive thoughts. These data thus suggestthat worrying over different life events might be a precipitant of insomnia. Ourdata appear to support these observations. Most identified contextual and temporalfactors appear to be stress factors that can potentially generate worry. For example,health is a general worry as one grows older. If you are anxious by nature, predis-posed to worrying (and thus predisposed to develop insomnia), a health problemcan lead to substantial worry that will, in turn, translate into insomnia.

Recently, Espie (2002) proposed an integrated model of insomnia mainly sug-gesting a bidirectionality between sleep protectors, which have a defensive func-tion against external and internal stimuli able to disrupt or disturb sleep, and sleepitself. The protectors are reinforcing sleep and vice versa. Insomnia would result inan inhibition problem in at least one protector. If one protector is deficient, thensleep becomes deficient, and this might lead to insomnia. The precipitating factors,such as health, family, and work–school categories might lead to the first inhibition


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deficiency of a protector, creating the first night of insomnia. The inability of otherprotectors to compensate for the deficiency create a loss of sleep automaticity and,consequently, persistent insomnia. The identified factors in this study might alsotrigger an inhibition deficiency in more than one sleep protector, thus increasingfurthermore the risk of developing persistent insomnia.

Hyperarousal, which has been suggested as a predisposing factor of insomnia,is also a central constituent in Perlis, Giles, Mendelson, Bootzin, & Wyatt’s (1997)neurocognitive model of insomnia. Hyperarousal, defined as high cortical activity,becomes increasingly associated with stimuli usually associated with sleep (e.g.,going to bed). Hyperarousal is the inability to inhibit intrusive stimuli, both inter-nal (cognitive, physical) and external (environmental). By integrating both models(Espie, 2002; Perlis et al., 1997), hyperarousal (as defined by Perlis et al., 1997)would be the result of a deficiency in the de-arousal sleep protector (as defined byEspie, 2002). A deficient ability in the inhibition system may be present before theonset of insomnia but remain sufficiently active to maintain “good” sleep until af-ter being fully triggered by one or more stressors, or precipitating factors. The pre-cipitating factors identified in this study had a certain impact on sleep probably viathe cognitive and physiological arousal they produced while being interpreted asstressors to the individual. Although individuals who participated in this studywere not overly anxious (STAI mean scores), they still showed a reasonable anxi-ety base. A longitudinal protocol studying the “preinsomnia” moment, with goodsleepers and other individuals followed on a number of years, might be able to tar-get those individuals more at risk to develop later chronic insomnia.

In summary, these findings suggest that several types of factors contribute to theonset of insomnia and that the nature of those precipitating events may vary withthe age of onset. Each identified category may be integrated to the conceptualiza-tion models of insomnia as precipitating factors. It is possible that someprecipitants are chronic in nature and come to play a role in perpetuating sleep dif-ficulties over time. These maintaining factors could lead to inadequate stress-cop-ing strategies, maladaptive sleep habits, and dysfunctional beliefs and attitudesabout sleep (Foley et al., 1999; Healy et al., 1981; Morin et al., 1994; Ribet &Derriennic, 1999). Although these data do not inform us about the process under-lying a negative event associated with the development of chronic insomnia, theyare useful to identify potential risk factors for insomnia. Because retrospective dataare always subject to bias, it will be important in future research to conduct pro-spective and longitudinal analyses of risk factors for insomnia. Furthermore, thesedata were obtained in a clinical sample of participants seeking help for their sleepdifficulties, and no comparison group is available. Considering that the incidenceof insomnia is about 3.5% in young adults (Spielman, 1986) and 5% in older peo-ple (Waters et al., 1993), it would be interesting to conduct a longitudinal studyaimed at evaluating the premorbid factors associated with the development ofchronic insomnia.


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ACKNOWLEDGMENT

Preparation of this article was supported in part by the National Institute of MentalHealth Grant #MH55469 and the Fonds de la Recherche en Santé du Québec.

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