Schizophrenia Research 108 (2009) 280–284

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Insomnia and paranoia

Daniel Freeman⁎, Katherine Pugh, Natasha Vorontsova, Laura SouthgateDepartment of Psychology, Institute of Psychiatry, King's College London, United Kingdom

a r t i c l e i n f o

⁎ Corresponding author. Psychology Department, PPsychiatry, King's College London, Denmark Hill, LonKingdom.

E-mail address: D.Freeman@iop.kcl.ac.uk (D. Freem

0920-9964/$ – see front matter © 2008 Elsevier B.V.doi:10.1016/j.schres.2008.12.001

a b s t r a c t

Article history:Received 22 September 2008Received in revised form 20 November 2008Accepted 1 December 2008Available online 20 December 2008

Insomnia is a potential cause of anxiety, depression, and anomalies of experience; separateresearch has shown that anxiety, depression and anomalies of experience are predictors ofparanoia. Thus insomnia may contribute to the formation and maintenance of persecutoryideation. The aim was to examine for the first time the association of insomnia symptoms andparanoia in the general population and the extent of insomnia in individuals with persecutorydelusions attending psychiatric services. Assessments of insomnia, persecutory ideation,anxiety, and depressionwere completed by 300 individuals from the general population and 30individuals with persecutory delusions and a diagnosis of non-affective psychosis. Insomniasymptoms were clearly associated with higher levels of persecutory ideation. Consistent withthe theoretical understanding of paranoia, the associationwas partly explained by the presenceof anxiety and depression. Moderate or severe insomnia was present in more than 50% of thedelusions group. The study provides the first direct evidence that insomnia is common inindividuals with high levels of paranoia. It is plausible that sleep difficulties contribute to thedevelopment of persecutory ideation. The intriguing implication is that insomnia interventionsfor this group could have the added benefit of lessening paranoia.

© 2008 Elsevier B.V. All rights reserved.

Keywords:DelusionsPersecutoryParanoiaInsomniaPsychosis

1. Introduction

Clinical experience indicates that many individuals withpersecutory delusions have difficulties initiating and main-taining sleep. The extent of the problem has never beenreported. Often the insomnia is simply a result of insufficientactivity during the day and early retirement to bed. Howeverthe relationship between insomnia and paranoia may holdgreater clinical and theoretical interest. The stressful experi-ence of insomnia may lead to the lowering of mood andanomalies of experience that drive persecutory ideation. Theintriguing clinical implication is that simple well-establishedinterventions for sleep difficulties could lessen paranoidexperience.

There is evidence consistent with the idea that sleepdisturbance has a role in the development of paranoia.Insomnia is a risk factor for the development of emotional

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disorder (Ford and Kamerow,1989; Breslau et al.,1996;Morphyet al., 2007) and an associationwith daytimemood disturbancehas been repeatedly demonstrated (Riedel and Lichstein, 2000;Buysse et al., 2007). In separate research, paranoia has beenstrongly linked with negative affect (Freeman et al., 2008b;Bentall et al., in press), even being considered a type of anxiousfear (Freeman and Freeman, 2008). Therefore insomniamay beone cause of the negative mood that leads to paranoia.Anomalies of experience such as perceptual distortions andhallucinations are also considered a key cause of paranoia(Maher, 1988; Freeman et al., 2008a); therefore it is germanethat sleep deprivation has long been noted to producetemporary psychotic-like experiences (Luby et al., 1960; Westet al., 1962). Sleep difficulties are a common prodromal featureof schizophrenia (Birchwood et al., 1989; Yung and McGorry,1996) and even in unmedicated patients with schizophreniathere is evidence of increased sleep latency and decreased totalsleep time (Chouinard et al., 2004). At a neurobiological level ithas been suggested that the overactivity of dopamine D2receptors in the striatum thought to underlie the positivesymptoms of schizophrenia also enhances wakefulness (Montiand Monti, 2005).

281D. Freeman et al. / Schizophrenia Research 108 (2009) 280–284

Recent research demonstrates that paranoid thinking ismuch more common in the general population than pre-viously thought (Freeman et al., 2008b). A high prevalence ofinsomnia has been recognised for longer. Approximately 30%of the general population experience symptoms of insomnia,with a third of this group having chronic insomnia (Ohayon,2002;Walsh, 2004; Morin et al., 2006). This sleep disturbanceis associated with anxiety and depression (Taylor et al., 2005;Breslau et al., 1996; Buckner et al., 2008); indeed, difficultiesfalling or staying asleep are a symptom of the diagnoses ofdepression, generalised anxiety disorder, and post-traumaticstress disorder (APA, 2000). In the current study the aim wasto determine whether persecutory ideation and insomnia areassociated. A community samplewas used to obtain a range inparanoia severity and avoid the complicating issues ofneuroleptic medication and high levels of inactivity. At thesame time the occurrence of insomnia in a group of patientswith persecutory delusions attending psychiatric services forpsychosis was also examined.

2. Method

2.1. Participants

The community sample comprised 300 individuals. Therewere three entry criteria: aged 18 or above; able to read andwrite in English; and no history of treatment for severe mentalillness (e.g. schizophrenia, bipolar disorder). The sample wasrecruited via the distribution to local postcodes of leafletsadvertising research studies at King's College London. Thosewho responded to the leaflet were screened for the entrycriteria over the telephone. Questionnaires were then com-pleted at King's College London, by postal return or an Internetwebsite (only available to screened individuals). The clinicalgroup was recruited from adult services in the South Londonand Maudsley NHS Foundation Trust. The entry criteria werethe presence of a current persecutory delusion, which met thecriteria of Freeman and Garety (2000), and a clinical diagnosis ofschizophrenia, schizo-affective disorder, or delusional disorder(i.e. nonaffective psychosis).

2.2. Measures

2.2.1. Insomnia Severity Index (ISI) (Bastien et al., 2001)The ISI is a seven-item self-report questionnaire based upon

the insomnia criteria of the Diagnostic and Statistical Manual ofMentalDisorders (APA,1994). The scale assesses sleep-onset andsleep maintenance difficulties, associated distress, and inter-ferencewith daily functioning. Each item is rated on a 0–4 scale.The time period is the past fortnight. Higher scores indicate thepresence of symptoms of insomnia. The scalewas evaluated in asample of over two hundred individuals attending a sleepdisorders clinic, and has been repeatedly used in insomniastudies (Buckner et al., 2008; Savard et al., 2005; Bernert et al.,2007). The questionnaire shows convergent validity with dailysleep diaries, significant other reports and clinician ratings. Inthe current study the scale showed high internal reliability(Cronbach's Alpha=.89). The guidelines for the interpretation ofscores are: no clinically significant insomnia (0–7), subthresholdinsomnia (8–14), clinical insomnia of moderate severity (15–21)and severe clinical insomnia (22–28).

2.2.2. Sleep-50 Questionnaire (Spoormaker et al., 2005)The nine-item insomnia subscale of the Sleep-50 Ques-

tionnaire assesses difficulties falling and staying asleep over thepast month, but not interference with daily functioning. Eachitem is rated on a scale of 1 to 4. Higher scores indicate thepresence of symptoms of insomnia. The scale was psychome-trically evaluated in a sample of 400 students and 250 sleepclinic patients. In the current study the internal reliability of thescale was high (Cronbach's Alpha=.88). Clinical insomnia isindicated by a score of 19 or above.

2.2.3. Green et al. Paranoid Thoughts Scale— Part B (Green et al.,2008)

The G-PTS Part B is a self-report measure of the occurrenceof persecutory ideation in the past month. Each of the sixteenitems (e.g. ‘I was convinced there was a conspiracy against me’,‘Certain individuals have had it in forme’, ‘I have definitely beenpersecuted’) is rated on a scale from 1 to 5, and conforms to aclear definition of persecutory ideation (Freeman and Garety,2000). The total score can range from 16 to 80. Higher scoresindicate greater levels of persecutory thinking. The question-naire has been psychometrically evaluated for use in bothclinical and non-clinical populations. The internal consistencyof the scale and test–retest reliability are good. Convergentvalidity with the Paranoia Scale (Fenigstein and Vanable, 1992)has been shown. In the current study the scale had very highinternal reliability (Cronbach's Alpha=.94).

2.2.4. Depression Anxiety Stress Scales (Lovibond and Lovibond,1995)

The DASS is a 42-item instrument with three subscalesmeasuring symptomsofdepression, anxiety, and stressover thepast week. Each of the subscales consists of 14 itemswith a 0–3scale (0=did not apply tomeat all, 3=applied tomeverymuch).Higher scores indicate higher levels of emotional distress. Thescale has been shown to be reliable and valid in large clinicaland non-clinical populations (Brown et al., 1997; Crawford andHenry, 2003; Page et al., 2007). The anxietyanddepression sub-scales were used; each showed very high internal reliability inthe current study (Anxiety Cronbach's Alpha=.91, DepressionCronbach's Alpha=.96). There are no items on the scales thatassess sleep difficulties.

2.3. Analysis

Analyseswere carried out using Stata Version 10.0 (StataCorp,2008). Visual inspection showed that the measures of persecu-tory ideation, anxiety and depression in the community sampleall showed considerable positive skew; 46.7%, 34.3% and 31.0%had the minimum scores on the measures of paranoia, depres-sion and anxiety respectively. These variables were thereforerecoded into ordinal categories: Paranoia (16, 17–20, 21–24, 25–28, 29+), Depression (0,1–3, 4–6, 7–9,10–12,13+), Anxiety (0,1–3,4–6, 7–9, 10+). The main analyses were ordinal logistic regres-sions (using the Stata ologit command) with paranoia as thedependent variable. In the first stage insomnia was theindependent variable (controlling for age, sex, and workingstatus). In thesecondstagedepressionwasaddedasanadditionalindependent variable. In the final stage anxietywas added to themodel. This procedure was carried out separately for each of theinsomnia scales. There were no missing data. The models were

Table 2Ordinal logistic regressions for the community sample (N=300) with paranoiaas the dependent variable and controlling for age, sex and work status

Odds ratio p-value 95% CI

1. Insomnia Severity Index 1.16 b .001 1.11, 1.222. Insomnia Severity Index 1.09 b .001 1.04, 1.15

Depression 1.73 b .001 1.46, 2.033. Insomnia Severity Index 1.04 .180 .98, 1.09

Depression 1.33 .002 1.11, 1.60Anxiety 2.22 b .001 1.67, 2.96

1. Sleep-50 Insomnia 1.20 b .001 1.14, 1.262. Sleep-50 Insomnia 1.13 b .001 1.07, 1.19

Depression 1.67 b .001 1.41, 1.973. Sleep-50 Insomnia 1.07 .024 1.01, 1.13

Depression 1.31 .004 1.09, 1.58Anxiety 2.12 b .001 1.59, 2.82

282 D. Freeman et al. / Schizophrenia Research 108 (2009) 280–284

repeated adding the data for ethnicity and education level, whichhad missing data for three cases, but the results were unaltered.95% Confidence Intervals (CI) are reported.

3. Results

3.1. Community group

The community group comprised 140men and 160women.The mean age was 37.7 (SD=12.5). The reported ethnicitieswere: White (n=216), Black-Caribbean (n=16), Black African(n=18), Black-Other (n=6), Indian (n=6), Pakistani (n=1), andother (n=35). One hundred and six participants were workingfull-time, seventy were working part-time, thirteen wereretired, sixty-four were unemployed and forty-seven werestudents. The educational qualifications were: none (n=19),GCSE (n=57), AS/A-level (n=41), diploma (n=32), degree(n=97), postgraduate degree (n=53).

Scores on the measures are shown in Table 1. Based on theInsomnia Severity Index, 216 (72%) participants had noclinically significant insomnia, 62 (20.7%) participants hadsub-threshold insomnia, 17 (5.7%) participants had clinicalinsomnia of moderate severity and 5 (1.7%) participants hadsevere clinical insomnia. Therefore 28% of the communitysample had some degree of sleep difficulty. There was a highcorrelation between ISI and Sleep-50 Insomnia scores, r= .83,pb .001. Forty-six individuals (15.3%) scored above the cut-offon the Sleep-50, indicating potential clinical insomnia.

Ordinal logistic regressions examining the association ofparanoia and insomnia are reported in Table 2. There is astrong association of the insomnia scales with paranoia. Forthe interpretation of the results it should be remembered thatthe odds ratios for the insomnia scales refer to one-pointchanges. A ten-point increase in the Insomnia Severity Indexis associated with an odds ratio of 4.4 for an increase inparanoia category (1.16 raised to the power of 10). A ten-pointincrease on the Sleep-50 scale is associated with an odds ratioof 6.2 for an increase along the paranoia ordinal scale. 70% ofthose in the highest category of paranoia scores had at leastsub-threshold insomnia difficulties as assessed by the ISI,whereas this was the case for only 17% of the participantswithout any paranoid ideation. On the Sleep-50 question-naire, 59% in the highest paranoia category scored above thecut-off for insomnia, whereas only 8% in the lowest paranoiacategory scored similarly. It can be seen that when depressionis added to the regression models that the relationship ofinsomnia to paranoia is lessened but that there is a unique

Table 1Questionnaire scores

Community group(N=300)

Persecutory delusionsgroup (N=30)

Mean SD Min.–Max.

Mean SD Min.–Max.

Insomnia Severity Index 5.90 5.17 0–28 15.07 7.34 0–27Sleep-50 Insomnia 13.89 4.95 9–35 23.07 8.44 11–36GPTS-Part B

(persecutory ideation)19.94 7.85 16–73 65.27 13.49 39–80

DASS — Depression 4.42 6.99 0–42 26.63 11.17 2–41DASS — Anxiety 3.32 5.56 0–38 21.93 10.90 4–41

contribution of each variable to predicting paranoia scores.When anxiety is added then the relationship of insomnia toparanoia is lessened substantially further, becoming statisti-cally non-significant for the ISI.

3.2. Clinical group

The persecutory delusions group comprised 18 men and 12women. The mean age was 44.2 (SD=11.7). The reportedethnicities were: White (n=16), Black-Caribbean (n=3), BlackAfrican (n=5), Black-Other (n=3), Indian (n=1), and other(n=2). Twenty-two patients were unemployed, three wereworking part-time, three were retired, and one was a student.The educational qualifications were: none (n=6), GCSE (n=10),AS/A-level (n=5), diploma (n=6), degree (n=1), postgraduatedegree (n=2). The diagnoses were: schizophrenia (n=24),schizo-affective disorder (n=4) and delusional disorder (n=2).Antipsychotic medication data were converted into chlorpro-mazine equivalents grouped into low (0–200 mg), medium(200–400 mg) and high (≥400 mg); one personwas not takingany medication, elevenwere on a low dose, fourteenwere on amedium dose and four were on a high dose. Seven patientswere taking clozapine, seventeen patients were taking otheratypical antipsychotics, and five people were on typicalantipsychotic medication. Five patients were being prescribedtwo different antipsychotic drugs.

The prevalence of insomnia in the persecutory delusionsgroup as assessed by the ISI was: 27% (n=8) severe clinicalinsomnia, 27% (n=8) clinical insomniaofmoderate severity, and30% (n=9) subthreshold insomnia. Only 17% (n=5) had noclinically significant insomnia. There was a high correlationbetween ISI and Sleep-50 scores, r=.78, pb .001. Sixty percent(n=18) of the persecutory delusions group scored abovethe Sleep-50 insomnia cut-off. Scores did not differ bymedication level on the ISI, F(2, 26)=.137, p=.872, or theSleep-50, F(2,26)=.350, p=.708.

4. Discussion

The rates of sleep difficulties in the community samplewereconsistent with the epidemiological literature; almost 30% hadsymptoms of insomnia and approximately 10% were in theclinical range. But the unique focus of the study was on apotential association between sleep difficulties and paranoid

283D. Freeman et al. / Schizophrenia Research 108 (2009) 280–284

thinking. The resultswere clear: higher levels of insomniawereassociated with higher levels of persecutory thinking. Con-firmation was provided by the high prevalence of insomnia inthe individualswith clinical paranoia. Insomnia ismost likely anoverlooked problem in psychiatric services for individuals withpersecutory delusions.

Sleep disturbance is already incorporated into a theore-tical account of persecutory delusions (Freeman et al., 2006),but its role had not been directly tested. In this study therelationship between sleep and paranoia was largely ac-counted for by levels of anxiety and depression. This isunsurprising; both paranoia and sleep difficulties are closelylinked with negative affect. Nevertheless the mediatingroutes between insomnia and paranoia require closer (andmore rigorous) examination. A second plausible route is viathe occurrence of perceptual anomalies. A lack of sleep maycause a puzzling internal state for the individual that, in thecontext of anxiety, is incorrectly attributed to externalthreat. Study of the mechanisms underlying insomnia inpatients with persecutory delusions is also needed; sleepdisturbance may be partly maintained by established insom-nia-related processes such as rumination, attention to sleep-related threat, and dysfunctional beliefs about sleep (Harveyet al., 2005).

The representativeness of the samples in the current studyis questionable; the community group was only a minority ofthe many people leafleted in the local postcodes, while theclinical group was of a small size. There was also a reliance onself-report assessments. The study focussed on a specificexperience (paranoid ideation), but it could be argued thatcompletion of a full diagnostic screening interview by thenon-clinical population would have provided information ofinterest. However the key limitation of the study is the cross-sectional design. The causal direction of the relationshipbetween insomnia and paranoia is unknown. It is plausiblethat the insomnia assessed is simply a consequence of livingwith paranoid fears, although a circular relationship betweeninsomnia, anxiety and paranoia is more probable. Long-itudinal studies of the relationships are clearly warranted. Apriority is the evaluation of well-established insomniainterventions (e.g. Espie, 2006; Harvey et al., 2007) forindividuals with delusions. These interventions will providea stronger test of the causal relationship between insomniaand paranoia and hold the promise of enhancing the efficacyof treatments for delusional beliefs.

Role of funding sourceFunding for this study was provided by a Fellowship awarded by the

Wellcome Trust to Dr. Daniel Freeman. TheWellcome Trust had no further rolein study design; in the collection, analysis and interpretation of data; in thewriting of the report; and in the decision to submit the paper for publication.

ContributorsDaniel Freeman designed the study, analysed the data and wrote the

paper. Katherine Pugh, Natasha Vorontsova, and Laura Southgate collectedthe data and commented upon the manuscript.

Conflict of interestThere were no conflicts of interest.

AcknowledgementThe research was funded by a Wellcome Trust Fellowship awarded to Dr.

Daniel Freeman.

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