Determining the level of sleepiness in the American population and its correlates Maurice M. Ohayon * Stanford Sleep Epidemiology Research Center, Stanford University, School of Medicine, 3430 W. Bayshore Road, Palo Alto, CA 94303, USA article info Article history: Received 7 March 2011 Received in revised form 3 June 2011 Accepted 10 June 2011 Keywords: Epidemiology Sleepiness Mood disorders Hypnotics Organic diseases Sleep disorders abstract Objective: To assess the prevalence, to determine the risk factors and to evaluate the impacts of excessive sleepiness in the general population. Method: It is a cross-sectional telephone study using a representative sample consisting of 8937 non- institutionalized individuals aged 18 or over living in Texas, New York and California. They repre- sented a total of 62.8 million inhabitants. The participation rate was 85.6% in California, 81.3% in New York and 83.2% in Texas. Interviews were managed by the Sleep-EVAL expert system. The questionnaire included questions on sleeping habits, life habits, health, DSM-IV mental disorders, DSM-IV and ICSD sleep disorders. Results: As many as 19.5% of the sample reported having moderate excessive sleepiness and 11.0% reported severe excessive sleepiness. Moderate excessive sleepiness was comparable between men and women but severe excessive sleepiness was higher in women (8.6% vs. 13.0%). Factors associated with moderate excessive sleepiness were sleeping 6 h or less per main sleep episode (OR:2.0); OSAS (OR:2.0); insomnia disorder (OR:2.4); Restless Legs Syndrome (OR: 1.8) major depressive disorder (OR: 1.7); anxiety disorder (OR:1.5) and use of tricyclic antidepressant (OR: 2.1) presence of heart disease (OR: 1.5), cancer (1.8) and chronic pain (1.3). Factors associated with severe excessive sleepiness were similar with the addition of being a woman (OR:1.5), alcohol dependence (OR: 1.4), bipolar disorder (OR: 2.1), use of over-the-counter sleeping pills (OR: 2.5), narcotic analgesics (OR: 3.4), Antidepressants (other than SSRI or tricyclic) and presence of gastro-esophageal reflux disease (OR:1.6). Sleepy individuals were twice as likely than non-sleepy participants to have had accidents while they were at the wheel of a vehicle during the previous year. Conclusions: Excessive sleepiness is highly prevalent in the American population. It was strongly asso- ciated with insufficient sleep and various sleep disorders as well as mental and organic diseases. Ó 2011 Elsevier Ltd. All rights reserved. 1. Introduction The problem of excessive sleepiness has gained greater aware- ness in the past two decades, as illustrated by the increasing number of epidemiological studies examining its prevalence in the general population. Yet, comparability between these studies remains hazardous: Few of them have used similar definitions to measure excessive sleepiness. Some studies have used a frequency criterion while others have used a severity criterion, which leads to different figures (Ohayon, 2008). Therefore, reported prevalences have ranged from a low of 3.9% (Rockwood et al., 2001) to a high of 32% (Asplund, 1996). There is still little information regarding associated factors with daytime sleepiness. Some epidemiological studies have reported an association with poor sleep hygiene (Hublin et al., 1996; Ohayon et al., 1997), work conditions (Ohayon et al., 1997, 2010a, 2010b), psychotropic medication (Hublin et al., 1996; Ohayon et al., 1997; Nugent et al., 2001), sleep-disordered breathing (Ohayon et al., 1997; Hublin et al., 1996; Nugent et al., 2001; Bixler et al., 2005), psychiatric disorders (Ford and Kamerow, 1989; Breslau et al., 1996; Hublin et al., 1996; Ohayon et al., 1997) and physical illnesses (Hublin et al., 1996; Ohayon et al., 1997; Nugent et al., 2001). Unlike insomnia, excessive sleepiness is not a diagnosis; it can be an essential or an associated symptom of a sleep disorder such as for hypersomnia and obstructive or central sleep apnea syndrome. Or, it can be a consequence of a sleep disorder such as for insomnia. However, implications for individuals with excessive sleepiness can be dramatic; only a few seconds of lack of concentration may be enough to injury oneself or someone else. Surprisingly, almost no epidemiological studies have questioned the participants about the impact of excessive sleepiness on their daytime functioning. The present study aims: 1) to assess the prevalence of excessive sleepiness in the general population of three of the most populated * Tel.: þ1 650 494 1137; fax: þ1 650 947 9813/650 493 1225. E-mail address: [email protected]. Contents lists available at ScienceDirect Journal of Psychiatric Research journal homepage: www.elsevier.com/locate/psychires 0022-3956/$ e see front matter Ó 2011 Elsevier Ltd. 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0022-3956/$ e see front matter � 2011 Elsevier Ltd.doi:10.1016/j.jpsychires.2011.06.008
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a b s t r a c t
Objective: To assess the prevalence, to determine the risk factors and to evaluate the impacts of excessivesleepiness in the general population.Method: It is a cross-sectional telephone study using a representative sample consisting of 8937 non-institutionalized individuals aged 18 or over living in Texas, New York and California. They repre-sented a total of 62.8 million inhabitants. The participation rate was 85.6% in California, 81.3% in NewYork and 83.2% in Texas. Interviews were managed by the Sleep-EVAL expert system. The questionnaireincluded questions on sleeping habits, life habits, health, DSM-IV mental disorders, DSM-IV and ICSDsleep disorders.Results: As many as 19.5% of the sample reported having moderate excessive sleepiness and 11.0%reported severe excessive sleepiness. Moderate excessive sleepiness was comparable between men andwomen but severe excessive sleepiness was higher in women (8.6% vs. 13.0%). Factors associated withmoderate excessive sleepiness were sleeping 6 h or less per main sleep episode (OR:2.0); OSAS (OR:2.0);insomnia disorder (OR:2.4); Restless Legs Syndrome (OR: 1.8) major depressive disorder (OR: 1.7);anxiety disorder (OR:1.5) and use of tricyclic antidepressant (OR: 2.1) presence of heart disease (OR: 1.5),cancer (1.8) and chronic pain (1.3). Factors associated with severe excessive sleepiness were similar withthe addition of being a woman (OR:1.5), alcohol dependence (OR: 1.4), bipolar disorder (OR: 2.1), use ofover-the-counter sleeping pills (OR: 2.5), narcotic analgesics (OR: 3.4), Antidepressants (other than SSRIor tricyclic) and presence of gastro-esophageal reflux disease (OR:1.6). Sleepy individuals were twice aslikely than non-sleepy participants to have had accidents while they were at the wheel of a vehicleduring the previous year.Conclusions: Excessive sleepiness is highly prevalent in the American population. It was strongly asso-ciated with insufficient sleep and various sleep disorders as well as mental and organic diseases.
� 2011 Elsevier Ltd. All rights reserved.
1. Introduction
The problem of excessive sleepiness has gained greater aware-ness in the past two decades, as illustrated by the increasingnumber of epidemiological studies examining its prevalence in thegeneral population. Yet, comparability between these studiesremains hazardous: Few of them have used similar definitions tomeasure excessive sleepiness. Some studies have used a frequencycriterion while others have used a severity criterion, which leads todifferent figures (Ohayon, 2008). Therefore, reported prevalenceshave ranged from a low of 3.9% (Rockwood et al., 2001) to a high of32% (Asplund, 1996). There is still little information regardingassociated factors with daytime sleepiness. Some epidemiologicalstudies have reported an association with poor sleep hygiene(Hublin et al., 1996; Ohayon et al., 1997), work conditions (Ohayon
493 1225.
All rights reserved.
M, Determining the level ofsychires.2011.06.008
et al., 1997, 2010a, 2010b), psychotropic medication (Hublin et al.,1996; Ohayon et al., 1997; Nugent et al., 2001), sleep-disorderedbreathing (Ohayon et al., 1997; Hublin et al., 1996; Nugent et al.,2001; Bixler et al., 2005), psychiatric disorders (Ford andKamerow, 1989; Breslau et al., 1996; Hublin et al., 1996; Ohayonet al., 1997) and physical illnesses (Hublin et al., 1996; Ohayonet al., 1997; Nugent et al., 2001).
Unlike insomnia, excessive sleepiness is not a diagnosis; it canbe an essential or an associated symptom of a sleep disorder such asfor hypersomnia and obstructive or central sleep apnea syndrome.Or, it can be a consequence of a sleep disorder such as for insomnia.However, implications for individuals with excessive sleepiness canbe dramatic; only a few seconds of lack of concentration may beenough to injury oneself or someone else. Surprisingly, almost noepidemiological studies have questioned the participants about theimpact of excessive sleepiness on their daytime functioning.
The present study aims: 1) to assess the prevalence of excessivesleepiness in the general population of three of the most populated
sleepiness in the American population and its correlates, Journal of
M.M. Ohayon / Journal of Psychiatric Research xxx (2011) 1e62
U.S. states: California, New York and Texas; 2) to examine theassociations between excessive sleepiness, mental disorders, sleepdisorders and organic illnesses; 3) to determine the risk factors forexcessive sleepiness and 4) to evaluate the impacts of excessivesleepiness on daytime functioning and help-seeking behaviors.
2. Methods
2.1. Sample
The study has been ongoing since 2003 (Ohayon et al., 2010b).The target population was individuals aged 18 years and olderliving in the states of California, New York and Texas (USA). A totalof 8937 individuals were interviewed by telephone. They wererepresentative of the general population of these three states (3243subjects in California, 3445 subjects in New York and 2249 subjectsin Texas). These three states represented a total of 62.8 millioninhabitants. The participation rate was 85.6% in California, 81.3% inNew York and 83.2% in Texas. The sample used in this study is thefirst wave of a longitudinal cohort currently in its fourth wave.
2.2. Procedures
In the first stage, telephone numbers were randomly selectedproportionally to the population size of each county in California,New York and Texas. The selectionwas donewithin each state usinga computerized residential phone book. In the second stage, duringthe telephone contact, the Kish method (Kish, 1965) was used toselect one respondent per household. This method allowed for theselection of a respondent based on age and gender to maintaina sample representative of these two parameters. If the householdmember chosen declined to participate, the household was drop-ped and replacedwith another number from the same area, and theprocess was repeated.
Interviewers explained the goals of the study to potentialparticipants. They requested verbal consent before conducting theinterview. The participants had the option of calling the principalinvestigator if they wanted further information. The study wasreviewed by the Stanford University Institutional ReviewBoards (IRB).
Excluded from the study were subjects who were not fluent inEnglish (or Spanish), who suffered from a hearing or speechimpairment or who had an illness that precluded them from beinginterviewed. Phone numbers were dropped and replaced only aftera minimum of 10 unsuccessful dial attempts weremade at differenttimes and on different days, including weekends. An added-digittechnique; that is, increasing the last digit of a number by one,was employed to control for unlisted telephone numbers. The finalsample included 21.4% unlisted telephone numbers.
The interviews lasted on average 74.5 (�37.8) min. An interviewcould be completed with more than one telephone call when itexceeded 60 min or at the request of the participant. Participantsanswered an average of 308 questions. The shortest interviews had110 questions and the longest had 630 questions. The projectmanager or the team leaders also called nearly all the participantswho completed the interview. During this 6e8 min call, they askeda series of random questions related to the interview and also askedthe participants how satisfied they were with the interviewer.Interviewers were supervised by two or three team leaders witha ratio of one team leader for every 6 interviewers.
3. Instrument
Interviewers used the Sleep-EVAL knowledge-based expertsystem (Ohayon, 1994, 1999) to conduct the interviews. This
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computer software is specially designed to administer question-naires and conduct epidemiological studies in the generalpopulation.
The system is composed of a non-monotonic, level-2 inferenceengine, two neural networks, a mathematical processor, theknowledge base and the base of facts. Simply put, the interviewbegins with a series of questions asked of all the participants.Questions were read aloud by the interviewer as they appeared onthe screen. These questions were either closed-ended (e.g., yes/no,five-point scale, multiple choice) or open-ended (e.g., duration ofsymptom, description of illness).
Once this information was collected, the system began thediagnostic exploration of mental disorders. On the basis ofresponses provided by a subject to this questionnaire, the systemformulated an initial diagnostic hypothesis that it attempted toconfirm or reject by asking supplemental questions or by deduc-tions. Concurrent diagnoses are allowed in accordance with theDSM-IV (APA, 2000) and the Classification of Sleep Disorders orICSD (AASM, 1997). The system terminated the interview once alldiagnostic possibilities were exhausted.
The differential process is based on a series of key rules allowingor prohibiting the co-occurrence of two diagnoses. The question-naire of the expert system is designed such that the decision aboutthe presence of a symptom is based upon the interviewee’sresponses rather than on the interviewer’s judgment. Thisapproach has proved to yield better agreement between lay inter-viewers and psychiatrists on the diagnosis of minor psychiatricdisorders (Lewis et al., 1992). The system has been tested in variouscontexts, in clinical psychiatry and sleep disorders clinics (Ohayon,1995; Ohayon et al., 1999).
4. Variables
Sleepiness was assessed according to its severity (on a five-point scale ranging from not at all to extremely), frequency ina day, frequency in a week, moment of the last episode, period inthe day when sleepiness occurred, situations and intensity whensleepiness occurred (at work, during daily activities, at school,when visiting friends or relatives, during a conversation, in quietsituations (watching TV, reading, relaxing), as a car passenger, asa driver, when using public transportation), evolution of exces-sive sleepiness since it first appeared, medical consultationrelated to sleepiness and impacts of sleepiness on daytimefunctioning.
4.1. Other variables included
Sociodemographic information: age, gender, race, maritalstatus, occupation, education level, number of children, income.
Medical information: 1) Consultations in the previous year:number and specialty of consulted physician(s); 2) Hospitali-zations in the previous year: number, duration and motives; 3)Description of illnesses; 4) Medications and indications; 5)Pain: sites of pain; frequency, intensity and duration; treat-ment; causes of pain; 6) Menopausal status for women; 7)Health quality; 8) Weight, height, blood pressure; 9) Medicalinsurance.
Life habits: use and quantity of alcohol, drugs (other thanmedication), tobacco and caffeine; frequency of physical exercise.
Mental disorder diagnoses were assessed according to DSM-IVclassification respecting positive and differential diagnosisprocesses. Sleep disorders were assessed according to the DSM-IVand ICSD classifications. ICD-10 was used for the classification oforganic diseases.
sleepiness in the American population and its correlates, Journal of
Odds ratios (OR) adjusted for age, gender and occupation.*p < 0.001; **p < 0.005; ***p < 0.01; ****p < 0.05.
M.M. Ohayon / Journal of Psychiatric Research xxx (2011) 1e6 3
5. Analyses
A weighting procedure was applied to correct for disparities inthe geographical, age and gender distribution between the sampleand the populations of California, New York and Texas. Results werebased onweighted n values and percentages. ANOVAwith post-hoccomparisons were used to analyze sleep duration. Logistic regres-sions were used to compute the odds ratios (OR) associated withexcessive sleepiness.
6. Results
The participants in the sample were aged between 18 and 97years; 54.1% were women.Retired individuals represented 17.1% ofthe sample; students 6.8%; daytime workers 39.6%; and shift-workers 24.3% (i.e., working outside regular daytime hoursbeyond 07:00 to 18:00 h).
A total of 19.5% (95% CI ¼ 18.7%e20.3%) of the sample reportedmoderate excessive sleepiness and 11% (95% CI ¼ 10.3%e11.7%)reported severe excessive sleepiness. Prevalence of moderateexcessive sleepiness was similar between men and women. Severeexcessive sleepiness, however, was higher in women (13.0%) thanin men (8.6%; OR 1.5) (Table 1).
Individuals with severe excessive sleepiness reported morefrequently being sleepy every day (61.9%) than people withmoderate excessive sleepiness (44.7%) whereas the latter weremore likely to report a frequency of 3e4 days a week (40.6%) thanthose with severe excessive sleepiness (24.3%; p < 0.0001).Excessive sleepiness was mostly chronic, lasting for at least oneyear in 87.9% of individuals with moderate excessive sleepiness andin 80.7% of individuals with severe excessive sleepiness.
6.1. Association with sleep disorders
The prevalence of severe excessive sleepiness was four timeshigher and moderate excessive sleepiness twice as high in indi-viduals sleeping less than 6 h per night compared to the prevalenceobserved in individuals sleeping between seven and 8 h per night(Table 2). Individuals sleeping between six and 7 h were also atgreater risk of severe daytime sleepiness.
Individuals with DSM-IV insomnia disorders were 2.4 timesmore likely to report moderate excessive sleepiness and 3.8 times
Table 1Prevalence of excessive sleepiness and sociodemographic characteristics.
Please cite this article in press as: Ohayon MM, Determining the level ofPsychiatric Research (2011), doi:10.1016/j.jpsychires.2011.06.008
more likely to report severe excessive sleepiness than individualswithout insomnia disorder (Table 2).
Individuals with Obstructive Sleep Apnea Syndrome (OSAS) alsohad significantly higher prevalence of moderate and severeexcessive sleepiness than non-OSAS subjects. Similarly, the preva-lence of moderate and severe excessive sleepiness was higher inindividuals with Restless Legs Syndrome. The prevalence ofnarcolepsy in the sample was 0.056% (56 per 100,000).
6.2. Association with psychiatric disorders
The prevalence of severe excessive sleepiness was higher inindividualswith aMajor Depressive Disorder; a Bipolar Disorder; anAnxiety Disorder; or alcohol dependence. The prevalence ofmoderate excessive sleepiness was higher only in individuals witha Major Depressive Disorder or an Anxiety Disorder. Drug depen-dence, adjustment disorder, eating disorder and psychotic disorderwerenot significantlyassociatedwith excessive sleepiness (Table 2).
6.3. Association with medications
Different types of psychotropic medications were examined toverify if they had any associationwith excessive sleepiness. As seenin Table 3, tricyclic antidepressants, other type of antidepressants
sleepiness in the American population and its correlates, Journal of
Table 3Prevalence of excessive sleepiness and association with medication.
Adjusted for age, gender and occupation.*p < 0.001; **p < 0.005; ***p < 0.01; ****p < 0.05.
M.M. Ohayon / Journal of Psychiatric Research xxx (2011) 1e64
(i.e, other than SSRI or tricyclic), narcotic analgesics, over-the-counter (OTC) sleeping pills and medication for migraine/head-ache were associated with severe excessive sleepiness afteradjusting for age, gender, occupation and psychiatric disorders. Asfor moderate excessive sleepiness, only tricyclic antidepressantswere positively associated. Stimulants, hypnotics and anxiolyticswere not significantly associated with excessive sleepiness.
6.4. Association with organic diseases
Most frequent organic diseases reported by the participantswere examined. Only individuals with chronic pain and those withgastro-esophageal reflux disease were more likely to report severeexcessive sleepiness. On the other hand, heart disease, hypercho-lesterolemia, cancer and chronic pain were associated withmoderate excessive sleepiness (Table 4).
Fig. 1 presents a Venn’s diagram illustrating the associationsbetween excessive sleepiness (moderate or severe), sleep disorders,mental disorders and organic diseases. As seen, as many as 4.7% ofthe sample had the four conditions; i.e., at least one mentaldisorder and one sleep disorder and one organic disease accom-panied bymoderate or severe excessive sleepiness. Also, 9.1% of thesample had a sleep disorder accompanied by an organic disease andexcessive sleepiness.
6.5. Consequences of excessive sleepiness
Individuals with severe excessive sleepiness more frequentlyreported that the sleepiness interfered with social activities thandid those with moderate excessive sleepiness (35.7% vs. 21%;
Please cite this article in press as: Ohayon MM, Determining the level ofPsychiatric Research (2011), doi:10.1016/j.jpsychires.2011.06.008
p < 0.01). Interference with daily activities was also more frequentin subjects with severe excessive sleepiness (38.8%) compared tothose with moderate excessive sleepiness (22.0%; p < 0.005).Interference with professional activities was reported by 28.9% ofindividual with severe excessive sleepiness comparedwith 14.6% inthosewithmoderate excessive sleepiness (p< 0.001). Finally, 23.3%of individuals with severe excessive sleepiness reported interfer-ence with family relationships compared to 14.1% of individualswith moderate excessive sleepiness (p ¼ 0.05).
Sleepiness was considered a problem by 45.5% of individualswith severe excessive sleepiness but only 14% sought medicaladvice for it. Similarly, 30.7% of individuals with moderate exces-sive sleepiness considered it to be a problem but only 10.7% hadconsulted for it.
Proportion of road ormachinery accidents while the subject wasat the wheel was also higher in subjects with moderate (7.7%) orsevere excessive sleepiness (7.4%) compared with the non-sleepydrivers (4.7%; p < 0.01).
More than 40% of subjects with severe excessive sleepiness(42.4%) took sick leaves fromwork in the preceding 12months. Thiswas the case for 35.1% of individuals with moderate excessivesleepiness and for 26.6% of non-sleepy workers (p < 0.0001). Inaddition of being more likely to take sick leaves, individuals withsevere excessive sleepiness took more days of sick leaves (mean of11.8 days) than non-sleepy individuals (8.1 days; p < 0.005).
7. Discussion
This study aimed to examine the characteristics and risk factorsassociated with excessive sleepiness in a representative sample ofthree American states: California, New York and Texas. One of the
sleepiness in the American population and its correlates, Journal of
Fig. 1. Associations between excessive sleepiness, mental disorders, sleep disorders and organic diseases in the whole sample. Legend: Rates are prevalence. 24.8% of the samplehad none of the four conditions. Sleep disorders included Insomnia Disorders, Hypersomnia Disorders, Circadian Rhythm Sleep Disorders, Restless Legs Syndrome and Behaviorally-Induced Insufficient Sleep Syndrome. Mental disorders include DSM-IV psychotic, mood, anxiety, eating disorders and alcohol/drug dependence. Organic diseases also includedchronic pain.
M.M. Ohayon / Journal of Psychiatric Research xxx (2011) 1e6 5
most astonishing findings is the high rate of sleepiness in thissample: 19.5% reported moderate excessive sleepiness and 11%severe excessive sleepiness, which is 10% higher than the preva-lence reported in a European sample using the same methodology(Ohayon et al., 2002).
There are few studies that have examined excessive sleepinessin terms of duration, frequency and severity (Ohayon et al., 1997).As our results show, excessive sleepiness is a symptom that ismostly chronic: more than 80% have it for at least one year.Furthermore, individuals with severe excessive sleepiness tend toexperience it on a daily basis. These results are unique in the sensethat epidemiological studies on excessive sleepiness have studiedthe frequency or the severity of the symptom but not the twotogether. Therefore, the severity is not only a matter of the intensityof the sleepiness but also how often it occurs. Consequently,moderate and severe excessive sleepiness were analyzed separatelyto verify if the characteristics and associated risk factors werethe same.
We found several differences between moderate and severeexcessive sleepiness: moderate excessive sleepiness was unrelatedto occupation and gender and showed little variability with age,while severe excessive sleepiness affected women more frequentlyand more frequently younger subjects. This distinction could partlyexplain why some studies have found differences between age andgender and other studies have not (Gislason et al., 1988; Ohayonet al., 1997, 2002; Nugent et al., 2001). In this study, excessivesleepiness had to be present at least three days per week, had to bemoderate or severe and had to be present for at least one month.
Excessive sleepiness can be a consequence or an associatedfeature of several sleep disorders (Hublin et al., 1996; Ohayon et al.,1997; Nugent et al., 2001; Ulfberg et al., 2007; Benediktsdottir et al.,2010), insomnia disorders and obstructive sleep apnea being two
Please cite this article in press as: Ohayon MM, Determining the level ofPsychiatric Research (2011), doi:10.1016/j.jpsychires.2011.06.008
common conditions in which sleepiness can occur. Not surprisingly,we found that these two disorders are highly associated withexcessive sleepiness as well as was Restless Legs Syndrome. Thedifference from other studies is that ours shows a higher probabilityof severeexcessive sleepiness in individuals sufferingthesedisorders.
We also found higher likelihoods of excessive sleepiness inindividuals sleeping less than 6 h per night. It should be noted thatit is not a diagnosis of insufficient sleep syndrome; short sleepersmay well have other disorders that explain the short sleep.However, the association between short sleep and excessivesleepiness has been reported numerous times (Kaneita et al., 2005;Ohayon and Vecchierini, 2005; Bartlett et al., 2008). Interestinglyalso, in one of our previous studies (Ohayon et al., 2002) conductedin European countries, those with a higher prevalence of excessivesleepiness(the United Kingdom and Germany) were also thecountries with shorter sleep durations.
Associations between excessive sleepiness andmental disordershave been previously reported (Ford and Kamerow, 1989; Breslauet al., 1996; Hublin et al., 1996; Ohayon et al., 1997). In our study,we indeed found a higher likelihood of moderate or severe exces-sive sleepiness among individuals with Major Depressive Disorderand Anxiety Disorders. However, individuals with Bipolar Disordersand those with alcohol dependence were more likely to reportsevere excessive sleepiness but not moderate excessive sleepiness.These associations are interesting; unlike insomnia symptoms,excessive sleepiness is not an associated symptom of any anxietydisorder; hypersomnia, however, is an associated symptom ofmood disorders. But excessive sleepiness and hypersomnia are notthe same: the first refers to sleep propensity during wakefulnesswhile the latter refers to an excessive amount of sleep. One possibleexplanation could be that excessive sleepiness occurs in mentaldisorders as a consequence of insomnia symptoms.
sleepiness in the American population and its correlates, Journal of
M.M. Ohayon / Journal of Psychiatric Research xxx (2011) 1e66
We also have examined the association between different typesof medication and the report of excessive sleepiness. To ourknowledge, these associations have never been examined in pastgeneral population surveys. We found that people taking sometypes of antidepressants, over-the-counter sleeping pills, narcoticanalgesics and headache/migraine medication were more likely toexperience severe excessive sleepiness. Over-the-counter sleepingpills are very popular in the American population. In our sample,5.1% reported weekly use of such medication. The problem is thatmost of these medications include Diphenhydramine or Doxyl-amine, which are potent sedatives with a long half-life. Therefore itis not surprising to find that these users were more likely toexperience severe excessive sleepiness in the daytime. Tricyclicantidepressants are also known for their sedative properties;drowsiness is a common side effect. Consequently, it was expectedthat individuals taking these medications would report somedegree of sleepiness.
This study was also the first to examine the consequences ofexcessive sleepiness on the daily activities of sleepy participants. Asexpected, individuals with severe excessive sleepiness were muchmore likely than those with moderate excessive sleepiness toreport interference in various spheres of their life. Surprisingly,although many sleepy individuals considered their sleepiness asa serious problem,most of them had not consulted about it. We alsofound that sleepy individuals were nearly twice as likely to havehad accidents while they were at the wheel of a vehicle than non-sleepy participants. Sleepiness or drowsiness has often beenreported as a major factor in road accidents (Philip et al., 2010;Drake et al., 2010).
In summary, excessive sleepiness is highly prevalent in the U.S.general population. The conditions and disorders that could beresponsible for the excessive sleepiness are varied and the inter-actions are complex: 66% of individuals with excessive sleepinesshave at least two categories of diseases or disorders (psychiatric,sleep or organic) associated with the sleepiness. Health care policymakers need to know the outcomes of excessive sleepiness not onlyin financial costs but also in number of lost lives.
Role of funding source
Funding for this study was provided by Cephalon Inc. The sup-porting entity had no role in the design and conduct of the study(collection, management, analysis) nor in the interpretation of thedata. The supporting entity has not seen themanuscript and had norole in the decision to submit the paper for publication.
The author had full access to all of the data in the study andtakes responsibility for the integrity of the data and the accuracy ofthe data analysis.
Contributors
No contributor.
Conflict of interestNone.
Acknowledgement
This study was supported by a grant from and developed intheory with Cephalon Inc.
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