Motor vehicle crashes were the

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1 Article Sleep, sleepiness and motor vehicle accidents: a national survey Abstract Objective: To assess the role of sleeprelated factors, ethnicity and socioeconomic deprivation in self-reported motor vehicle accidents while driving, after controlling for gender, age and driving exposure. Methods: Mail survey to a random electoral roll sample of 10,000 people aged years, stratified by age decades and ethnicity (71% response rate). The analytical sample included 5,534 current drivers (21.6% Maori men, 21.2% Maori women, 30% non-maori men, 27.2% non- Maori women). Results: Multiple logistic regression analyses revealed the following independent risk factors for accident involvement while driving (last three years): being younger; higher average weekly driving hours; never/rarely getting enough sleep (OR=1.26, 95% CI ); reporting any chance of dozing in a car while stopped in traffic (Epworth Sleepiness Scale question 8, OR=1.52, 95% CI ); and among women, being non-maori. Total Epworth score was not significantly related to reported accident involvement. Conclusions: Chronic sleep restriction, and any likelihood of dozing off at the wheel of a motor vehicle, were significant independent predictors of self-reported involvement in all types of motor vehicle accidents, not only those identified as fatigue-related. The Epworth Sleepiness Scale alone is not a reliable clinical tool for identifying individuals at higher risk of crashes. Implications: Factors relating to chronic sleepiness were as important as established demographic risk factors for self-reported motor vehicle accident involvement among year-old drivers. The findings reinforce the need for multi-faceted campaigns to reduce sleepy driving. (Aust N Z J Public Health 2005; 29: 16-21) Philippa H. Gander, Nathaniel S. Marshall Sleep/Wake Research Centre, Massey University, Wellington, New Zealand Ricci B. Harris, Papaarangi Reid Eru Pomare Maori Health Research Centre, Department of Public Health, Otago University at Wellington School of Medicine and Health Sciences, New Zealand Motor vehicle crashes were the leading cause of Maori mortality in the year age range in New Zealand (NZ) for the years For non-maori in the same age range, motor vehicle accidents were the second leading cause of death after the cancers. 1 The NZ Land Transport Authority focuses on three primary safety issues in its national strategy to reduce road crashes: excessive speed, alcohol and failure to wear safety belts. The present study addresses an additional contributing factor to road crashes that is less well understood in this country, namely driver sleepiness. Fatigue was identified as a contributing factor in 12% of fatal crashes on New Zealand roads in 2003, making it the sixth most common factor (Tui Patterson, LTSA, personal communication). Overseas studies suggest that sleepiness is a contributing factor in 6-30% of all car crashes, with estimates varying according to a range of factors such as the type of road, the severity of the crashes considered and how the role of sleepiness was determined. 2-7 These studies show that the relative frequency of such crashes rises and falls in parallel with sleep tendency, with a large peak in the early hours of the morning and a smaller secondary peak in the mid-afternoon. The high physiological sleep drive in the early hours of the morning coincides with darkness and low traffic volumes, which arguably make the driving environment more soporific. A recent population-based casecontrol study in the Auckland region estimated that, by reducing the number of drivers who drive sleepy, or with five hours or less of sleep, or who drive between 2 and 5 am, it may be possible to reduce the rate of injury crashes by as much as 19%. 8 Excessive sleepiness is also considered to be the cause of the increased crash risk found among people who suffer from Obstructive Sleep Apnoea Syndrome (OSAS), a common treatable sleep disorder Two recent studies have shown that effective treatment of OSAS reduces crash risk to the same level as that of matched controls. 12, 13 Younger drivers (under 25 years) are reported to be more likely to crash due to falling asleep at the wheel 2,5,8 and are much more likely to crash in general. 14 To help clarify the role of driver sleepiness in road accidents in New Zealand, we included questions addressing average weekly driving hours and history of motor vehicle accidents while driving as part of a national survey of sleep habits and OSAS risk factors. 15 The survey included year olds, because this covers the age range in which OSAS prevalence peaks 16 and includes the bulk of the driving population. Methods Questionnaire design The study was approved by the Wellington Regional Ethics Committee. A short questionnaire (two A-4 sides) was developed Submitted: March 2004 Revision requested: July 2004 Accepted: September 2004 Correspondence to: Dr Philippa Gander, Sleep/Wake Research Centre, Research School of Public Health, Massey University, Wellington, Private Box 756, Wellington, New Zealand. Fax: ; p.h.gander@massey.ac.nz 16 AUSTRALIAN AND NEW ZEALAND JOURNAL OF PUBLIC HEALTH 2005 VOL. 29 NO. 1

2 Sleepiness and motor vehicle accidents through an iterative process of pre-testing and piloting. 15 The 17 questions sought information on: demographics, usual sleep, the Epworth Sleepiness Scale, 17 risk factors for OSAS, current treatment for common OSAS co-morbidities, alcohol consumption and smoking habits, eligibility for a Community Services Card (which provides special subsidies for access to health care), average weekly driving hours and motor vehicle accident history (see Appendix A). Classification of ethnicity was a key concern, given that the survey sought to understand and reduce disparities between Maori and non-maori health. 15 The questionnaire included the 1996 NZ Census question on ethnicity, which allows people to self-identify with multiple ethnic groups. Those who ticked Maori, with or without another ethnic identification, were coded as Maori, and all the analyses presented here were based on self-identified ethnicity. A small pilot study (600 participants from the Wellington region) found that, among participants who identified Maori as one of their ethnic affiliations, 91% were registered as being of Maori descent on the electoral roll. 15 The question on accident involvement, taken from a survey of UK car drivers, 4 was how many times during the last 3 years have you been involved in a motor vehicle accident where you were driving?. For the analyses presented here, responses were dichotomised (accident/no accident). Based on their home addresses, participants were also assigned a small area deprivation score (NZDep96) from 1 (live in the least deprived 10% of Census meshblocks) to 10 (live in the most deprived 10% of meshblocks). 18,19 Sampling strategy A stratified random sample was taken from the electoral roll, with the aim of recruiting equal numbers of Maori and non-maori participants and equal numbers in each 10-year age group from 30 to 59 years. 15 This design was chosen to provide equal explanatory power for Maori and non-maori, which is necessary for research that seeks to understand and address the causes of disparities by ethnicity. Maori represented about 15% of the population at the time of the study. 20 Based on response rates in the pilot survey, study packages were mailed in April 1999 to an age-stratified sample of 5,500 registered electors of Maori descent and 4,500 non-maori registered electors. The study package included an information letter (tailored for Maori or non-maori participants), the questionnaire, a paper tape measure (for measuring neck circumference) and a stamped, addressed return envelope. Participants could also call a toll-free number to ask questions and to respond by telephone if they so wished. A subset of 137 participants in the pilot study answered the questionnaire by both mail and telephone (at an interval of about five weeks). This confirmed that there were no systematic differences between telephone and mail responses. Intensive follow-up was undertaken. At approximately twoweekly intervals, remaining non-responders received a postcard reminder, then a complete new study package, and then telephone follow-up was undertaken for those for whom telephone numbers could be found. As an incentive, all participants were offered the opportunity to go into a draw for a mystery holiday weekend. A total of 7,048 responses were received (response rate for the Maori sample 67%, for the non-maori sample 77%, excluding those who were ineligible because they were deceased or had left New Zealand). Of these participants, 574 did not drive a motor vehicle at the time of the study and were therefore excluded from the analyses presented here. A further 1,106 participants did not provide complete information on all the variables of interest for the multivariate analysis (see below), which is thus based on data from 5,368 participants. Data management and analysis Data were double entered and anomalous responses and outliers were individually evaluated according to a set of rules to ensure consistency. Analyses were undertaken in SAS v.8 (SAS Institute; NC, USA). Univariate relationships were examined (chi square analyses) between reported accident involvement and a series of dependent variables chosen on an a priori basis as possible predictors of accident involvement (see Table 2). Those variables that showed significant univariate relationships were then entered into a logistic multiple regression model, to identify significant independent predictors of reported accident involvement. To test whether the profile of risk factors might be different for Maori and non-maori, a logistic multiple regression model was run that included interactions between ethnicity and each of the other dependent variables. The only significant interaction was between ethnicity and gender. Pearson s correlation coefficients were used to check for colinearity between the dependent variables. The strongest relationship was between the variables categorising how often people got enough sleep and woke refreshed (rho=0.619, p<0.0001). The waking refreshed variable did not show a significant univariate relationship with accident involvement (see Table 2), so it was not included in the multivariate model. The remaining significant correlations ranged from to 0.350, indicating that co-linearity was not an issue. 21 Results Participants The sample included for analysis was constituted as follows: Maori men 21.6%, Maori women 21.2%, non-maori men 30.0%, non-maori women 27.2%. The age distribution was 31.9% aged years, 35.2% aged years and 32.9% aged years. The participants were not equally distributed across each of the 10 categories of the socio-economic deprivation index (chi-square p<0.001), with the smallest proportion being in decile 5 (9.0% of sample). This v-shaped distribution results from the sampling strategy, which recruited approximately equal numbers of Maori, who are over-represented in the more deprived deciles, and non- Maori, who are over-represented in the less deprived deciles. 19 Table 1 shows the demographic breakdown of the 644 participants (12.3%) who reported being the driver in at least one accident in the preceding three years. Accidents were reported disproportionately by men, by younger drivers and by non-maori participants VOL. 29 NO. 1 AUSTRALIAN AND NEW ZEALAND JOURNAL OF PUBLIC HEALTH 17

3 Gander et al. Article Logistic regression Table 2 summarises all the dependent variables considered for inclusion in the multiple logistic regression model, and their univariate relationships with self-reported accident involvement. Since subjective sleepiness is recognised as situational, 22 the component question of the Epworth sleepiness score that deals specifically with sleepiness at the wheel of a car was also considered. Question 8 asks the likelihood of dozing in a car while stopped for a few minutes in traffic. Those variables that showed significant relationships in Table 2 were entered into the multiple logistic regression models. There was a significant interaction between ethnicity and gender, so this interaction term was also included in the final model, which is summarised in Table 3. The significant interaction resulted from the fact that Maori women were less likely than non-maori women to report crash involvement (9.7% versus 12.8%, χ 2 (1)=6.32, p=0.0120). In contrast, there was no difference in crash reporting between Maori men and non-maori men (12.2% versus 13.9%, χ 2 (1)=1.50, p=0.2212). Factors that independently increased the likelihood of reporting an accident were: being younger; driving more hours per week; having any chance of dozing while stopped for a few minutes in traffic; never/rarely getting enough sleep; and having a neck size in the smallest quartile, compared with either the third or fourth quartile. For non-maori versus Maori women, the independent OR=1.49 (95% CI ). For men, the difference by ethnicity was not significant (OR=1.14, 95% CI ). Within ethnic groups, the difference by gender was not significant (for Maori, OR=0.99, 95% CI ; for non-maori, OR=1.29, 95% CI ). Conclusions This large cross-sectional survey suggests that chronic sleep restriction and self-reported sleepiness in a motor vehicle may be as important as the traditionally recognised risk factors for motor vehicle accident involvement, namely the amount of time spent driving, age and gender. Demographic factors As expected, higher average weekly driving hours increased the likelihood of reporting an accident, and men were significantly more likely to report accidents than were women. Accident risk decreased with each decade of age, although the age range of participants (30-60 years) probably reduced the magnitude of the age-related effect. 14 Table 1: Percentage of participants reporting accident involvement over three years. Years Maori Maori Non-Maori Non-Maori Total men women men women Total Maori were less likely than non-maori to report being involved in motor vehicle accidents. This seems somewhat surprising, given that for the years , Maori aged years were 1.5 times more likely than non-maori to die and 1.7 times more likely to be admitted to hospital due to a motor vehicle crash. 1 These figures are also likely to underestimate the differences, due to the methods used to classify ethnicity during this time. Several factors may have contributed to this discrepancy. First, statistics for crashrelated injuries and deaths include passengers, whereas the present study related only to drivers. Second, routinely collected crash statistics also do not capture many of the less severe accidents that appear to have been reported in this study (see below). This would contribute to the discrepancy if Maori are over-represented in more severe accidents and under-represented in less severe accidents. Socio-economic deprivation, as measured by NZDep96, was not a significant independent predictor of accident involvement. The sensitivity of the index is limited by the fact that it is based on small areas (Census mesh blocks), rather than individual characteristics. Nevertheless, numerous health-related measures, including injury-related mortality, are significantly related to the index. 19 Eligibility for a Community Services Card was not a significant independent predictor of accident involvement, but this is arguably a rather crude measure of individual socioeconomic status. Sleep-related factors People who reported never or rarely getting enough sleep were more likely to report accidents than those who reported often/ always getting enough sleep (OR=1.26). This is consistent with previous reports of significant relationships between self-reported sleep difficulties and fatal occupational accidents, 23 or selfreported automobile accidents attributed to being tired. 24 Reporting any chance (as opposed to no chance) of dozing in a car while stopped for a few minutes in traffic was an independent risk factor for crash reporting (OR=1.52). However, total Epworth Table 3: Multiple logistic regression: independent odds ratios for reporting accident(s) versus no accident. Variable OR 95% CI p Age yrs vs yrs yrs vs yrs Average weekly driving hours hrs vs 10 hrs >20 hrs vs <10 hrs < Any chance of dozing while stopped in traffic Get enough sleep (never/rarely vs. often/always) Neck circumference quartile 2 vs. quartile quartile 3 vs. quartile quartile 4 vs. quartile Note: n= AUSTRALIAN AND NEW ZEALAND JOURNAL OF PUBLIC HEALTH 2005 VOL. 29 NO. 1

4 Sleepiness and motor vehicle accidents sleepiness scores, which combine the likelihood of falling asleep in eight different situations, were not significantly related to accident involvement. This is consistent with a recent populationbased, case-control study of factors predicting injury crashes in the Auckland metropolitan area. 8 A survey of male UK car drivers 4 found Epworth scores to be a marginally significant predictor of self-reported accident involvement (using the same accident question as the present study). However, the relationship between ESS and accident involvement varied among groups in the UK study, being greatest for young professionals driving high annual mileage in company cars, and with a high proportion of driving time spent on motorways. These findings indicate that the relationship between self-reported sleepiness and crash risk is complex, and may be influenced by demographic or exposure factors. This brings into question the usefulness of the Epworth Sleepiness Scale as a clinical tool to identify drivers at risk of motor vehicle crashes. There is robust evidence that people with untreated OSAS are more likely to be involved in motor vehicle accidents. 9,10,12,13 However, in the present study, snoring every night and witnessed apnoeas were not significant independent predictors of reported accident involvement. This contrasts with the survey of 4,621 male UK car drivers, which found that self-report of snoring every night increased accident risk by about 30%. 4 One reason for this difference may be the inclusion of women in the present study. Large neck size is also an independent risk factor for OSAS. 15,26 Paradoxically in the present study, however, being in the smallest (gender-adjusted) quartile for neck size significantly increased the likelihood of reporting crashes, compared with being in the third or fourth quartiles for neck size. A factor that may have contributed to this counter-intuitive finding is that Maori in this sample had significantly larger neck sizes than non-maori, 14 but reported fewer accidents. Table 2: Univariate relationships for reporting at least one accident. Variable Comparison OR 95% CI p Gender male (13.3%) vs. female (11.3%) Age yrs (15.1%) vs yrs (12.1%) < yrs vs yrs (9.7%) < Average weekly driving hours hrs (11.9%) vs. 10 hrs (11.0%) >20 hrs (13.1%) vs. 10 hrs < Ethnicity Maori (11.0%) vs. non-maori (13.2%) NZDep96 decile 2 (14.2%) vs. decile 1 (13.5%) decile 3 (11.1%) vs. decile decile 4 (12.1%) vs. decile decile 5 (12.4%) vs. decile decile 6 (11.3%) vs. decile decile 7 (10.8%) vs. decile decile 8 (15.2%) vs. decile decile 9 (10.7%) vs. decile decile 10 (10.5%) vs. decile Community Services Card yes (11.6%) vs. no (12.5%) Usual sleep in 24 hours (quartiles) <6.5 hrs (12.3%) vs. >8 hrs (11.0%) hrs (13.1%) vs. >8 hrs hrs (11.9%) vs. >8 hrs Get enough sleep never/rarely (14.2%) vs. often/always (11.2%) Wake refreshed never/rarely (12.7%) vs. often/always (11.9%) Excessive sleepiness Epworth sleepiness score >10 (13.4%) vs. ESS=10 (12.0%) Chance of dozing in a car stopped in traffic any chance (16.6%) vs. no chance (11.9%) Snore always (12.3%) vs. never/rarely/often (12.2%) Neck circumference (quartiles by gender) a quartile 2 (13.2%) vs. quartile 1 (13.9%) quartile 3 (10.1%) vs. quartile quartile 4 (11.8%) vs. quartile Observed apnoeas yes (12.6%) vs. no (12.2%) Smoking status regular/occasional (12.6%) vs. ex/non (12.1%) Alcohol consumption non-drinker (13.4%) vs. excess drinker (11.0%) Categorical b moderate drinker (12.4%) vs. excess drinker Notes: (a) Quartile 1, men <39.0 cm, women <33.0 cm; quartile 2, men cm, women cm; quartile 3, men cm, women cm; quartile 4, men 43.0 cm, women 37.0 cm. (b) Categories defined according to the criteria of the Alcohol Advisory Council of New Zealand on upper limits for responsible drinking. 25 Moderate drink alcohol, but not more than the recommended upper limit on an occasion or per week. Excessive drink alcohol more than the recommended upper limit at a typical session ( 5 drinks for women; 7 drinks for men) or per week (>14 drinks for women, >21 drinks for men) VOL. 29 NO. 1 AUSTRALIAN AND NEW ZEALAND JOURNAL OF PUBLIC HEALTH 19

5 Gander et al. Article Study limitations Possible selection bias is inherent in drawing the sample from the electoral roll, since enrolment is voluntary. The estimates of enrolment for the 1998 electoral roll are as follows: yearolds, 90%; year-olds, 93%; and year-olds, 95%. Comparing the number of people of Maori descent on the 1998 electoral roll with the number of people of Maori ethnicity on the 1996 Census suggests that about 95% of Maori were enrolled (a breakdown by age group was not available). 15 Possible response biases include limited English literacy (telephone responding was offered to minimise this), not owning a telephone (thus being unable to respond, or be followed up, by telephone), or having an unlisted telephone number. One of the criteria in the Census-based NZDep96 index is not having a telephone in the household. 19 Across the entire study sample there was a significant trend to lower response rates with increasing socio-economic deprivation. 15 An important limitation of this study is that all data are selfreports. The reliability of self-reported accident involvement is questionable. For example, a recent study of motor vehicle accident rates among 50 OSAS patients found that patients reported only one-third of the accidents documented in official records. 13 There is no way of estimating any potential biases in the present study that may have resulted from under-reporting of accidents. However, the reported annual accident rate per driver in this sample (0.049) is considerably higher than the official statistics for injury accidents (based on police crash reports) for 2000 (0.002 per driver aged years 14 ). This suggests that participants in the present study were reporting many more minor accidents. Nevertheless, the majority of participants (88.3%) reported being accident free in the preceding three years, compared with 82.1% of male British car drivers who were surveyed using the same question. 4 This difference is at least partially attributable to the inclusion in our sample of women (48.4%), who reported lower accident rates. Implications This study suggests that chronic sleep restriction (never/rarely getting enough sleep), and any likelihood of dozing in a car stopped in traffic, may be under-recognised risk factors for motor vehicle accident involvement in New Zealand. The findings are complementary to a recent case-control study in the Auckland metropolitan region, which found that acute sleep loss and sleepiness significantly increased the risk of drivers being involved in an injury crash. 8 Both studies addressed all types of motor vehicle accidents, not only those identified as sleep- or fatiguerelated. These findings reinforce the need for multi-faceted campaigns to reduce sleepy driving. Acknowledgements We gratefully acknowledge the participants who gave their time and support for this work. Financial support was provided by Project Grant 99/185 from the Health Research Council of New Zealand and by a summer studentship from the Wellington Medical Research Foundation to NM. Fisher and Paykel Healthcare sponsored the incentive prize. Special thanks to Gordon Purdie and Noemie Travier for excellent statistical support. References 1. Pomare E, Keefe-Ormsby V, Ormsby C, Pearce N, Reid P, Robson B, et al. Hauora Maori Standards of Health III. Wellington (NZ): Maori Health Te Ropu Rangahau Hauora a Eru Pomare, University of Otago; Pack AI, Pack AM, Rodgman E, Cucchiara A, Dinges DF, Schwab CW. Characteristics of crashes attributed to the driver having fallen asleep. Accid Anal Prev 1995;27: Mitler MM, Carskadon MA, Czeisler CA, Dement WC, Dinges DF, Graeber RC. Catastrophes, sleep, and public policy: Consensus report. Sleep 1988;11(1): Maycock G., Sleepiness and driving: the experience of UK car drivers. J Sleep Res 1996;5: Horne J, La R. Vehicle accidents related to sleep: a review. Occup Environ Med 1999;56: Mondini S, Parazzini F, Mostacci B, Sancisi E, Cirignotta F. Sleepiness and car accidents: epidemiological survey on motorways of Emilia-Romagna and Lombardia (Northern Italy). Sleep 2000;23(Suppl 2): Garbarino S, Nobili L, Beelke M, De Carli F, Ferrillo F. The contributing role of sleepiness in highway vehicle accidents. Sleep 2001;24(2): Connor J, Norton R, Ameratunga S, Robinson E, Civil I, Dunn R, et al. Driver sleepiness and risk of serious injury to car occupants: population based case control study. Br Med J 2002;324: George CFP, Smiley A. Sleep apnea & automobile crashes. Sleep 1999;22(6): Young T, Blustein J, Finn L, Palta M. Sleep-disordered breathing and motor vehicle accidents in a population based sample of employed adults. Sleep 1997;20: Teran-Santos J, Jimenez-Gomez A, Cordero-Guevara J. The association between sleep apnea and the risk of traffic accidents. N Engl J Med 1999;340: George CFP. Reduction in motor vehicle collisions following treatment of sleep apnoea with nasal CPAP. Thorax 2001;56: Findley L, Smith C, Hooper J, Dineen M, Suratt P. Treatment with nasal CPAP decreases automobile accidents in patients with sleep apnea. Sleep 2000;161: Land Transport Safety Authority. Motor Accidents in New Zealand Wellington (NZ): LTSA; Harris RB. Obstructive Sleep Apnoea Syndrome: Symptoms and Risk Factors among Maori and Non-Maori Adults in Aotearoa [Master of Public Health Thesis]. Wellington (NZ): Wellington School of Medicine, University of Otago; Thorpy MJ, editor. International Classification of Sleep Disorders. Revised. Rochester (MN): American Sleep Disorders Association; Johns MW. Sleepiness in different situations measured by the Epworth sleepiness scale. Sleep 1994;17(8): Crampton P, Salmond C, Kirkpatrick R, Scarborough R, Skelly C. Degrees of Deprivation in New Zealand: An Atlas of Socioeconomic Difference. Auckland (NZ): David Bateman; Salmond C, Crampton P, Sutton F. Deprivation and Health. In: Howden- Chapmann P, Tobias M, editors. Social inequalities in health: New Zealand Wellington (NZ): Ministry of Health; p Statistics New Zealand Census of Population and Dwellings: Maori. Wellington (NZ): Government of New Zealand; Tabachnick B, Fidell L. Using Multivariate Statistics. 3rd ed. New York (NY): HarperCollins; Johns MW. Sleep propensity varies with behaviour and the situation in which it is measured: The concept of somnificity. J Sleep Res 2002;11: Akerstedt T, Fredlund P, Gillberg M, Jansson B. A prospective study of fatal occupational accidents relationship to sleeping difficulties and occupational factors. J Sleep Res 2002;11: Roth T, Ancoli-Israel S. Daytime consequences and correlates of insomnia in the United States: Results of the 1991 National Sleep Foundation Survey II. Sleep 1999;22(Suppl 2): Alcohol Advisory Council of New Zealand. Upper Limits for Responsible Drinking: A Guide for the Public. Wellington (NZ): ALAC; Davies R, Ali N, Stradling J. Neck circumference and other clinical features in the diagnosis of the obstructive sleep apnoea syndrome. Thorax 1992;47: AUSTRALIAN AND NEW ZEALAND JOURNAL OF PUBLIC HEALTH 2005 VOL. 29 NO. 1

6 Sleepiness and motor vehicle accidents Appendix A: The questionnaire. 1. What sex are you? Please tick 1 Male 2 Female 2. What is your date of birth?... /... /... (day) (month) (year) 3. Tick as many boxes as you need to show which ethnic group(s) you belong to. a NZ Maori b Samoan c Niuean d Indian e NZ European or Pakeha f Cook Island Maori g Tongan h Chinese i Other European j Tokelauan k Other How many hours sleep do you usually get in 24 hours?... hours 5. How often do you think that you get enough sleep? 0 Never 1 Rarely 2 Often 3 Always 6. How often do you wake feeling refreshed? 0 Never 1 Rarely 2 Often 3 Always 7. How often do you snore? 0 Never 1 Rarely 2 Often 3 Always 8. What is your neck size? Please use the tape measure provided to measure around your neck and write the number of centimetres in the space provided.... cm 9. How likely are you to doze off or fall asleep in the following situations, in contrast to feeling just tired? This refers to your usual way of life in recent times. PLEASE TICK ONE BOX ON EACH LINE would slight moderate high never chance chance chance doze Sitting and reading Watching TV Sitting inactive in a public place (e.g. theatre, meeting) As a passenger in a car for an hour without a break Lying down in the afternoon when circumstances permit Sitting and talking to someone Sitting quietly after a lunch without alcohol In a car, while stopped for a few minutes in traffic PLEASE MAKE SURE YOU HAVE TICKED ONE BOX ON EACH LINE 10. Has anyone ever told you that you stop breathing sometimes during sleep? 1 Yes 2 No 11. During an average week, including the weekend, how many hours would you spend driving a motor vehicle? (not as a passenger) None/ 10 hrs hrs More than non-driver or less 20 hours 12. How many times during the last three years have you been involved in a motor vehicle accident where you were driving? Please write how many times here... times 13. Are you currently having any treatment for any of these conditions? One tick on each line yes no don t know/ can t remember asthma high blood pressure heart trouble diabetes stroke thyroid problem psychological problem sleeping problem SPECIFY Do you describe yourself as a: 1 regular smoker (I smoke one or more cigarettes per day) 2 occasional smoker (I do not smoke every day) 3 ex-smoker (I used to smoke but not any more) 4 non-smoker (I have never smoked regularly) 15. How often do you drink alcohol? Never Less than Once every Once every Daily once a week 3-7 days 2 days 16. On a typical drinking occasion, how many drinks do you have? (One drink equals a glass of beer or a glass of wine or a nip of spirits)? None Less than 2-4 drinks 5-6 drinks More than two drinks 6 drinks 17. Are you eligible for a Community Services Card? 0 Yes 1 No 2 Don t know 18. Please tick this box if you would like to enter the draw for a luxury mystery break. Thank you for your help. Please send us the questionnaire in the replypaid envelope provided or you can phone your response to VOL. 29 NO. 1 AUSTRALIAN AND NEW ZEALAND JOURNAL OF PUBLIC HEALTH 21