Study objective: To investigate the association between markers of socioeconomic position (years of full time education, access to a car or van, and occupational social class) and mid-range sleep quantity (6.5 to 8.5 hours). Data source: Office of National Statistics Omnibus Survey, May 1999. Participants: 3000 households were randomly selected from the UK postcode address file and one person aged over 16 years from each household was randomly selected and invited to take part in the survey. All respondents aged 25 and over (n = 1473) were included in the analyses where appropriate data were available. Main results: Total sleep quantity was greater in more deprived women as measured by years in full time education. There was no linear association between total sleep quantity and any of the markers of socioeconomic position in men. Mid-range sleep quantity was more common in more educated women. Similar, non-significant, trends were seen in men. Conclusion: There is little evidence that more socioeconomically deprived people obtain less sleep than more advantaged ones-indeed, the reverse may be true-but some evidence that more advantaged women are more likely to report mid-range sleep. Any hypothesis implicating sleep in socioeconomic inequalities in health should take into account mid-range, rather than total, sleep quantity. Further work should focus both on mid-range, or ''healthy'' sleep, quantity as well as sleep quality.T here is evidence that sleep deprivation is associated with impaired glucose tolerance and hypertension.1 2 As these disease markers, as well as numerous disease outcomes, vary according to socioeconomic position (SEP), 3 it has been suggested that variations in sleep quantity may mediate the relation between SEP and health.4 Theoretical reasons for this include known socioeconomic variations in stress, 5 housing quality, 6 and overcrowding. However, the association between sleep quantity and both morbidity and mortality seems to be U shaped with lowest risk at around six to eight hours of sleep per night. [8][9][10][11] Published data on SEP and sleep quantity are sparse but have failed, to date, to report a linear association. [12][13][14] In fact, there is some evidence of an inverse linear association between SEP and sleep.14 One recent analysis of US data investigated socioeconomic variations in short (,6.5 hours), mid-range (6.5-8.5 hours), and long (.8.5 hours) sleep finding that lower educational attainment was associated with increased risk of being a short or long sleeper.
15To provide further information on the association between SEP and sleep quantity, and the first such data from the UK, data from the UK Office for National Statistics' (ONS) Omnibus Survey were analysed.
METHODSThe ONS Omnibus Survey is a regular, multi-purpose, survey.16 17 Each month 3000 private households in the UK are randomly selected using the postcode address file and one randomly selected person aged over 16 from each household is invited to take part in the survey. In May 1999, respondents were asked...