title: First cigarette on waking and time of day as predictors of puffing behaviour in UK adult smokers.
abstract: BACKGROUND
  There is known inter- and intra-individual variation in how cigarettes are smoked. The aim of this study was to explore the influence of diurnal factors, particularly the first cigarette of the day, on puffing behaviour in a sample of adult smokers.
  
  
  METHODS
  We recruited 130 adults aged 18–60 years who were smoking one of seven cigarette brands popular in the UK. Puffing behaviour was measured using a portable smoking device (CReSSmicro) through which participants smoked their cigarettes over a 24 h study period. The primary outcome was total smoke volume per cigarette (obtained by summing the puff volumes for each cigarette). Secondary outcome measures were puffing frequency, average puff volume, average puff flow, average puff duration and inter-puff interval.
  
  
  RESULTS
  Total smoke volume was found to be significantly associated with the time the cigarette was smoked (P < 0.001), with cigarettes smoked between 2 and 10 a.m. being smoked less intensively than other cigarettes. After adjusting for time of cigarette, the first cigarette on waking was smoked slightly less intensively than other cigarettes and significantly so if smoked within 5 min of waking (P = 0.004).
  
  
  CONCLUSIONS
  This study suggests that cigarettes smoked during the night and early morning, including the first cigarette of the day, are puffed less intensively. This is a potentially important finding that merits more research given the importance of the first cigarette of the day and diurnal smoking patterns for determining dependence, cessation and relapse.
authors.affiliation: Division of Epidemiology & Public Health, University of Nottingham, UK. Matthew.Grainge@nottingham.ac.uk
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Grainge
authors.forename: Lion
authors.initials: L
authors.lastname: Shahab
authors.forename: David
authors.initials: D
authors.lastname: Hammond
authors.forename: Richard J
authors.initials: RJ
authors.lastname: O'Connor
authors.forename: Ann
authors.initials: A
authors.lastname: McNeill
mesh_terms: D000293:Adolescent; D000328:Adult; D005260:Female; D005544:Forecasting; D006801:Humans; D001239:Inhalation; D008297:Male; D008875:Middle Aged; D012907:Smoking / Q000523:psychology*; D013997:Time Factors; D013996:Time and Motion Studies; D006113:United Kingdom; D055815:Young Adult