title: Effects of blue light and caffeine on mood.
abstract: BACKGROUND
  Both short wavelength (blue) light and caffeine have been studied for their mood enhancing effects on humans. The ability of blue light to increase alertness, mood and cognitive function via non-image forming neuropathways has been suggested as a non-pharmacological countermeasure for depression across a range of occupational settings.
  
  
  OBJECTIVE
  This experimental study compared blue light and caffeine and aimed to test the effects of blue light/placebo (BLU), white light/240-mg caffeine (CAF), blue light/240-mg caffeine (BCAF) and white light/placebo (PLA), on mood.
  
  
  METHODS
  A randomised, controlled, crossover design study was used, in a convenience population of 20 healthy volunteers. The participants rated their mood on the Swedish Core Affect Scales (SCAS) prior to and after each experimental condition to assess the dimensions of valence and activation.
  
  
  RESULTS
  There was a significant main effect of light (p = 0.009), and the combination of blue light and caffeine had clear positive effects on core effects (ES, ranging from 0.41 to 1.20) and global mood (ES, 0.61 ± 0.53).
  
  
  CONCLUSIONS
  The benefits of the combination of blue light and caffeine should be further investigated across a range of applications due to the observed effects on the dimensions of arousal, valence and pleasant activation.
authors.affiliation: Nationellt Vintersportcentrum, Department of Psychology, Mid Sweden University, 83125, Östersund, Sweden, johan.ekstrom@jll.se.
authors.forename: Johan G
authors.initials: JG
authors.lastname: Ekström
authors.forename: C Martyn
authors.initials: CM
authors.lastname: Beaven
mesh_terms: D000328:Adult; D000339:Affect / Q000187:drug effects* / Q000502:physiology; D001143:Arousal / Q000187:drug effects* / Q000502:physiology; D001288:Attention / Q000187:drug effects / Q000502:physiology; D002110:Caffeine / Q000494:pharmacology*; D000697:Central Nervous System Stimulants / Q000494:pharmacology*; D003071:Cognition / Q000187:drug effects / Q000502:physiology; D018592:Cross-Over Studies; D005260:Female; D006801:Humans; D008027:Light; D008297:Male; D011597:Psychomotor Performance / Q000187:drug effects / Q000502:physiology; D055815:Young Adult
chemical_list: D000697:Central Nervous System Stimulants; D002110:Caffeine