Related Experiment Video
Updated: May 2, 2026

Experimental Protocol for Examining Behavioral Response Profiles in Larval Fish: Application to the Neuro-stimulant Caffeine
Published on: July 24, 2018
Effects of blue light and caffeine on mood
Johan G Ekström1, C Martyn Beaven
1Nationellt Vintersportcentrum, Department of Psychology, Mid Sweden University, 83125, Östersund, Sweden, johan.ekstrom@jll.se.
Rationale:
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.
Objectives:
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.
Related Concept Videos
Insufficient Sleep and Sleep Deprivation
Sleep deprivation is a more severe form of sleep loss...
The Influence of Affect on Cognition
Factors Affecting Perception
An illustrative example of a perceptual set is the scenario where an airline pilot told...
The Influence of Cognition on Affect
The Placebo Effect
Photoreceptors and Visual Pathways

