Effects of a Single Dose of Bright Light Treatment on Measures of Affective Information Processing
Condition: Bright Light Treatment; Emotion; Facial Expression Recognition
Study type: Interventional

Summary: 
      This study aims to investigate the effects of a single session of bright light treatment
      (BLT) on emotional information processing in healthy volunteers. We hypothesised that BLT can
      acutely push the processing of emotional information towards a prioritisation of positive
      (relative to negative) input. To test this hypothesis, healthy volunteers were randomly
      allocated to receive either bright light treatment or sham-placebo treatment and study
      participants as well as investigators were blind as to which treatment was used. After
      treatment, all participants underwent testing with the Oxford Emotional Test Battery, an
      established set of psychological tasks that allow to assess how emotional information is
      processed.
    

Detailed description: 
      Background:

      Bright light treatment (BLT) is an efficacious treatment for depressive disorders but the
      causal mechanisms by which it exerts its clinical effects are largely unknown. According to
      the cognitive neuropsychological model of antidepressant treatment action, one way by which
      antidepressant treatments lead to clinical effects is by acutely inducing a relatively
      increased preferential processing of positive (as compared to negative) emotional stimuli.
      Whether BLT has the potential to induce such positive biases is not known to date.

      Aim of study:

      To investigate the influence of single-dose BLT on emotion-related information processing in
      healthy volunteers.

      Methods:

      Using a double-blind, parallel-group design, fifty healthy volunteers (male and female) were
      randomly allocated to a single session (60 minutes) of treatment with either bright light (10
      000 lux) or a credible placebo-sham condition (deactivated negative ion generator). After
      treatment, all participants underwent testing with the Oxford Emotional Test Battery, an
      established battery of behavioural tasks that allow to assess emotional information
      processing in multiple cognitive domains. This battery consists of a facial expression
      recognition task, an emotional categorization task, an emotional dot probe task, an emotional
      recall task and an emotional recognition task. Before and after treatment, subjective state
      was assessed using different questionnaires.

      Hypotheses:

      Our working hypothesis, in line with the cognitive neuropsychological model of antidepressant
      treatment action, is that one-time BLT can induce biases towards positive stimuli in multiple
      cognitive domains and this bias will be present even in the absence of observable changes in
      subjective state.

      Implications of the study:

      This study will show whether a single dose of BLT can influence emotion-related information
      processing in a similar way as previously observed for antidepressant drugs. If this is the
      case, then the clinical effects of BLT could be explained through its acute effects on
      emotional processing. On a broader level, the results of this study will also add to our
      understanding of any potential effects that acute exposure to bright light (e.g. sunlight)
      could have on the healthy human mind.
    

Intervention name(s): Bright light treatment lamp; Sham negative ion generator
Intervention type(s): Device; Device
Intervention description(s): Exposure to bright white light (1 hour, 10 000 lux); Placebo treatment with deactivated negative ion generator (1 hour, audible hum, no ions emitted)
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Triple (Participant, Care Provider, Investigator)
Primary purpose: Basic Science