Light treatment for seasonal affective disorder: theoretical considerations and clinical implications

Good, better, best? The effects of polarization on photobiomodulation therapy

Photobiomodulation therapy (PBMT) is a widely adopted form of phototherapy used to treat many chronic conditions that effect the population at large. The exact physiological mechanisms of PBMT remain unsolved; however, the prevailing theory centres on changes in mitochondrial function. There are many irradiation parameters to consider when investigating PBMT, one of which is the state of polarization. There is some evidence to show that polarization of red and near-infrared light may promote different and/or increased biological activity when compared to otherwise identical non-polarized light. These enhanced cellular effects may also be present when the polarized light is applied linear to the tissue direction. Herein, we synthesize the current experimental and clinical evidence pertaining to polarized photobiomodulation therapy; ultimately, to better inform future research into this area of phototherapy.

An Integrative Approach to Depression: Part 2—Assessment and Treatment

This article is the second of a two-part series presenting an integrative model for understanding and treating depression. In this part, the integrative model provides the basis for comprehensive assessment and treatment, guiding the application of a wide variety of treatments. Evidence-based complementary and conventional treatment modalities for depression are also reviewed.

A longitudinal investigation of seasonal variation in mood

A prospective panel study was conducted to measure seasonality of mood in a random community sample in Melbourne, Australia (N = 245). Based on research into the structure of human mood, it was predicted that a lowering of mood in winter relative to summer would be observed in positive affect (PA) and behavioral engagement (BE), but not negative affect (NA). These variables were measured across summer and winter for 3 years. Consistent with the majority of research in the Northern Hemisphere, analyses on the entire sample found evidence of a small prospective season effect on the BE scale (explaining 2.1% of variance in BE scores). Also, as expected, no season effect was seen on the NA scale. In the entire sample, the season effect was not significant for PA, but joint factor analysis of the BE, PA, and NA scales confirmed that the season effect seen in the BE scale was largely due to items that were pure measures of PA. Winter pattern seasonality was both reliable across measures and significantly more marked among the subgroup of respondents who self-identified winter pattern of mood on the Seasonal Pattern Assessment Questionnaire.

Seasonal affective disorder in Australia: is photoperiod critical?

OBJECTIVES

Seasonal affective disorder (SAD) is a variant of recurrent depression in which episodes are linked to a particular season, typically winter. SAD is understood as the extreme end of a continuum of seasonality in the general population. Photoperiod (the timing and duration of daylight) has been assumed to be aetiologically critical. The present research used a survey design to investigate the assumed centrality of photoperiod for SAD/seasonality in Australia. Two hypotheses were tested: that self-reported seasonality does not increase further from the equator and that seasonality does not stand alone from non-seasonal neurotic complaints.

METHOD

The sampling frame used was adult females on the Australian Twin Registry roll. A sample of 526 women residing across the latitudes of Australia responded to a survey based around the Seasonal Pattern Assessment Questionnaire (SPAQ). The SPAQ asks respondents to retrospectively report on season-related changes in mood and behaviour. The survey also contained three questionnaire measures of neurotic symptoms of anxiety and depression: the General Health Questionnaire (GHQ), the Community Epidemiological Survey for Depression (CES-D) and the State-Trait Anxiety Inventory-Trait (STAI-T).

RESULTS

Self-reported seasonality did not correlated with latitude (r = 0.01, NS). On the other hand, a substantial relationship was found between seasonality and each of the measures of non-seasonal complaints: GHQ (r = 0.35, p < 0.001); CES-D (r = 0.35, p < 0.001); and STAI-T (r = 0.30, p < 0.001).

CONCLUSIONS

Within the limitations of a design based on retrospective self-report, the findings of the present study suggest that the diathesis for SAD/seasonality may not be photoperiod-specific. At least in Australia, there is provisional support for the proposal that human seasonality may have a broader psychological component. The findings are discussed in terms of established research into normal mood, trait personality and non-seasonal depression.