In an interesting study of adolescent sleep patterns, Crowley and Carskadon, of Rush University Medical Center in Chicago, examined melatonin rhythms in a group of adolescents who were assigned to sleep later and sleep more than their typical weekday pattern[1]. Mimicking the common pattern of many adolescents who are relatively sleep deprived during the school week but who compensate by lengthening and delaying their sleep schedule during the weekend, these investigators measured the timing of melatonin secretion (dim light melatonin onset) in subjects who had this typical delayed, extended pattern, in subjects who had an afternoon nap condition, and in subjects who received one hour of bright light on awakening.  Consistent with their expectations, they found that melatonin rhythms were delayed in all conditions and that bright light therapy was ineffective in correcting this delay.

This research confirms that the delayed, extended weekend sleep hours of adolescents are associated with actual delays in the timing of melatonin secretion.  Delays of this kind are frequently associated with depression[2].  Whether these weekend phase shifts increase the risk for depression or mood instability is not known.  Publications of this kind nonetheless sensitize us to the biological, psychiatric, and public health implications of how standard and uniform school schedules interact with the constitutional timing preferences (chronotypes) of late-sleeping adolescents.

 

1.            Crowley, S.J., et al., Modifications to weekend recovery sleep delay circadian phase in older adolescents. Chronobiology International, 2010. 27(7): p. 1469-92.

2.            Lewy, A.J. and A.J. Lewy, Depressive disorders may more commonly be related to circadian phase delays rather than advances: time will tell. Sleep Medicine, 2010. 11(2): p. 117-8.

 

Research on the use of bright light therapy in the treatment of depression is almost three decades old.  Starting with the initial study of Rosenthal and colleagues in 1984, research on this chronotherapeutic modality has progressed through several phases.  Following the initial reports of efficacy, which were tied to seasonal affective disorders, the next ten to fifteen years were spent clarifying the optimal treatment parameters and mechanism of action of this new strategy.  This phase resulted in the astonishing clarification of the circadian origins of Fall/Winter depression.  This is an under-appreciated finding.  Our field is long on investigation and hypothesis-generation and quite short on definitive analyses.  To have a true biomarker of a mood disorder (phase delay as measured by dim light melatonin onset) that correlates with illness and remission states is unprecedented.

The new phase of research in this field is now testing the boundaries of application for this novel treatment.  The first expansion was into non-seasonal depressions.  There is now strong support for bright light therapy in this population.  Early investigation is underway in other diagnostic groups including bipolar depression, ante-partum and postpartum depressions, premenstrual dysphoric disorder and bulimia nervosa.

The recent study in the Archives of General Psychiatry by Ritsaert Lieverse, MD and his colleagues in the Netherlands continues this boundary-testing by examining the use of light therapy in a new patient group:  the elderly who suffer from depression [1].  The appropriateness of this study is obvious:  not only is this a group who experience high rates of depression, they are also a group in need of safe and effective antidepressant interventions.  Because of the higher rates of medical comorbidity and medication use in this group, antidepressant pharmacotherapy poses increased risk and the potential for increased side-effects.  The need for alternatives is clear.

To this end, Lieverse and colleagues used a well-designed, placebo-controlled, randomized, double-blind study to test the effectiveness of bright light therapy in adults over sixty years old with major depression.  Guess what?  It works.  The percentage of patients with clinically meaningful response to active treatment was significantly higher than those receiving the dim red light placebo.  This was true after three weeks of treatment.  Interestingly, this response rate continued to rise even after the treatment was stopped.  Does light therapy induce a remission process that continues and gains steam even after its discontinuation?

So, let’s take a minute to review the status and conclusions of this field of research.

1.         Bright light therapy has passed the initial and replication phase of research credibility.

2.         Its dosing parameters and timing have been clarified and agreed upon.

3.         As a rule, it acts more quickly than pharmacotherapy.

4.         It is effective in both seasonal and non-seasonal forms of depression.

5.         It has fewer systemic side-effects than pharmacotherapy.

6.         It is cost-effective.

To be sure, unanswered questions remain:  how does bright light therapy work in more severe, melancholic conditions?  What is its role and how should it be used in bipolar disorder?  Are the presence of anxiety symptoms a relative contraindication to the use of bright light therapy, as is true for antidepressant pharmacotherapy in bipolar depression?  How can light and antidepressants be combined for optimal benefit?

While these questions remain, they shouldn’t obscure a more basic recognition:  bright light therapy is no longer a novel finding.  It’s an established veteran with an expanding sphere of influence.

1.         Lieverse, R., et al., Bright Light Treatment in Elderly Patients With Nonseasonal Major Depressive Disorder: A Randomized Placebo-Controlled Trial, in Archives General Psychiatry. 2010. p. 61-70.