Since de Mairan’s famous initial description of circadian rhythms, through Pittendrigh’s subtle insights and contributions to the field in the 50′, until the development of working models to understand the human circadian, ultradian and infradian rhythms, the development of Chronobiology in the 20th century has been nothing less than astounding, not only because of its importance to physiology alone, but because it is an apt platform for further abstractions trying to understand how the waxing and waning of natural processes include als0 the cycles of life (it has an inherent heuristic value). Just as an example, the genetics of circadian rhythms seem to command cycling rhythms in diferent time scales; in other words, the biological clocks seem to possess self similarity, with a demonstrable common molecular substrate at different time scales. That should be enough to draw the attention of any scientist worth her salt (from any discipline).
In the late 80s, I was lucky enough to learn Chronobiology from Ennio Vivaldi, an expert with a solid scientific foundation (including the ultimate scientific skill: humor). I was very impressed by the work of chronobiologists back then, and I still am. My expectations for that science were high for the following years. I expected greater contributions and especially the advent of new pathophysiological concepts (a clear definition of chronopathies ) linked to some innovative therapeutic interventions (electro-chemical pacemakers?).
Twenty years later, in Baltimore, I got acquainted with a disciple of two Chronobiology pioneers, Wehr and Rosenthal. He seemed to enjoy lecturing about the basics of Chronobiology clinical audiences previously unexposed to the topic. For me, it was utmost interesting to see pretty much the same statements and even the same slides that I saw Vivaldi presenting 20 years before. During one of the lectures, my request, “Can I have your slide from Moore-Ede’s article for my own presentation next week?” must have puzzled him. On the other hand, what puzzled me was that, after 20 years there seemed to be no significant developments beyond what had already been established decades before. Why?
One factor may have been the almost complete isolation between the practicing scientists in that field and the clinicians which could have potentially benefited from that science. While training at the Institute of Neurosurgery in Chile, I remember being approached by a neurology resident who wanted to know how to use light therapy with patients (at the time, a relatively novel approach). The week before, she had interrupted my presentation about the use of Chronobiology in clinics. Visibly annoyed, she had stood up in the middle of my talk to berate me for “bringing up mathematical models” into the discussion (a damning faux pas, I would come to realize).
At this point I’m quite aware that clinicians are not usually willing to bridge the gap between science and care delivery, and I’m fine with that.
For a patient who wants to use a recently purchased light box for treatment of depression, the initial instructions are very simple:
- Understand that there is a sensitive period, about 2 hours after waking up (regardless when the awakening takes place) during which exposure to the light works. Using the lamp after that period is useless and may even be harmful if used in the evening (when any bright light should be avoided).
- Do not stare into the lamp. The retinohypothalamic tract starts from the large peripheral ganglion cells, which respond almost exclusively to the local amount of lighting. All is needed is the peripheral vision to detect the intensity of the ambient light.
- A reasonable starting time of exposure would be 15-30 minutes.
- Work in collaboration with your doctor all the time. There are many factors that may need to be adjusted in order for this or any other therapy to actually work.
The Brain Shop 