In general, this disclosure describes techniques for initiating a communication session when a user indicates she or he is available to participate in the communication session. The protected luminophore provides increased stability and improved signal-to-background ratios relative to the corresponding unmodified coelenterazine. Next, the therapy delivery device is activated to deliver a therapy signal to the ANS nerve target in an amount and for a time sufficient to effect a change in sympathetic andor parasympathetic activity in the mammal and thereby treat the circadian rhythm disorder. A second base for supporting the body of the optical fiber is secured to the optical signal receiving region of the first base.