While the taus of BFRs are probably the most accurate estimate of the genetically programmed intrinsic tau (which might be of use in studying clock genes in humans95-97), we also suggested that the DLMO ZT in sighted people might be a useful way to estimate at least the functional tau in people entrained to the light/dark cycle. Melatonin treatment can be initiated at any time in BFRs What would have happened Inhibitors,research,lifescience,medical if melatonin treatment were initiated in BFRs on the “wrong” zone of the melatonin PRC? In animal studies, it does not matter when the entraining stimulus is given: eventually, the pacemaker is stably entrained

at a steady-state phase position, once the entraining stimulus comes into contact with the entrainment point of the PRC.98 However, in a study published a few years ago, the University of Surrey research group found that they were able to entrain only about half of their Inhibitors,research,lifescience,medical group of seven BRFs to a 5-mg dose of melatonin.99 They noted that entrainment was successful only when melatonin treatment was started on the advance zone of the PRC, but not when treatment was started on the

delay zone, even if daily melatonin doses were continued through a complete circadian beat cycle, so that eventually melatonin stimulated all of the advance zone. They further noted that this finding contradicted those of animal studies, in which starting a zeitgeber on the delay zone did not affect its capability to Inhibitors,research,lifescience,medical eventually cause entrainment (it just took longer before the entrainment point was reached as the pacemaker, and the PRC, drifted into phase). If the Surrey group is correct, this would mean that all BFRs should have frequent. MO assessments to determine Inhibitors,research,lifescience,medical on

what day melatonin treatment should be initiated. Fortunately, this docs not appear to be true. We found in seven out of seven BFRs that when low-dose melatonin is initiated on the delay zone, entrainment eventually occurs when melatonin is given at the entrainment point in the advance zone.100 The following case (Figure 6) using 0.05 mg is an example; in the other cases, a dose of 0.5 mg was used. Recently, the Surrey group found Inhibitors,research,lifescience,medical that some BFRs entrained when Mephenoxalone 0.5 mg was initiated on the delay zone; however, they continue to recommend initiating melatonin treatment on the advance zone. Figure 6. Blue circles represent an assessment of circadian phase as determined by the time that endogenous salivary melatonin concentrations continuously rose above the 0.7 pg/mL threshold. Tasocitinib Vertical lines represent the timing and duration (days) of exogenous melatonin … Very low doses of melatonin are effective in entraining BFRs In this case (Figure 6), a very low dose (0.05 mg) of melatonin was initiated in a BFR with a tau of 24.35 h on the delay zone (CT 4.95). Initially, a clear increase in tau occurred, consistent with a greater daily phase delay. Within a few days, melatonin was stimulating the advance zone and once the entrainment point was reached, the pacemaker locked on.