Similarly, a previous study comparing the MCTQ-derived midpoint of sleep in free days and DLMO
found that the differences between them could be in a 4-hour range .
found that millisecond patterns of 2000-3000 lux photic stimulation that triggered phase shifts of DLMO did not influence the overall salivary concentration of melatonin, unlike continuous light exposure at the same intensity, which led to 50% reductions in hormone secretion [156, 158].
Spence et al., "Dim light melatonin onset (DLMO): a tool for the analysis of circadian phase in human sleep and chronobiological disorders," Progress in Neuro-Psychopharmacology and Biological Psychiatry, vol.
The model of melatonin secretion provides a set of parameters directly characterizing melatonin cycle, such as minimum melatonin concentration, melatonin release amplitude, phase shift of melatonin release, estimated sleep duration, and DLMO onsets and offsets, which could be of potential clinical usefulness as factors facilitating classification of sleep disturbances.
Although the MLT(t) function shape disturbance is a common feature for the studied groups, the AG model characteristics differ from the CG and EG ones with respect to phase shift of melatonin release (b3) and estimated sleep duration ([b.sub.4]), but the DLMO offset parameters (because they are expressed by the sum of [b.sub.3] and [b.sub.4]) are the strongest differentiating parameters.
The DLMO parameters obtained for the AG group differ than those for the healthy children.
Consequently, for the 50% threshold, the DLMO onset equals
whereas the DLMO offset at the same threshold level (50%) is
In case of the DLMO values at the 25% threshold level, the trigonometric parts do not reduce to simple expressions as for the 50% threshold ((3) and (4)).
whereas the DLMO offset of melatonin synthesis at the 25% threshold level is defined as
The calculated parameters [b.sub.1] (minimum melatonin concentration), [b.sub.2] (melatonin release amplitude), [b.sub.3] (phase shift of melatonin release), [b.sub.4] (full width at half maximum (FWHM) of melatonin secretion model), [b.sub.max] (maximum melatonin concentration), [DLMOon.sub.50] (DLMO onset at the 50% relative threshold), [DLMOoff.sub.50] (DLMO offset at the 50% relative threshold), [DLMOon.sub.25] (DLMO onset at the 25% relative threshold), and [DLMOoff.sub.25] (DLMO offset at the 25% relative threshold) were subjected to statistical analysis, and the results were interpreted in view of the characteristics of melatonin secretion.
As seen from Table 1, the TSC DLMOon and DLMOoff values obtained for patient 1 are shifted in the later hours as compared to the corresponding DLMO values for the other TSC cases.