Here is some info that speaks of the dark period. It is NOT the light period that cannabis reacts to, it is the DARK. Cannabis does not measure the amount of light, it has no relevence, it measures the dark period. There is much information available for those curious about extended light periods during flower. Again, I do not recomend it. Hope this helps to clarify
Many of the biological and behavioural activities of
plants,
animals (including
birds and
amphibians),
insects, and
microorganisms are either adversely affected by
light pollution at night or can only function effectively either during or as the consequence of nightly darkness. Such activities include
foraging,
breeding and
social behavior in higher animals, amphibians, and insects, which are all affected in various ways if light pollution occurs in their environment.
[1] These are not merely photobiological phenomena; light pollution acts by interrupting critical dark-requiring processes.
But perhaps the most important scotobiological phenomena relate to the regular periodic alternation of light and darkness. These include breeding behavior in a range of animals, the control of
flowering and the induction of winter
dormancy in many plants, and the operational control of the human
immune system. In many of these biological processes the critical point is the length of the dark period rather than that of the light. For example, "short-day" and "long-day" plants are, in fact, "long-night" and "short-night" respectively. That is to say, plants do not measure the length of the light period, but of the dark period.
[2] One consequence of artificial light pollution
[3] is that even brief periods of relatively bright light during the night may prevent plants or animals (including humans) from measuring the length of the dark period, and therefore from behaving in a normal or required manner. This is a critical aspect of scotobiology, and one of the major areas in the study of the responses of biological systems to darkness.
In discussing scotobiology, it is important to remember that darkness (the absence of light) is seldom absolute. An important aspect of any scotobiological phenomenon is the level and quality (
wavelength) of light that is below the threshold of detection for that phenomenon and in any specific organism. This important variable in scotobiological studies is not always properly noted or examined. There are substantial levels of natural light pollution at night, of which
moonlight is usually the strongest. For example, plants that rely on night length to program their behaviour have the capacity to ignore full moonlight during an otherwise dark night. If this ability had not evolved, plants would not be able to respond to changing night-length for such behavioural programs as the initiation of flowering and the onset of dormancy. On the other hand, some animal behavioural patterns are strongly responsive to moonlight. It is thus most important in any scotobiological study to determine the threshold level of light that may be required to interfere with or negate the normal pattern of
dark-night activity.