Mental health is the capacity to review independently one’s mental state as it is perceived by others.
One may have the capacity to review independently one’s mental state as it is perceived by others, but one may choose not to use it.
Blushing signals that one cares about how one is perceived by others.

Theory of mind, mentalization, and empathy are indices of a subject’s imagination that do not require the subject to imagine the subject as object.

In game theory, one reviews independently one’s choices as they are perceived by others.

Regression is when an adult chooses to behave like an adolescent or a child. Regression may be a response to feeling condescended or patronised, or it may be a move in sexual negotiations. The regressed person has the capacity to recognise, discuss and stop the regressed behaviour.
Habitats and workplaces can be scaled in their tolerance of regression, given the spectrum of their responses. The regressed wish to be the centre of attention may produce maladaptive stimuli.
Divorce sets limits on the tolerance of regression.
When social principles are used as excuses for adult irresponsibility, immediate zero tolerance of regression should follow.
In a busy hospital casualty department, signs that distinguish regression from depression and anxiety are occasional sidelong glances to see what effect is being had, the absence of lachrymosity, a voice that does not quaver, and a coarse tremor of the hands.
Pseudo-conversation is an example of regression.
Holidays are times of regression.

Mental health fluctuates over time within individuals. The timescale of the fluctuations may be ultradian, circadian, hebdomadal, lunar or seasonal.
How long does an episode of lack of mental health last; seconds, minutes, hours, days, weeks, months, years?
Emotionality is a major cause of fluctuations in mental health.

Mental health is scaled downwards from mental illness, instead of being scaled upwards from a necessary and sufficient condition for mental health, which contributes to the high threshold for lack of mental health.
In England, the threshold for lack of mental health is unlikely to change because of the reluctance to ask the Churchillian question: “Why is this person behaving in this way, in this place, at this time?”, irrespective of that person’s social status and of the organisations to which that person belongs. Norman Bettison, who defamed the dead, was made Sir Norman Bettison.
Definitions of mental health without discussion of necessary and sufficient conditions for mental health lack scholarship.
Membership of organisations may buffer fluctuations in mental health, but the organisations become vulnerable, as shown recently by Yorkshire Cricket Club and the Marylebone Cricket Club.
Organisations become vulnerable when members talk too much to each other and not enough to those in other organisations. Jargon and neologisms are warning signs, for example, the ‘bazball’ of english cricket. The famous experiment by Libet (1983) captured the lack of imagination of a great many people, in spite of the sophomoric error of presuming that because a motor behaviour followed electrical activity, it was causally related to that electrical activity. Within organisations, modules can become information silos.

Variation within individuals is a source of error in supposedly scientific studies, and in models of human behaviour. “Evidence for Joint Encoding of Motion and Disparity in Human Visual Perception” was published in the Journal of Neurophysiology in 2008, 100(6) 3117-3133, and gave no information about the human participants, which was inadvertent social information about the researchers, the reviewers and the editor: Google counted 25 citations in 18 years.

The lack of a description of mental health has limited sexual selection, because young people have not known what they should be looking for.

The social media are monitors for lack of mental heath. Perhaps relatedly, there has been an increase in explanatory references to mental health, but these lack consensus. The decline in the marriage rate is consistent with perceived uncertainty about the effects of marriage on one’s mental health.