If you define happiness as being in the moment, then the corollary sounds logical.
To say that the wandering mind causes depression is to tell every parent to be concerned when their child is introspective. Most intellectual behaviour may be like that.
Dreaming does not result in depression. However, addiction to external stimuli do create patterns in modes of thinking and when the stimuli is removed bad feelings logically follow.
Creativity often involves introspection and the mind wandering. Creativity is being in the moment of thought.
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