I too have no knowledge about the clinical effects of Transcendental Meditation on melatonin and the latter's effects on sleep patterns. But I would imagine that as the bodily functions begin to normalize through daily transcending, sleep patterns would be part of such a normalization process.
Further, for humans who are not really nocturnal beings, I would imagine that the more natural bodily response would indeed be to shift into sleep mode once darkness has come, and to feel awake at first light in the morning. So ... my own self-informed logic without scientific backup would suggest that after learning TM or NSR one would in time feel like going to bed earlier than before becoming a regular meditator. I understand too, however, that age can also influence sleep patterns, as can a host of other factors.
I have found lately that I am going to bed earlier, yet I am waking up later than, say, six months ago. Perhaps my system is taking more rest after having been pushed for so long with publishers' deadlines.
Regarding the social and family implications, I think sleep patters are only one area in which a meditator's life changes over time. I have always thought that it is advantageous for both partners to learn the meditation technique, and hopefully also stay regular with it. As consciousness unfolds, it it good if both partners can experience changes. If one partner grows faster than the other, some compromises may become necessary in order for good harmony to prevail.
Anyway, these are just my personal opinions.
