Thanks for that article Zoth!

As I understood it - also only flying over - they did test the long term meditators in sleep for methodological reasons.
They wanted to see if there is something different, even while they do not meditate.
The question, whether there were LDers among them - or even dream-meditators - does not show up, though..

An important question raised by these studies is whether
enhanced EEG activity is state dependent (e.g.– occurring only
during meditation and immediately after it), or trait dependent
(e.g. – occurring outside of formal meditation practice) [5].

The latter would suggests that long-term meditation training causes
lasting neuro-plastic changes in cortico-thalamic circuits, which
should be detected in the spontaneous brain activity [9].

This question is difficult to address because meditation training occurs
at multiple time-scales. For example it can happen intensively, as
during meditation retreats, or less intensively but across a longer
period, as during daily practice. Training also occurs, in different
contexts, either during formal practice, or when the practitioner
intentionally cultivates meditative qualities within her/his daily
activities. Another critical methodological issue is that resting state
in meditation experts may be an elusive concept. Indeed, it is
possible that during wakefulness a meditator may spontaneously
enter a meditative state while "at rest" as a consequence of his/her
level of training.

However, during sleep brain activity is directed
by neither conscious effort nor attention, but rather reflects the
intrinsic function of cortico-cortical and cortico-thalamic circuits
Thus, the examination of sleep EEG is an effective means to
identify individual trait differences in the brain unconfounded by
the effect of meditation on waking mentation. [...