Correction: everyone you
want's invited.
Mine are usually fairly disappointing, though. In one I got out of bed, looked out of the window, walked downstairs, went into the garden and promptly woke up - in technicolour. Woo-hoo. And I've tried flying but it never lasts too long.
There are some useful tips at the
Lucidity Institute, which do seem to improve the frequency and sustainability of the things.