In a lecture of that name, Rudolph Steiner said this about contacting the “dead” :

We encounter the Dead at the moment of going to sleep, and again at the moment of waking …

These moments of waking and going to sleep are of the utmost significance for intercourse with the so-called Dead ~ and with other spiritual beings of the higher worlds.

The moment of going to sleep is especially favourable for us to turn to the Dead. Suppose we want to ask the Dead something. We can carry it in our soul, holding it until the moment of going to sleep, for that is the time for bringing our questions to the Dead … On the other hand, the moment of waking is the most favourable for the Dead to communicate with us.