Zohar Lech Lecha #147
When the soul level of Nefesh leaves the body at night, she desires to climb higher in the spiritual levels. If it has impurities attached to her during the day, the soul cannot ascend higher because the kippot on the lower levels block her climb.
The dreams are affected by the level the soul reaches on her way up.
Before going to sleep, it is better to be physically clean and relaxed (Using breathing techniques). Pray (Bedtime Shema), read Zohar, preferably next to a candlelit for a Tzadik. The minimal prayer before sleep is Ana B’Choach, and Shema Israel.
As the soul climbs higher, the dreams have truth and better-supporting messages.
Bedtime Shema prayer-v3