We often wake with a dream hangover, even if we don’t recall the dreams that caused it.

Freud said that dreams are full of “day residue”, thoughts and memories left over from waking life. It is no less true that our days are full of dream residue.

Sometimes we become aware of this when we wake up feeling jet-lagged or even as if we have been run over by a truck, even though we seemed to sleep well enough. This is often the effect of what esoteric writers used to call “astral repercussion”. You get out and about in an energy body, in night dreams, and what happens to that astral vehicle may reverberate in your physical system. In extreme cases, like those Dion Fortune made the stuff of the highly illuminating and sometimes cautionary tales in her Secrets of Doctor Taverner, bruises or apparent wounds may be left on the physical body. Those jetlag sensations may be caused by a lot of dream travel;  if you are flying across the world in a dream body, especially if you are crossing large bodies of water (which drain energy from the subtle body) you may have quite literal reasons to feel the way you would feel after a long flight on a plane. Frequent fliers need to learn more about the nature and care and maintenance of energy bodies, which is a major theme in my book Dreamgates.

Our dream activity, remembered or not, often sets the tone for the day. Sometimes we rise with a terrific surge of energy and confidence or a clear sense of direction that was lacking the day before. We may say that we slept well; chances are we also dreamed well.

The “vigilance” theory developed by Finnish dream researcher Antti Revonsuo maintains that in dreams the brain rehearses for patterns of challenge and opportunity that lie ahead, preparing us to move faster and more effectively when certain situations arise, and that this activity is important and useful whether or not we remember our dreams.

Deja vu is one of the most striking examples of dream residue, though many of us fail to understand how it comes about. We meet a person or enter a scene that is absolutely familiar to us; we are sure we have seen this before. Most often this is because we are now catching up, in waking life, with an event that first took place in a dream.

Sometimes dream residue is so outrageous and in our face that we can’t fail to see it. In my book Conscious Dreaming I report an epsode shared with me by a nurse who dreamed she received a visitation from a guide who appeared as half-woman, half-deer. In the morning, she was amazed to find deer scat on the rug in her second-floor apartment. It seemed impossible that it could be there – unless it spilled from the dream.

We might recall Coleridge’s famous questions:

What if you slept? And what if, in your sleep, you dreamed? And what if, in your dream, you went to heaven and there plucked a strange and beautiful flower? And what if, when you awoke, you had the flower in your hand? Ah, what then?

Then we would know that the dream experiences are real, and that what goes on in the dream world doesn’t necessarily stay in the dream world. It happens.