What Is the Activation-Synthesis Model of Dreaming?

Activation-synthesis suggest brain activity leads to dreaming
Shuji Kobayashi / Getty Images

The activation-synthesis theory is a neurobiological explanation of why we dream. The question of why people dream has perplexed philosophers and scientists for thousands of years, but it is only fairly recently in history that researchers have been able to take a closer look at exactly what happens in the body and brain during dreaming. Harvard psychiatrists J. Allan Hobson and Robert McCarley first proposed their theory in 1977, suggesting that dreaming results from the brain's attempt to make sense of neural activity that takes place during sleep.

A Closer Look at the Activation-Synthesis Theory

The activation-synthesis model suggests that dreams are caused by the physiological processes of the brain. While people used to believe that sleeping and dreaming was a passive process, researchers now know that the brain is anything but quiet during sleep. A wide variety of neural activity takes place as we slumber. Part of this is because sleep helps the brain perform a number of activities including cleaning up the brain and consolidating memories from the previous day.

How does brain activity during sleep lead to dreaming? According to Hobson and other researchers, circuits in the brain stem are activated during REM sleep. Once these circuits are activated, areas of the limbic system involved in emotions, sensations, and memories, including the amygdala and hippocampus, become active. The brain synthesizes and interprets this internal activity and attempts create meaning from these signals, which results in dreaming.

Hobson also suggested that there are five key characteristics of dreams, which are illogical content, intense emotions, acceptance of strange content, strange sensory experiences, and difficulty remembering dream content.

Reaction to the Theory

The initial publication of their research stirred up considerable controversy, particularly among Freudian analysts.

Since many dream researchers and therapists invest considerable time and effort trying to understand the underlying meaning of dreams, the suggestion that dreams were simply the brain's way of making sense of activity during sleep did not sit well with many.

Does It Mean That Dreams Are Meaningless?

While the activation-synthesis model of dreaming relies on physiological processes to explain dreaming, it does not imply that dreams are meaningless. According to Hobson, "Dreaming may be our most creative conscious state, one in which the chaotic, spontaneous recombination of cognitive elements produces novel configurations of information: new ideas. While many or even most of these ideas may be nonsensical, if even a few of its fanciful products are truly useful, our dream time will not have been wasted" (1999).

More Psychology Definitions: The Psychology Dictionary


Hobson, J.A. & McCarley, R.W. The brain as a dream-state generator: An activation-synthesis hypothesis of the dream process. AMERICAN JOURNAL OF PSYCHIATRY, 134:1335-1348, 1977.

Hobson, J. Allan. (1995) Sleep. New York: Scientific American Library.

Hobson, J. Allan. (1999). Consciousness. New York: Scientific American Library.

Continue Reading