Dreaming LifeDreaming Life

The costly signaling theory of dreams, a theory based on evolutionary biology, was developed by neuroscientist Patrick McNamara and psychologist Reka Szent-Imrey in 2007. The costly signaling theory of dreams says that dreaming is harmful to us. When we show others that we can handle the dangerous effects of dreaming, we show them that we are strong individuals.

Costly Signaling

Sometimes an animal will have a trait that seems to put it at a disadvantage. In fact, this trait ultimately benefits the animal by showing others that the animal is healthy enough to cope with this trait. Evolutionary biologists call this "costly signaling."

An example of this happens in young, healthy gazelles, who sometimes exhibit a type of behavior known as "stotting". A gazelle will jump up and down in front of a healthy leopard instead of immediately running away. At first glance, it seems that the gazelle is putting itself in danger unnecessarily. However, the stotting makes the leopard think that the gazelle must be extremely healthy and fit to have the courage to get so close. The leopard assumes that the gazelle is going to be very difficult to catch and so moves on to other gazelles who do not display this behavior.

Costly signaling is often associated with communication between animals when both animals are capable of deceiving each other but, at the same time, are relying on each other to be honest. If they continually deceive each other, they will evolve to just ignore each other. Therefore, they need to use symbols that are difficult to fake.

This situation can occur during mating, when a female chooses a male with whom to mate. In order for the female to be able to trust that the male she chooses is a good genetic "catch," the male must use a symbol that disadvantages him and is therefore hard to fake. For example, a peacock's elaborate tail makes it difficult for the peacock to escape predators, while it is difficult for a male reindeer to grow large antlers because they are easily infested by parasites. Therefore, when a peahen spots a peacock with a very ornate tail, or a female reindeer sees a male reindeer with very large antlers, she can be assured that the male is healthy and possesses genes that are of the highest quality.

Dreaming is Costly

McNamara and Szent-Imrey say that dreaming is disadvantageous to the dreamer. They point out that dreams are often unpleasant, a fact that was noted by Antti Revonsuo when he developed his theory that we evolved the ability to dream in order to prepare ourselves for threatening situations. In dreams, the dreamer often suffers from a handicap - the dreamer is naked, is being chased, is being attacked, and so on. Research performed in 2003 says 80 percent of all dreams include negative emotions.

After the dreamer wakes up, the unpleasant content of a dream will continue to influence his or her mental state. This causes the dreamer to be emotionally disadvantaged in waking life. A 2006 study found a consistent relationship between psychological well-being and the content of dreams. Nightmares are associated with post traumatic stress disorder and thoughts of suicide in people who are depressed.

REM Sleep is Costly

High levels of REM sleep, the type of sleep in which vivid dreams are most likely to occur, are associated with depression and an increased risk of mortality. During REM sleep, the heart rate fluctuates significantly and breathing becomes very irregular. The breathing patterns associated with REM sleep can be life threatening for some people.

The paralysis associated with REM sleep is also a disadvantage, as it makes the sleeper more vulnerable to predators.

While McNamara and Szent-Imrey acknowledge, as Mark Solms discerned from his research, that dreams and REM sleep are not the same thing, they say that REM physiology accounts for a large portion of dream content. Changes in brain activity during REM sleep are reflected in changes in the plots, imagery and emotional content of dreams. Recent studies have shown that the part of the brain known as the amygdala is very active during the REM state. The amygdala is associated with feelings of fear and other negative emotions.

The Benefits of Costly Dreaming

Dreams can cause you to experience negative emotions throughout the day. However, displaying negative emotions can actually give you a social advantage, because it will make others think you have survived a difficult situation, which will therefore cause them to believe that you are a strong person. In addition, a display of negative emotions can cause others to be sympathetic towards you.

McNamara and Szent-Imrey say that if their theory is true, the people who are most in need of forming ties with others will be the most likely to remember their dreams. They found that people who are single but are actively seeking a relationship are much more likely to remember their dreams than people who are in secure relationships and people who are not concerned about being in a relationship.