In your Dreams – the science of why, how and when we dream

In your Dreams – the science of why, how and when we dream

Dreams, we all have them, some we remember, some we don’t! There are those who want to analyse every detail of their dreams, seeing them as portents to future events or windows into our souls. Some dismiss dreams as a nothing more than random images as a byproduct of brain activity.

Regardless of what camp of dream analysis you belong to, you may like to know a bit more about the why, how and when of dreams, to fill in the blanks and give a better understanding of what happens when we close our eyes at night.



Are there different types of dreams?

Dreams are a series of images, emotions, senses or events that we experience while we sleep. They are created in the brain, during different brain impulses and can last from a few seconds, to more than half an hour. There are a number of different types of dreams, the classifications vary depending on who you talk to, but in general we experience regular dreams, lucid dreams and nightmares.

The three basic types of dreams are…

  • Regular dreams usually occur when we are in a deep sleep phase, such as the REM (Rapid Eye Movement) stage of sleep.
  • Lucid dreams usually occur when we are in a lighter stage of sleep. We are at least partially aware that we are dreaming and we can consciously change the course of the dream if we so choose.
  • We are all familiar with nightmares and they are not just for children. They are dreams that evoke strong emotions and reactions within us, usually fear, terror, anger or anxiety.

What happens when we dream?

In order to talk about dreaming we must first look at what happens when we sleep and the different stages involved. There are five stages of sleep, stages 1, 2, 3, 4 and the Rapid Eye Movement (REM) stage.

We pass from each stage of sleep sequentially, usually falling into a deeper sleep with each stage. Once we have completed a full cycle (stages 1, 2, 3, 4 and REM) we return to the first stage and the cycle repeats. A full cycle takes between 90 and 110 minutes.

Stage 1

This is a very light stage of sleep, our bodies relax, our muscle activity slows and we experience slow eye movement.

Stage 2

Our eye movements stop, our muscle movements reduce and our brain waves slow down; Our heart rates slow and our body temeratures drop a little. We also experience burst of rapid brain wave activity in this stage, these are called brain spindles. Adults spend about 50% of their sleep time in this stage, this reduces with age.

Stage 3

We enter deep sleep, with some periods of very slow brain waves recorded.

Stage 4

The periods of very slow brain waves extend.

REM Stage

Our eye movement becomes erratic and jerky, our heart rates rise, breathing becomes more rapid and our limbs become temporarily paralysed. We spend about 20-25% of our sleep time in this stage (infants can spend up to 50% of sleep in the REM stage).

The REM stage of the first cycle of sleep is fairly short (about ten minutes) but increases in duration with each cycle (up to an hour in the final cycle).

Stages 1 to 4 of sleep are collectively referred to as the non-REM stages (NREM).

We dream at all stages of sleep but most of our dreams are thought to occur during the REM stage. Studies show that we tend to have different types of dreams at different stages of sleep; In the early stages, we have very short dreams but they are more realistic and relatable. As we move into deeper sleep our dreams tend to become more fragmented. As the night progresses and we experience longer REM states our dreams become more obscure and disjointed.



Why do we dream?

There are a number of theories as to why we dream, but scientists are still not sure. Some say that dreaming is an asinine activity that serves no purpose, but most agree that this is not the case, although they may argue as to the true value of dreams.

Dreaming has no purpose at all

In 1977 psychiatrists J. Allan Hobson and R.W. McCarley theorised that dreams don’t actually mean anything at all. They called their theory the ‘activation-synthesis hypothesis’ and stated that dreams are merely electrical brain impulses that pull random thoughts and imagery from our memories.

Dreaming is an ancient biological defence mechanism

Evolutionary biologists studying dreams and their function have proposed the Threat Simulating Theory (TST) of dreaming.

The threat simulation theory of dreaming states that dream consciousness is essentially an ancient biological defence mechanism, evolutionary selected for its capacity to repeatedly simulate threatening events.

Basically, dreams are seen as a simulation, a way to prepare our bodies and hone our skills for the right response in potentially threatening situations. By experiences threats and events in our mind (like being chased by a wild animal!) we can train our bodies to respond correctly if or when the threat really does appear in real life. We can develop our neuro-cognitive mechanisms.

The TST also suggests that people under threat in their everyday lives will dream more, as a way to exercise and prepare for the dangers they may experience each day. There is some evidence to suggest this is the case.

Scientists in favour of this theory also quote the fact that a convincing 70% of our dreams are made up of such threatening scenarios.

Dreams help us solve problems

It is possible that dreams help us unravel and review all the complexities we have experienced during our waking hours. Without the restrains of our conscious, logical thinking we can view things from a completely different angle. Some people can wake after a night of sleep with their eureka moment, solving a niggling problem, literally while they catch some z’s. Perhaps the most famous case is that of the chemist August Kekule, who supposedly discovered the benzene ring structure after dreaming of atoms linking together in a chain and then twisting, like a snake biting his own tail, into a ring structure.

The famous American writer, John Steinbeck called this the ‘committee of sleep‘…

It is a common experience that a problem difficult at night is resolved in the morning after the committee of sleep has worked on it

How does all this free thinking work? Daytime events and often recorded in fragmented forms in different regions of the brain. The ‘memory’ is held together by interaction of those brain parts with the hippocampus. During certain stages of sleep these connections are lost, but brain activity in each of these regions may continue. This ‘untethered’ brain activity can provide the freedom of thought and creativity that is constrained in the waking hours.

We dream to fulfil our desires

This brings us back to Freud who believed that our dreams were a manifestation of our basic, unconscious desires and urges. He believed that to better understand our own psychological makeup, and issues, we needed to record and analyse the content of our dreams.

We dream to help us process our emotions

Do we dream to help us process emotional events in a safe way? When we sleep the levels of certain stress hormones  in our bodies are reduced, therefore we can reflect on a stressful situation or event, in a safe place, where the stress response has been toned down.

Studies have observed high activity in the amygdala during the REM stage of sleep. This is the area of the brain associated with emotions. This suggests that, while sleeping, our brains access emotional events and memories while the stress neurochemicals (norepinephrine) are suppressed, allowing us to process and resolve any emotions or traumas. We wake feeling better about an event that may have caused us stress the day before.

Dreaming is an important part of our memory storing process

The process of dreaming may help us strengthen, connect and store memories. In order to full consolidate our memories we need to strengthen links between different areas of the brain that have recorded information from the memory, and to integrate the information with previously stored knowledge.

The most basic function of dreaming consists of connecting new material with old material in memory systems; reorganising the memory systems, guided by emotion. (Hartmann, 2011).

Sleep creates an optimal  environment to allow memory links to be repeatedly activated without the interference of external stimuli. This reactivation strengthens the neurological pathways that link the various parts of the memory as well as creating links with older memories and learning.

MRI studies have shown that brain areas associated with short and long term memory consolidation (hippocampus and amygdala) are activated while we dream.

Different types of memories may be consolidated at different stages of sleep; the episodic memories are best processed during NREM stages, while more sensory, procedural and emotional events are likely integrated during REM stages.


How long do dreams last?

Dream length varies, but on average our dreams start off short and get longer as the night progresses. Although some dreams may only last for seconds, our first dream of the night is usually about five minute long, our last dream can be as long as 45 minutes. As most of our dreaming occurring during the REM stage of sleep, as this stage gets longer, so too do our dreams.

Most people have at least two to three dreams per night, with the average being six to seven. We spend about two hours a night dreaming, which can add up to a whopping six years of dreaming in a lifetime!


These theories and insights are fascinating but there is still much to learn. Scientists will continue to research, study and debate the importance of the dreaming process, but, looking at how much of our lives we spend dreaming it is certainly a worthwhile study. 





The Science of Love

I love Bjork’s song about falling in love (“It’s oh so quiet“), the lyrics really describes the chaos involved. We hear talk of being madly in love and sometimes that is exactly the symptoms we express, so this Valentine’s Day I thought I’d take a look at the biological and neurological events behind it all. What is the science of falling in love?

photo credit: Hold me forever via photopin (license)
photo credit: Hold me forever via photopin (license)

Is love ruled by the heart or the brain?

According to a 2010 study entitled “The neuroimaging of love” 12 separate areas of the brain are involved in the process. These areas control the release of a number of chemicals that result in the biological responses of love. Our clear minded focus on the object of our desire, the flushes of our cheeks, the butterflies in our stomach and the fluttering of our heart… the result of hormones (such as testosterone and oestrogen) and neurotransmitters (such as dopamine, serotonin, oxytocin, adrenaline and vasopressin).

Head over heels in love

That first flush of love that literally has you tripping over yourself, how does that work? The wonderful cocktail of biological chemicals that swamp the body as we fall in love literally make us light headed and dizzy. We exhibit a strong focus of thought, an increased tendency to take risks and a stiking increase in energy, stamina and motivation.

Madly in love

The activity in the brain during the early stages of love have been likened to those seen in certain mental illnesses. Sufferers of Obsessive Compulsive Disorder (OCD), for example, exhibit enhanced brain activity in similar areas and experience reduced levels of serotonin (40% less) as do people in the first flush of love. Both tend towards single minded obsession on a particular object, in the case of the love struck, this being the object of their desire.

Love is the drug

It seems love really is THE drug, as the effect on the body during those early, heady days of love are similar to a hit of cocaine! Dopamine, released in larger quantities during the early stages of love, causes that drug like high, including the euphoria, the rapid heart beat and the sweaty palms. Likewise, falling out of love can be just as long and painful as kicking a chemical addiction.

As the biological anthropologist, Dr. Helen Fischer puts it “romantic love is one of the most addictive substances on Earth

Is there such thing as “love at first sight”?

Apparently it can take as little as one fifth of a second to fall in love!

What happens after the first flush?

The honeymoon period is said to last two to three months. The stages of falling in love can be broken down into three phases…

Lust, which is governed by the sex hormones testosterone and oestrogen

Attraction, controlled by the neurotransmitters dopamine, adrenalin and serotonin

Attachment, this is cemented by elevated doses of oxytocin and vasopressin

Once the heady stages of love start to subside the major “long term bonding” comes under the control of oxytocin and vasopressin. The higher levels of oxytocin (the cuddle hormone) are understandable, it is linked to the bonding process between mother and baby and helps with the let down of milk during breastfeeding. In general, the more physical and demonstrative the loving couple are, the more oxytocin is produced, strengthening the bond.

The role of vasopressin is a little more surprising. It is primarily linked with water retention and kidney activity and it was a study on prairie voles, of all things, that lead to the link between vasopressin and bonding of couples. It would seem that vasopressin is present in high levels in prairie mates, when it is clinically suppressed in the male prairie vole his interest in the female wanes and he stops protecting her from the advances of rival mates.

Keeping love alive 

Couples who are more physical and affectionate with each other are more likely to have a stronger, long term relationship. Staying positive about your partner also seems to play a vital role. Other Studies show that couples who actively engage in exciting and novel activities together have a better chance of staying together. So for your next “date night” check out your nearest sky diving or abseiling club!

Elderly couple in love (2)

Back to Bjork

Despite all this science to explain it, I still think that Bjork nails it with her description of falling in love, so I leave you with this… and whether you are in the quiet or the chaos of love, I hope you have a good Valentine’s Day.