Professor Jim Horne

Sleep Neuroscientist − BSc, MSc, PhD, DSc, FSB, FBPsS, CPsych, CBiol





Loughborough Sleep Research Centre

Awake Ltd

Journal of Sleep Research

Jim Horne at

Jim Horne at Google Scholar




The Stuff That Dreams are Made of

Even though the sleeper has little knowledge of what is happening during sleep, the slumbering brain doesn’t just switch off like the bedside light, but is preoccupied with the events and thoughts of recent wakefulness. For much of sleep (‘non-dreaming’ sleep) these ruminations, whether they be happy, sad, or whatever, are fairly rational, slow moving, unimaginative and not particularly visual. In contrast, and to liven matters up, every ninety minutes during sleep the curtain rises on the cinema of the mind and dreaming sleep begins, lasting for twenty minutes or so at a time. This bizarre, technicolour pastiche of unpredictable, fast moving and usually fascinating scenes is largely based on previous waking events, distorted in irrational ways. By waking up out of a dream and immediately going over it, the dreamer can usually make some sense of it all. Dreams are idiosyncratic, and because only we know about the previous day’s events and thoughts, we are the best interpreters of our dreams. As the symbols in dreams mean different things to each of us, dream “dictionaries” and books on dream analysis purporting to explain the symbolism, are the fantasies of their authors, being greater works of fiction than are the dreams themselves.


Dreaming sleep is also known as ‘rapid eye movement (REM) sleep’, because the eyes move in bursts of activity, similar to that in wakefulness, when we normally look around. This is not scanning the dream imagery, as the eye movements remain when the part of the brain responsible for dreaming is damaged or destroyed. During dreaming sleep our bodies and limbs have the potential to enact the dream and move about quite violently, which would be hazardous. To prevent this happening the brain paralyses the body, preventing all movement other than some twitching of the hands and feet and, of course, the eye movements. Breathing and other vital functions continue almost as normal. Sometimes, when we are suddenly awoken from a dream, especially a nightmare, the paralysis continues for a while, even preventing attempts to cry out, and adding to the frightening experience.


The paralysis is absent during non-dreaming sleep. Here, sleepwalking and sleeptalking can occur, which is usually during the deepest form of non-dreaming sleep. Sleepwalkers are in a world of their own, engrossed, unresponsive, and often searching for something known only to themselves. They are difficult to arouse, more than from dreaming sleep. Leave them asleep and quietly usher them back to bed.


Dream-like sensations can occur at the twilight level of consciousness when we fall asleep or wake up in the morning. This is “hypnagogia”, not dreaming, and is commonly found in children. It is under conscious control and usually consists of pleasant images and absorbing thoughts which are more sedate and less spectacular than dreaming, and without any sustained theme. Sensations of floating or slowly falling are common, sometimes accompanied by vague sounds, or even music. Unfortunately this reverie may end abruptly with a sudden jerk or kick of the lower leg, and a startled awakening.


Lucid Dreaming

Some people can actually control their dreams, in a state called ‘lucid dreaming’, although, in many cases it is just hypnagogia. Nevertheless, most of us have probably experienced at least one lucid dream in our lives. It is a rare and unforgettable event, whereby the bizarreness of an ordinary dream seems to make the dreamer begin to ‘realise’ that this can’t be real, and the lucidity is triggered. Then, the dreamer not only knows that he or she is dreaming, but somehow can manipulate the dream according to their wishes, and maintain this enjoyable state for many minutes. The strange fact is that the dreamer seems to be in full possession of his or her faculties, and can act voluntarily in the dream whilst remaining soundly asleep in this incredibly real dream world. Lucid dreaming can even occur towards the end of a nightmare, when the dreamer realises that it is only a dream and decides to stay with it, determined to play out the end according to their script. Needless to say, dream researchers have tried to develop various learning techniques to promote lucid dreaming. There are even biofeedback devices producing light flashes through the eyelids, attempting to signal to the dreamer to ‘get lucid’. Clear accounts of lucid dreaming go back thousands of years. Even Aristotle experienced and reported it, emphatically dismissing the view of the time that this was a sign of madness or a message from the gods. Nowadays, though, profound scepticism prevails, and most sleep researchers are dismissive of lucid dreaming, believing it indeed to be to be purely imaginary, doubting that the sleeping brain is capable of such a sophisticated level of control.


Remembering Dreams

So, to return to the common or garden everyday dream, which everyone experiences. It is usually in colour, but the image soon fades into ‘black and white’, and within about ten minutes it completely disappears unless we happen to wake up and make a real effort to remember. Dreams are not over in a flash, but run their full course in time, with some lasting for over half an hour. External sounds can be incorporated into the dream, partly because dreaming is a light form of sleep whereby the sleeper is vaguely aware of the surroundings. Unless these sensations are perceived to be alarming the sleeper will just dream on.


One of the odd findings with dreaming it that within seconds of suddenly awakening from a dream we are usually fully alert and responsive. If dreaming was a vital state of brain recovery as is often believed, then this sudden awakening would be expected to cause confusion until the brain fully reverted to wakefulness. However, this type of confusion does happen when we are suddenly awoken from the deep form of non-dreaming sleep.


The parts of the brain controlling our emotions seem to be shut down during dreaming, which may be why the dreamer usually experiences an emotional detachment from the events – being more of an impartial observer. This is why we can remain asleep, despite alarming, even frightening experiences within the dream. Sometimes, a vague emotional residue can remain – of happiness, sadness or, more likely, nothing at all. Occasionally, as in a nightmare, this guardian of sleep can no longer contain the emotions and we wake up. Whereas nightmares are the culmination of a frightening dream, they are quite distinct from ‘night terrors’, which suddenly appear out of deep non-dreaming sleep. In a night terror, the sufferer typically sits up suddenly and screams, often reliving a near death or horrifying experience. The fear and panic can continue for many minutes, especially in children, who need much calming down by the even more distressed parent. Strangely, unlike the parent, the child will have little recollection of any of this the next morning.


People claiming never to dream invariably dream as much as anyone else. The reason is that they are usually good sleepers, sleeping uninterrupted through the night, eventually awakening from non-dreaming sleep in the morning. Despite the common belief that dreams are essential for normal mental health, by resolving inner conflicts, discharging tensions or in some way ‘regulating the psyche’, there is no solid evidence to support this appealing theory of Freud and others. In fact, dreaming can make matters far worse. For example, people with depression tend to have sad and miserable dreams which, unbeknown to the sufferer, may lead to more sad thoughts the next day. This is why it may be best that they do not dream at all and, interestingly, many of the successfully used drugs prescribed for depression also knock out dreaming sleep. Patients treated this way have little or no dreaming sleep for the duration of their drug therapy, which usually continues for many weeks until the depression remits. There are well documented cases of such patients having no REM sleep for over a year. Their mental health improves and there are no psychological consequences. In particular, their memory remains quite intact. If dreaming was critical to memory, as some believe, then this treatment should have had a catastrophic effect on the ability to remember, which is clearly not the case.


Why Dream ?

We have no idea whether new-born babies dream in their own peculiar way. But they certainly have lots of REM sleep, which is even more prolific in the month before birth, when the unborn baby has about 10 hours REM sleep per 24 hours. After birth, REM sleep declines rapidly in the first month, falling to about five hours a day after one year. The first year of life is a time of intense learning, and if REM or dreaming sleep were essential to the learning process, then the large fall in REM sleep runs counter to this notion.


REM sleep is found in almost all mammals and, to a limited extent, in birds. We can only surmise about the extent of their dreaming. It would be arrogant to claim that only humans dream. Many dog owners watching their sleeping pets twitch and yelp would certainly argue otherwise. To some extent REM sleep and dreaming are a luxury, as predators and other safe sleeping mammals display much more REM sleep than do their mammalian prey. The lion can sleep and dream for as long as it wants, whereas the antelope has little of either.


So why do we dream ? During non-dreaming sleep the brain probably rests and recovers from the wear and tear of wakefulness. But it does not like being unconscious for too long and needs periodic stimulation to keep it in tune. Rather than having to wake up repeatedly during sleep to achieve this, REM sleep and dreaming may well provide some sort of substitute stimulation for the brain, and maintaining the continuity of sleep. It may well be the reason for so much REM sleep before birth, to make up for the lack of sensory stimulation for the baby before it is born.


Most dreams are mundane, involving unknown scenery and strangers, with the scenario being an everyday scene or mishap, and the dreamer is usually participating in some way. Maybe dream interpretation is still best summed up by the disheartened Freud in his “New Introductory Lectures on Psychoanalysis” published in 1933 : “But if you ask how much of dream interpretation has been accepted by outsiders – by the many psychiatrists and psychotherapists who warm their pot of soup at our fire (incidentally without being very grateful for our hospitality), by what are described as educated people, who are in the habit of assimilating the more striking findings of science, by the literary men and by the public at large – the reply gives little cause for satisfaction” (p8).