Emeritus professor Philippa Gander is a sleep expert. She was the inaugural director of the Sleep/Wake Research Centre at Massey University and was made an Officer of the New Zealand Order of Merit for services to the study of sleep and fatigue. The following is an excerpt from her curious little book Night Owls and Early Birds: Rhythms of Life on a Rotating Planet.

An older story

In 1995, Nathaniel Kleitman gave a memorable presentation at his hundredth birthday celebration, during the annual meeting of the Associated Professional Sleep Societies in Nashville. I recall a little old man going up to the podium with pages of large-print notes, which he didn’t look at during his speech. Among other things, he spoke about the discovery of REM sleep, but what has stayed with me most was his enduring passion and enthusiasm for research into the mysteries of sleep.

In a session later that day, I was chatting with an older physician from India who suggested that I should read the Upanishads, the texts at the spiritual core of Hinduism that are thought to be over 2500 years old. In these beautiful texts (in English translation), I found multiple references to dreaming sleep and deep non-dreaming sleep, as in the following examples. (In each, “the Self” refers to pure consciousness, the Brahman.)

In the Aitareya Upanishad:

The Self being unknown, all three states of the soul are but dreaming – waking, dreaming, and dreamless sleep. In each of these dwells the Self: the eye is His dwelling place while we wake, the mind is His dwelling place while we dream, the lotus of the heart is His dwelling place while we sleep the dreamless sleep.

In the Kaivalya Upanishad:

He, as the Self, resides in all forms, but is veiled by ignorance. When He is in the state of dream that men call waking, he becomes the individual self and enjoys food, drink and many other pleasures. When he is in the state of dream that men call dreaming, he is happy or miserable because of the creations of his mind. And when he is in the state of mind that men call dreamless sleep, he is overcome by darkness, he experiences nothing, he enjoys rest.

The pioneering French sleep scientist Michel Jouvet speculated, albeit with reservations, that a painting in the Lascaux Caves (dated around 17,000 BCE) might indicate that some early modern humans (Cro-Magnons) understood another physiological aspect of dreaming. Erections (clitoral tumescence in women) occur regularly during REM sleep, irrespective of dream content. Jouvet identified four elements in this painting and proposed that the artist wanted to simultaneously represent the dreamer, the concept of dreaming, and the content of the dream. There is the man lying on his back with an erection, indicating that he is dreaming. There is a bird mounted on a staff, which could represent the soul of the man leaving his body while he is dreaming (like Ba in ancient Egyptian mythology). Next to the man is an injured bison whose intestines are spilling from its stomach, and beside it a broken spear. These could represent what the man was dreaming about.

These examples stay with me as a reminder that knowledge based on repeatable “objective” measurements in the outside world – the sort of knowledge that I contribute to as a quantitative scientist – does not capture the full extent of human understanding and experience. This is also clear in research on the content and functions of dreaming, where essential data come from the subjective dream recall of participants.

Dreams as data

For much of recorded history, dreams were thought to contain important, even prophetic messages that could not be accessed any other way, and they were often attributed to an external source. Until the identification of REM sleep and its association with dreaming, the only source of information about dreaming was people’s waking recall of what they had “experienced”.

Most of us probably dream regularly, since people whose sleep is monitored using polysomnography typically have REM sleep. However, the brain systems responsible for recent memory are turned off during REM, so dreams are seldom recalled unless you wake up from them. Thus, dreams remembered after spontaneous waking are only a small sample of our nightly ventures into this other form of consciousness. Nevertheless, dream journals remain an important source of data for dream research. 

Another way of gleaning information about dreaming is to use polysomnography to monitor people’s sleep in the laboratory and systematically wake them up from REM sleep to report on what they remember. Dream recall is more consistent in this setting, but there are also some differences in reports gathered in this way, compared to dream recall after spontaneous awakenings. Not surprisingly, people woken from REM sleep in the laboratory often report thoughts, feelings, and precepts relating to the laboratory situation. However, they still report the hallucinations, delusions, and bizarreness that characterise dreams recalled after spontaneous awakenings. The emotional content also seems to be more positive overall in dreams reported when people are woken from REM sleep in the laboratory, compared to reports after spontaneous awakenings at home.

A method that overcomes some of these challenges is to monitor participants’ sleep at home so that the sleep state that they wake from spontaneously (REM or NREM) can be identified later and matched with their reports of what they recall experiencing immediately before each awakening. Participants can also be beeped when they are awake and asked to report on their waking consciousness. 

Harvard psychiatrist Allan Hobson, one of the most influential modern dream researchers, has argued that for dreaming to be studied scientifically, we must shift away from the traditional focus on trying to interpret the content of dreams. Instead of asking “what does a dream mean?”, we need to ask “what are the mental characteristics of dreaming that distinguish it from waking?”. This puts the focus on the formal properties of dreams – how we perceive things (perception), how we think (cognition), and how we feel (emotion) in dreams. In this paradigm, dreaming is a mental experience associated with REM sleep and its characteristic activation in some areas of the brain, deactivation in others, and changes in the connectivity among different brain areas. There are other forms of mental activation during NREM and when falling asleep, but they do not have the same formal properties as REM dreams.

Psychologist Roslyn Cartwright earned the nickname “the Queen of Dreams”. In her superb 2010 book The Twenty-Four-Hour Mind, she argued that it is time to put together what has been learned about the sleeping mind with what psychologists know about waking cognitive and emotional behaviours. She provided a beautiful summary of the two parts of this circadian rhythm in our emotional lives:

All day the conscious mind goes about its work planning, remembering, and choosing, or just keeping the shop running as usual. On balance, we humans are more action oriented by day. We stay busy doing, but in the inaction of sleep we turn inward to review and evaluate the implications of our day, and the input of those new perceptions, learnings and – most important – emotions about what we have experienced.

Cartwright died at the age of 98 during the writing of this book. She is acknowledged as a pioneer in the study of the links between dreaming and REM sleep and a trailblazer for women in sleep science. Her view of the role of dreams in the 24-hour mind was that they serve to regulate emotion and update the self. At the time of this writing, an overview in the latest edition of the major textbook Principles and Practice of Sleep Medicine concluded that research on dreaming is still “a field that is very much a work in progress”.

Night Owls and Early Birds: Rhythms of Life on a Rotating Planet by Philippa Gander (Auckland University Press, $40) can be purchased from Unity Books Wellington and Auckland.