‘Dreaming of Sleep’ (Je rêve de dormir) was published in 2016 on the tenth anniversary of the Centre for Investigation and Research in Sleep, the busiest centre in Switzerland for patient consultations. Adopting a humorous approach, Raphaël Heinzer and José Haba-Rubio tackle a few myths and realities surrounding the work of the sandman.
We spend one third of our lives cradled in the arms of Morpheus. Aside from its physiological aspects, the way we sleep is also a product of our civilisation. Raphaël Heinzer and José Haba-Rubio, Director and Associate Director respectively of the Centre for Investigation and Research in Sleep at Lausanne University Hospital and senior lecturers and clinical researchers at the University of Lausanne, indulge here in a true-and-false exercise, gently mocking certain preconceived ideas.
Each hour’s sleep before midnight is worth two after. FICTION
Raphaël Heinzer: This is indeed what our mothers told us. A sleep cycle is made up of several stages. After falling asleep, we begin a period of light sleep, followed by deep sleep and finally paradoxical sleep. This sequence generally recurs four or five times, but the cycles are not all the same. The first two comprise more of the deep, recuperative type of sleep. It’s at the start of the night therefore that the brain gets most rest, whether or not you go to bed before midnight! What matters most is the regularity of sleep.
We dream more just before waking up. FACT
José Haba-Rubio: We dream throughout the night; the brain never shuts off. But the richest, most colourful and elaborate mental activity takes place during paradoxical sleep, which is more intense and longer at the end of the night. It is therefore easier to remember one’s dreams if one wakes in the early morning after having slept well than if one wakes during the initial hours after going to bed, when deep sleep predominates. Thoughts are more fragmented then and are more like flashbacks.
We sleep less with age. FACT
R. H.: Older people have more broken nights and wake up more. The time effectively spent sleeping is therefore shorter. We conducted a cohort study entitled ‘HypnoLaus’ involving 2162 Lausanne residents aged between 40 and 85 years. Objective measuring using an electroencephalogram showed that older patients had worse nights than younger ones. But curiously, the older ones complained less of feeling drowsy during the day. There is therefore a discrepancy between the objective quality of sleep – which is poor – and the subjective perception of it – which is good. This may be due to the fact that this population group is subject to fewer constraints during the day and is less stressed by a performance target.
Eight hours of sleep is essential. FICTION
R. H.: This is a question of a statistical average. The need for sleep varies from one person to another. Some patients complain of insomnia because they can manage just six hours sleep a night instead of the commonly recommended eight. When they are asked if they are tired during the day, they confirm that they are not. These subjects are not insomniacs but simply sleep little. It is important to understand one’s sleep needs. We advise patients to carry out a test when on holiday. After a few days to catch up on any sleep ‘deficit’, we encourage them to go to bed when they are tired and to wake up naturally without an alarm. Some note that six hours are sufficient, while others need nine hours to be on form.
A long lie-in at the weekend makes up for a lack of sleep during the week. FACT & FICTION
J. H.-R.: You cannot sleep longer at will. If your body is capable of ‘producing’ more sleep, it’s because during the week you’ve accumulated a certain ‘deficit’ that you will make up when you have the chance.
R. H.: It’s important to pay attention to this yo-yo rhythm – deprivation during the week and recuperation at the weekend. This places a stress on the body that may ultimately increase the risk of hypertension, cardiovascular disease or diabetes. Researchers in Sweden, for example, noted that the heart-attack rate was slightly raised on the Monday following the change from winter to summer time, when an hour’s sleep was ‘lost’.
Plants sleep. FACT
R. H.: They have a rhythm of activity. Some plants extend their leaves during the day and curl them up at night and do so even when confined to a black box without sunlight. Thus it’s not the effect of light which produces the movement but a sort of internal biological clock. The latter is normally synchronised with the rhythm of the day and night, but clearly continues to function even if the plant is continuously in the dark.
Waking up at night is a sign of a system malfunction. FICTION
J. H.-R.: We waken between twenty and thirty times a night. This is probably related to reflexes that date from the distant past when we were cave-dwellers and were easy prey. These short periods of wakefulness allow us to verify that all is well. Practices have evolved over time too. The current norm is for monophasic sleep: we sleep in one single span. Yet up until the end of the eighteenth century, biphasic sleep was quite normal. Our ancestors went to bed at nightfall, slept for three to four hours then woke up for one to two hours before going back to bed. Today, for social and technical reasons – the invention of electricity – we practise ‘single-span’ sleep, which in principle is continuous. Nocturnal waking, which is quite normal from a physiological point of view, has become a source of stress. People who sleep badly are often those who are afraid of sleeping badly.
The full moon has an effect on sleep. FICTION
J. H.-R.: This is a myth, again perhaps inherited from a time when we were living in caves and the light of the full moon made us more visible and therefore more vulnerable. By retrospectively examining the sleep measurements collected as part of the ‘HypnoLaus’ study, we found no significant correlation between the quality of sleep and the different phases of the moon.
R. H.: Something that might give the impression of having slept badly on a night when there was a full moon is that these are the nights that we remember! We refer to that as ‘recall bias’. When we sleep badly and see the full moon, this creates a causal link in our minds. But if we observe nothing or just a tiny crescent moon, we don’t remember it.
Snoring has a negative impact on sleep quality. FACT & FICTION
R. H.: It certainly does on that of a partner or spouse. But more seriously, snoring is not regarded as an illness per se. It occurs when a narrowing of the throat prevents the passage of air and creates turbulence. This turbulence causes the soft palate to vibrate, creating the noise that typifies snoring. If the narrowing is significant, the person must make an effort to make the air pass through to the lungs and this can result in nocturnal awakenings. And some people suffer from complete closure of the throat – obstructive sleep apnoea – resulting in a lack of oxygen and sudden awakenings brought on by a feeling of suffocation. In extreme cases, this can happen more than 100 times in an hour! Not only is sleep poor as a result but, in addition, each asphyxiation releases adrenalin. The stress created can have serious consequences: for example, the risk of a stroke is doubled. It is the apnoea which above all poses a problem; snoring itself has no consequences for health.
Electromagnetic waves have a negative influence on sleep. FICTION
J. H.-R.: Objective studies in the lab show that electromagnetic waves have a minimal effect on the brain’s electrical activity and in reality make falling asleep happen faster. The light or sound emitted by mobiles certainly disturbs sleep more than the waves they emit.