The Good Sleep

The invitation to comment on a book, in addition to being a challenge, is an honor that awakens in one the fear that reading the text may disappoint us.  Very  far  from  that,  my  perception  of  this text,  recently  published,  is  at  the  opposite  end of the spectrum, because it seems to me to be an enormous contribution. Its cover, which is visually very attractive, is promising and foreshadows a good content about what Sophocles called the only effective medicine: sleep. To state, as the famous Greek poet did, that sleep is the only effective medicine is an excessive but illuminating claim in present days, when people are so often looking for safe, inexpensive, and hopefully natural therapeutic alternatives for their ailments.

As we know, sleeping and dreaming have been part of life in the animal kingdom since ancient times. Although   animals   (non-humans   and   humans) do  not  feed,  reproduce  or  forage  during  sleep, and are vulnerable to predators, the persistence of the act of sleeping throughout evolution, and the detrimental effects of sleep deprivation, have enlightened us about its enormous value. Dr. Castillo’s book focuses on the vital experience of human sleep and its alterations. Using a simple, direct and entertaining language , he introduces us to the different topics. In the first part, he goes from addressing general aspects and characterizing the different stages of normal sleep, and “long” and “short” sleepers, to describing the risk factors that predispose sleep disorders. He then continues with an interesting and very compelling chapter on the circadian rhythm that shows us how activities related to our functioning as human beings, particularly sleeping, have a daily rhythm that is linked to the presence and absence of sunlight. We learn that we can influence this circadian cycle by modifying our exposure to light, something so cheap and easy to do, and that physical activity can affect the quality of our sleep.

Then, it talks about insomnia, and we learn that the people of Santiago are the individuals with the worst sleep quality throughout the capitals of South America and are also the largest consumers of sleeping pills. In this matter, we know that animals have an evolutionary ability to develop a mechanism that prevents sleep when a threat approaches (such as the presence of a predator or a dangerous congener). So it is worth asking: to what extent are the potentially adaptive solutions of our inherited past operating as a mechanism that generates or perpetuates insomnia in Chileans? Everything shows that the current feeling of fear and despair of many of the citizens of this country, and their poor sleep quality, is influenced by the feeling of constant threat that seems to be lurking just around the corner.

In fact, in other latitudes some of the issues raised by    this  book  are  being  studied.  For  example, the issue of how disparities in health relate to disparities in sleep quality and the effects that this entails. Predictably, sleep problems are greater in the most neglected neighborhoods of large cities and in some areas it becomes dramatic if bullets and fireworks interrupt nightly sleep on a daily basis.  This  is  why,  projects  in  other  countries that are bringing together sleep specialists, public health  experts,  economists  and  anthropologists are emerging. These are initiatives that our health authorities and medical societies should replicate if we want to sleep better.

The next two chapters will surely be innovative and very appealing to the general public and even to physicians because they deal with less known aspects of pathological sleep. The first one focuses on the so-called hypersomnias and includes two educational clinical cases. The second focuses on parasomnias, a name that gathers, among other disorders, curious conditions such as sleepwalking, night terror, sexsomnia and restless legs syndrome.

Next, the author singles out the essentials of sleep in each of the different stages of life, which will be very useful for the reader to understand their sleep needs and also, to empathize with those of their relatives and friends. .

Finally, the last chapter is dedicated to a diverse group of special topics, of daily occurrence or concern, such as sleep and work aspects, naps, the use of applications and mobile devices, etc. Least but not last, it addresses, with skill and clarity, the act of dreaming in the current long and tedious COVID-19 pandemic.

As a psychiatrist, I cannot fail to mention that the prevalence of sleep disorders is disproportionately high among psychiatric patients and that in the last decade we have moved from conceiving the co- occurrence of insomnia and medical/psychiatric disorders as the result of unidirectional causality to a model of autonomic disorders that interact in a bidirectional way.   So we know, for example, that insomnia can promote depression and, in turn, depression can cause insomnia.

I also think it is important to highlight the link between REM sleep (associated with dream activity) with creativity, as well as the relationship between REM sleep and dream activity with the preparation for a good life, given that REM sleep allows the nocturnal reduction of the reactivity of the cerebral amygdala, with all the benefits that this entails, by allowing us to remember negative events but without having to re-experience its intensity every time it is remembered.

In short, we can say that Dr. Castillo offers us a fast, attractive and up-to-date text that will surely help people with sleep disorders, health students and professionals.   In an age of information overabundance, easy access to trusted expert knowledge is appreciated.