Humans do it, birds do it, fish do it. Almost all living things in the animal kingdom sleep, and for good reason. Modern science has established beyond any doubt that sleep is a most essential biological process that helps the brain to ‘rest’ and store memories that have been accumulated through the day. During sleep, our brain washes off all insignificant memories so that it is yet again ready to receive whole new set of sensory inputs when we awaken the next morning.

Mastering Sleep , a book by physician-cum-neuroscientist Swami Subramaniam, gives us some valuable insights into the significance of sleep in our everyday life as well as in helping humans evolve as the most prominent animal species on earth. It also takes us through the scientific journey that made us possible to comprehend its relevance in healthy living.

Recently, a market study by a private concern selling products which it claimed would help their users get a better night’s sleep said nearly 90 per cent Indians are sleep-deprived. The scientific rigours of this study are rather unknown. While the numbers can be debatable, it is a fact that in the modern society — in which gizmos and punishing schedules rule — a large number of people suffer from sleep deficit — either temporary or long-lasting.

The author likens sleep to a bank account whose temporary depletion can be offset by increasing deposits to a large extent. The book quotes a study which estimated that sleep-related issues cost national economies somewhere between 1.4 and 2.9 per cent of their GDP — much more than the economic impact of metabolic disorders. The author also argues that sleep has had an important role in making what we are today as a species. Basing his facts on sound scientific studies of the past, he informs us that humans’ ability to master short, deep sleep was one of the critical factors that made us smarter than most mammals of higher order. Two other major factors, of course, being bipedalism and speech.

“Sleep and genetically-driven evolution of the larynx and the brain may have co-evolved with the social and cultural patterns adopted by the species. Together these constitute a powerful feed-forward mechanism that accelerates genetic adaptation for desirable characteristics like memory and intelligence,” Subramaniam argues.

Mastering the art

Paleo-archaeologists and anthropologists studying early ancient human societies have stumbled upon enough evidence to suggest that our ancestors lived tens of thousands of years ago had mastered the art of efficient sleep. This, the scientists argue, would have helped them sharpen their learning and cognitive skills making them more efficient hunters, tool makers and leaders. One such prominent evidence emerged from Tongati river basin in the province of Kwazulu Natal in South Africa.

Exactly a decade ago, archaeologists who scoured an early human settlement of 70,000 years ago inside a secured cavern were surprised to find mattresses made of foliage, which included leaves of medicinal plants which kept insects away. These “biomattresses” of three metres in length and breadth and a thickness of 30 centimetres, and resembled modern-day springy mattresses, would have helped the members of the tribe to get sound sleep.

In its quest for giving us an overall picture of sleep, the book also throws some light on to sleep patterns adopted by various animal species. It is interesting to note how dolphins, which come to the sea surface for breathing, alternatively shut half the brain at the time of sleep and how migratory birds sleep while flying.

Research into science of sleep has been an active area of study. While sleep is believed to be a process that would give some rest to the body and also to the brain, the brain still remains active during the sleep. The activity of the brain can be gauged and even quantified using a technique called electroencephalography (EEG) by Hans Berger, a German psychiatrist in the 1920s. While Berger made the first-ever EEG recording in the mid-1920s, it wasn’t possible unless there were significant contributions by others, particularly Italian scientist Luigi Galvani, who in the 18th century discovered that neuro-muscular systems in animals generate and carry electricity.

There is an interesting aside about the brain. The brain may be the highest energy expending organ in human body. But still, it is highly economical. It is said to spend energy equivalent of nearly 20 watts every hour. In comparison, a powerful supercomputer needs nearly 2,00,000 times more energy to run.

Sleep deprivation

The book also delves extensively upon sleep deprivation. How many hours of sleep are absolutely essential to keep our body and mind healthy? There are many who claim that they can get by sleeping fewer hours than what are normally prescribed. For instance, our Prime Minister Narendra Modi was on record that he sleeps only four hours a day. While there can be some exceptions, sleep deprivation has serious consequences. A large number of road and industrial accidents occur on account of sleep deprivation. The book indicates how investigations have pointed out sleep deprivation may have been a contributing factor in the deadly Bhopal Gas tragedy, which claimed 3,000 innocent lives or in the 1986 Chernobyl nuclear disaster, where it came out clearly that the night-duty staff did not follow proper procedures.

Many road accidents are attributed to drivers sleeping at the wheel. The cockpit voice recorder of the Air India flight that crashed in the Mangaluru airport in May 2010 killing 158 passengers had picked up sounds of the captain snoring for about half the duration of the flight.

Mastering Sleep deals with a subject that everybody experiences on a daily basis, but still knows very little about. It engages both those specialists who are interested in knowing more about our brain as well as lay readers. The book is sprinkled with ample anecdotal evidence that would make the reading interesting.


Swami Subramaniam is a physician, pharmacologist, and nueroscientist. A PhD from the University of Pennsylvania, he has published papers on brain chemistry relating to learning and memory as well as on conditions such as stroke and epilepsy


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