Just imagine if you could wake up to this announcement: ‘Today is cancelled, go back to bed!’ Wouldn’t it be wonderful?
Breathing, drinking, eating and sleeping — these are the four most important things that we do to stay alive. Of all these processes, sleep is the most enjoyable… and also the most enigmatic one. On average, we sleep for 2,29,961 hours in our lifetime, or for 25 years — basically one-third of our lives. So, sit up! We’ve got a lot to explore.
Here is an evolutionary paradox — we need sleep to survive, yet when asleep, we render ourselves vulnerable to predators. Two, isn’t spending time being inactive, unaware and useless, a waste of time, a luxury? So, why are we invested so heavily in this process that takes away our precious short time on earth?
Why do we sleep? Simple. Because a bed is precious real estate and we want to make good on our investment. Oh, you want the scientific reason? Well, here it is. Sleep is a state of altered consciousness when many housekeeping functions of the body occur. “No species can function at its best over a 24-hour period,” says Russell Foster, professor of Circadian Neuroscience at the University of Oxford.
The body has to take a break from normal activity to perform a lot of critical functions, especially in the brain. Students, remember that memory-formation happens best when there is less interference, therefore, if you sleep after learning something new, you are more apt to remember it better. Everyone else, the brain continues work on problems even while you’re asleep, so while trawling for solutions, it is a good idea to ‘sleep on it’.
A good night’s sleep also ‘clears the cobwebs from the brain’, almost literally. Unwanted toxins are cleared from the brain during sleep, since the glymphatic system run by glial cells, which support and protect brain cells, is especially more active during sleep. “Therefore, good sleep is a contributor to good brain health,” say researchers. Symptoms of neurological diseases such as Alzheimer’s and Parkinson’s worsen with lack of sleep — ‘no sleep for the wicked’, indeed.
When we ‘hit the sack’, we ‘sleep like the dead’, meaning, our muscles undergo temporary paralysis. The sympathetic nervous system or the activator of the fight-or-flight mechanism relaxes. A number of different hormones like melatonin from the pineal gland and growth hormones from the pituitary gland are secreted, which help in sleep and in growth and body repair. Levels of cortisol or stress hormone decrease during the early hours of sleep, making us relaxed and refreshed by our ‘beauty sleep’.
Its lack...
However, if we’re unable to ‘get a wink of sleep’, we increase the risk of disorders including high blood pressure, cardiovascular disease, diabetes, depression and obesity.
So, to say that sleep is essential is a no-brainer. However, sleep kept its secrets until recently. Around 450 BC, a Greek physician, Alcmaeon, postulated that sleep was a period of unconsciousness caused by blood draining from the body surface. Aristotle thought that it was unconsciousness caused in the heart, and connected it to the digestive process. In 162 AD, Galen, another Greek physician, identified the brain as the seat of consciousness. In 1916, a region of the brain called hypothalamus was identified as the centre of sleep and wake activity. Then, in 1924, the electroencephalogram was invented to record the electrical waves in the brain.
In 1953, a graduate student at the University of Chicago named Eugene Aserinsky spent hours studying the eyelids of sleeping subjects (Yes, these people were paid. What a dream job!). He and his PhD adviser, Nathaneil Kleitman, then went on to demonstrate that the rapid eye movement they observed was correlated with dreaming and a general increase in brain activity. Hence, they are considered the founders of modern sleep research.
When we ‘hit the hay’, we go through two basic types of sleep — rapid eye movement sleep and non-REM sleep. The first stage is the non-REM sleep where we move from wakefulness to sleep, when our brain waves begin to slow. The next stage is non-REM sleep, a period of light sleep before we enter deeper sleep. Stage 3 non-REM sleep is the period of deep sleep that is needed to feel refreshed in the morning.
It is hard to wake up in this period. Then, REM sleep begins to occur, about 90 minutes after falling asleep. During this, brain wave activity becomes closer to that seen in wakefulness. We cycle through all these stages of these two types of sleep several times all through a typical night.
Unfortunately, this sleep-cycling is all the exercise some of us get.
Diurnal creatures, those that stay awake during the day, are programmed to ‘go to bed with the sun’. Our biological clock, which is based on a 24-hour day, controls our daily alternating between wakefulness and sleep. Known as the circadian rhythm, it synchronises with environmental cues of light and temperature during different times of the day, but continues even in their absence. For example, even if we moved into dark caves full-time, we’d follow roughly the same sleep-wake cycle. However, our circadian rhythm goes out of sync when we fly into a different time zone, creating a mismatch between our body clock and the actual clock, resulting in jet lag. Hmmm, wonder if this is what happens on Monday mornings as well.
Do you ‘burn the candle at both ends’, meaning, you sleep late and wake up early? Don’t, because it interferes with your sleep-wake homeostasis that reminds the body to sleep after a certain time and regulates sleep intensity. This is governed by the state of health, stress levels, sleep environment, what you drink and eat, and importantly, exposure to light. Constant exposure to light can disorient the body and disrupt the sleep cycle. This is why night-shift workers have trouble falling asleep during the day and staying awake during work at night. (If you have this problem, listen to a class lecture on your least favourite subject. Guaranteed sleep in five minutes.)
Living in the 21st century, we are all used to the idea of functioning all day and sleeping for eight hours a night. However, this is not how we evolved. Instead of having a monophasic sleep pattern, human beings had a biphasic or polyphasic sleep pattern. We are all aware of catnapping or catching 40 winks during the afternoon. However, early man would go to sleep with the sun. After a few hours of sleep, he would wake up, socialise or perform some activities. An hour or so later, he would go back to sleep and wake when the sun came up. Historical literature talks of ‘the first sleep’ and ‘second sleep’, showing that this form of biphasic sleep was the norm earlier in our evolution. Some tribes of Africa still follow this pattern. So do some teenagers… who also enjoy ‘third sleep’, ‘fourth sleep’ and so on.
Different wiring
Ever get upset with someone because they are ‘night owls’ and like to stay up late, or ‘early birds’ and wake up at the crack of dawn? Well, different people are wired differently, and have different sleep habits. But it’s always best to let sleeping dogs lie and not to tickle the sleeping dragon, because dogs or dragons may not have the best sense of humour when woken up during non-REM sleep.
And the advice ‘Don’t wake a sleeping bear’ should be taken literally. Hibernation is when some animals like bears, mice, frogs and hedgehogs find a warm sheltered environment during long cold winter months in which to avoid extremely low temperatures. During this period, the animals have reduced heart rates and blood flow, and drastically reduce their metabolic rates. During these periods, their body temperature may even drop by as much as 63 degrees Fahrenheit.
However, bears are not true hibernators. Instead, they are said to be in torpor. They do lower their metabolic rates, and do not eat or drink or urinate or defecate. But they aren’t actually asleep the whole time. Hibernating bears may occasionally leave their dens or even get up and move around. But most importantly, the physiological changes they undergo are very different from those that happen during sleep. True hibernators will not wake up when they hear a loud noise or even if they are moved or touched. So bears hibernate as an energy-conservation mechanism, not a sleep mechanism, so they can wake up. The worst part is this — they wake up hungry!
Yoga nidra or yogic sleep is not true sleep, either. It is a state of consciousness between waking and sleeping, like in a going-to-sleep stage. It is said to open deep phases of the mind.
Sleep in stories
Since it forms such an important part of life, sleep is enshrined in mythology too.
In Greek mythology, Hypnos is the god of sleep, hence the term hypnosis. He is the son of Nyx (night) and Erebus (darkness). Interestingly, his twin brother is Thanatos, or Death. His children by Pasithea, the goddess of relaxation and rest, are the Oneiroi or the gods of dreams — Morpheus, Phobetor, Phantasus and Ikelos. It is said that Morpheus slept in a cave full of poppy seeds, the reason why the opium-based medication for severe pain was named Morphine. In Roman mythology, Somnus is sleep and brother of Mors, death. Hence the terms somnolence and insomnia. Hindu mythology, too, has a couple of interesting tales of sleep. In the Ramayana, it says that Ravana and his brothers performed severe penance to gain boons from Brahma the Creator. Ravana asked for immortality and Vibeeshana asked righteousness for himself. When it was the third brother, Kumbhakarna’s turn, the head of the Devas, panicked.
He knew that Kumbhakarna was going to ask for ‘Indrasana’ or the seat of Indra. He begged Saraswathi, the Goddess of Learning, to help him. Saraswathi caused Kumbhakarna to become tongue-tied, making him to misspeak and ask for nidrasana or a bed to sleep on. It is also said that he wanted to ask for nirdevatvam or the destruction of the Devas, but instead asked for nidrevatvam, sleep that lasted for ever. Upon Ravana’s request, this ‘boon’ was mitigated to six months of sleep followed by a day of wakefulness during which he would devour everything in sight and drink gallons of water. When Ravana went to war against Rama, he needed Kumbhakarna’s help. But it had been only nine days since he’d gone to sleep. It is said that 1,000 elephants had to walk over his body to wake him up. Though he was Ravana’s brother, he was righteous and tried to convince him of his wrong-doing. When Ravana proved adamant, he went into battle and created havoc, capturing Sugriva, but was ultimately killed by Rama.
Interestingly, this story was revisited in 2015, as an article in the Indian Journal of Endocrinology and Metabolism discussing a patient who behaved much like Kumbhakarna. This patient had a condition called Hypothalamic obesity, caused by an abnormality in the hypothalamus region of the brain.
Patients with this condition tend to sleep a lot, waking only to eat. They are overweight, tend to drink a lot of water, and also fall into terrible rages. So Kumbhakarna might have had a medical condition!
There is also another story regarding sleep, more specifically, sleep deprivation coupled with devotion. In the Ramayana, Lakshmana’s devotion to his brother Rama is well-documented.
However, little is known about his wife Urmila. While Valmiki makes only a mention of her as being married to Lakshmana, folk versions tell a much more interesting story. Urmila, who is also the sister of Sita, begs to go with her husband to the forest, but Lakshmana refuses, saying that his duty is to care for his brother and his wife and he doesn’t want any distractions. So she agrees to stay on in Ayodhya.
On the first night of exile, while Lakshmana stands guard for Rama and Sita, the goddess of sleep, Nidra Devi appears before him in all her splendour. Lakshmana refuses to go to sleep and begs her to let him stay awake for 14 years.
Nidra Devi agrees, but on one condition. Since it goes against nature for a man not to sleep for 14 years, someone must take on the burden of his sleep. Urmila agrees to take on her husband’s share of sleep so that he might never be fatigued. So she sleeps heavily for 14 years, a state known as Urmila Nidra.
This has an impact in the war against Ravana also.
Ravana’s son Meghanadh had obtained a boon that would make him invincible. Only a man who hadn’t slept for 14 years could kill him. Hence, only Lakshmana was able to kill him, thanks to Urmila. This story ends at the time of Rama’s coronation. Just when Rama is to be crowned king, Lakshmana begins to laugh. When asked the reason for his mirth, he says that Nidra Devi, who had left him alone for 14 years, was now demanding that he go to sleep.
So it is Urmila who gets to witness Rama’s coronation — Lakshmana is asleep then! This story of quiet devotion has captured imaginations to such an extent that there is actually a temple for Lakshmana and Urmila in Bharatpur, Rajasthan.
Sleep jokes, anyone?
For any concept to be validated, there have to be jokes about it. Well, here are some sleep jokes. A wistful wish from a wistful wisher: ‘I want to die peacefully in my sleep like my grandfather … not like the four others in the car with him.’ This is what Betty White had to say about beauty sleep: ‘Get at least eight hours of beauty sleep. Nine if you’re ugly.’ And here is a lament that every student has: ‘If sleep is really good for the brain, why is it not permitted in school?’
Bottom line
Finally, here’s an Irish proverb: A good laugh and a long sleep are two best cures for anything. You’ve had one, it’s time for the other.’ Now what are you waiting for? It is 10 pm somewhere in the world …
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