The other day I counted the word “sleep” in 167 passages of your work and I am sure I did not count them all. You have penned sleep in its own image and as a metaphor. You knew sleep:
“The innocent sleep, sleep that knits up the ravell’d sleeve of care, The death of each day’s life, sore labour’s bath, Balm of hurt minds, great nature’s second course, Chief nourisher in life’s feast.” (Macbeth, Act II)
And you knew sleep’s associated afflictions, especially its deprivation: insomnia.
Enjoy the honey-heavy dew of slumber: Thou hast neither figures nor no fantasies Which busy care draws in the brains of men; Therefore thou sleep’st so sound. (Julius Cæsar, Act II)
The purpose of my letter is to share with you new information we have learned about sleep and insomnia since your demise in 1616.In the intervening four hundred years; we have invented complex contraptions to study a sleeping person. We can record the brain activity, eye movement, muscle tone, breathing patterns and measure the levels of various substances (chemicals, molecules, hormones) floating in the blood. All these studies have yielded considerable information.
We now describe the architecture of sleep according to the movement of the sleeping eyes, which when moving rapidly is the “rapid eye movement” (REM) phase; the rest is the non rapid eye movement phase (NREM). We start our sleep with NREM and get into REM before waking up. NREM starts with easy arousal light sleep (stage1 and 2) and marches into deep sleep (stage 3 and 4) from which a slumbering person is difficult to arouse. The unpleasant experiences of night terrors, sleepwalking and bed-wetting – the afflictions you are familiar with — occur during deep sleep.
Macbeth had a troubled stage 4 sleep:
“Ere we will eat our meal in fear and sleep In the affliction of these terrible dreams That shake us nightly: better be with the dead, Whom we, to gain our peace, have sent to peace, Than on the torture of the mind to lie In restless ecstasy” (Macbeth, act III)
And Lady Macbeth too sleep walked in her deep stage 4 sleep:
“Since his majesty went into the field, I have seen her rise from her bed, throw her night-gown upon her, unlock her closet, take forth paper, fold it,. write upon’t, read it, afterwards seal it, and again return to bed; yet all this while in a most fast sleep.” (Macbeth, Act V)
Mr. Shakespeare, Did Parolles wet his bed in REM sleep or deep sleep?
“In his sleep he does little harm, save to his bed-clothes about him” (Alls Well That Ends Well, Act IV)
The sleep cycle starts with stage1 during which we drift in and out of sleep, our brain activity slows down. Then we enter stage 2: our brain activity slows down further; our muscles may suddenly jerk but our eyes do not move. Stage 3 shows periods of slow moving delta waves on recording of the brain activity and in stage four our muscles are immobile and brain activity reflects only delta waves. REM sleep follows stage 4: the eyes throw jerky movements, blood pressure rises, breathing becomes shallow and rapid, temporary muscle paralysis ensues, heart pounds faster, men get penile erections and the brain waves gather speed. We indulge in dreams during this active stage of sleep — the brain is hardly idle. (Most mammals and birds show REM sleep, but cold blooded animals and reptiles do not. Do other mammals dream?)
Mercutio got it wrong:
“True, I talk of dreams, which are the children of an idle brain” (Romeo and Juliet, Act I)
We sleep in cycles of NREM and REM and about 90 to 100 minutes elapse from the beginning of stage 1 to the end of REM. This cycle repeats 3 to 6 times at night. In a cycle of 100 minutes, the duration of stage 1 is 10 minutes, stage 2 is 50 minutes; stage 3 and 4 is 15 minutes and finally REM lasts 25 minutes. If we miss our REM sleep, we fall into REM the next night without other stages, till we catch up with this REM deficit.
We flash signals from the base of the brain which either awaken us or put us to sleep. These chemical signals or neurotransmitters like serotonin and norepinephrine exude from the nerve cells (neurons) of the brain stem and keep the brain awake. Other neurons at the base of the brain turn off the awakening process and we fall asleep. The levels of adenosine build up while we are awake and subside during sleep. Caffeine containing potions like coffee and tea inhibit adenosine.
REM sleep is regulated by the part of brain — we call Pons, which sends signals to other parts of the brain and also inhibits neurons in the spinal cord causing temporary paralysis.
We have learnt our bodies function in a cyclic rhythm spread over 25 hours: we call it circadian rhythm. Mere 200,000 neurons in the suprachiasmic nucleus (SCN) of hypothalamus play the role of the body clock. Sunlight or other bright light and even external noise triggers SCN which signals the pineal gland to shuts off the production of melatonin. The pineal gland secrets melatonin (a drowsiness inducing hormone) at night and in darkness. Some people with blindness suffer from sleeping disorders because they are unable to respond to light. Traveling long distance in a short period (jet lag) or change of shift at the work place can disrupt the circadian rhythm.
The neuro-chemical control of sleep is autonomous and we can not voluntarily deprive ourselves of sleep. Cleopatra in her raging defiance may have succeeded in starving herself but to defy sleep was an empty threat.
“Sir, I will eat no meat, I’ll not drink, sir; If idle talk will once be necessary, I’ll not sleep neither: this mortal house I’ll ruin, Do Caesar what he can. Know, sir, that I will not wait pinion’d at your master’s court.” (Antony and Cleopatra, Act V)
Voluntary sleep deprivation may not be possible, yet we have enough reasons to loose sleep: anxiety, depression and body pain. Iago could not sleep because of pain…
“And, being troubled with a raging tooth, I could not sleep.” (Othello, Act III)
And King Richard was anxious.
“For never yet one hour in his bed Have I enjoy’d the golden dew of sleep, But have been waked by his timorous dreams.” (King Richard III, Act IV)
In our “progress” we have added a few more causes of insomnia: jet lag, shift change and stimulant drugs. People who work at night and travel through time zones disturb the sunlight stimulus to circadian regulation.
We have found that sleep is essential for survival – at least for rats. Scientists made rats live on a platform floating in tub of water. When rats drifted into REM sleep their muscles got paralyzed and they slipped off the platform and fell into the water. Poor rats! Wet and drenched they struggled and climbed back onto the platform went into paralyzing REM sleep and fell into water again. Deprived repeatedly of REM sleep, they died in 3 weeks instead of usual 2 to 3 years.
Mr. Shakespeare, do you accuse us of being sadistic? We defend the progress of science at all costs! This very scoundrel race of rats spread the germs that devastated London with bubonic plague which must have caused you a few sleep less nights! Well, we people are adept at taking revenge for historical blood feuds; in his case it is against the rats. Well, they are all rats!
You ask what have we achieved in the past 400 years? We have accumulated wealth and information; yet it is true that our restless days still end up in sleepless nights. King Henry also knew it; money can buy you a bed but not sleep.
“Not all these, laid in bed majestical, Can sleep so soundly as the wretched slave, And, but for ceremony, such a wretch, Winding up days with toil and nights with sleep,” (King Henry V, act IV)
You probably think the information gained in the last 400 years has cured our insomnia… not so Mr. Shakespeare: 30 to 50 percent of our people now suffer from insomnia; we are a sleep deprived world. Here is some news for you from the Boston Globe:
The Institute of Medicine report said loss of sleep has increased in recent decades due to longer workdays and computer use and television watching taking up more time. Lack of sleep increases the risk of a variety of health problems, the report said, including diabetes, cardiovascular disease, and heart attacks. It also raises the chances of injury or death due to accidents at work, home, or in automobiles. Studies in the 1990s estimated the cost of medical care for sleep disorders at $15.9 billion, the report said. In addition, fatigue is estimated to cost businesses about $150 billion a year in lost productivity and mishaps, and damage from motor vehicle accidents involving tired drivers amounts to at least $48 billion a year. The National Sleep Foundation issued a report indicating only 20 percent of US adolescents get the recommended nine hours of sleep a night.
So, here we are, four centuries after you! Amazing: so much knowledge, yet how little we have learned! We have coaxed but a few ounces of wisdom from the tons of information we have collected and culled. Our data could fill the cavernous base of a medieval church and all the wisdom will rise but slim as a spire. From you we need to learn to build with in the scaffold of wisdom and not on the foundation of data. We need at least as many seers as we have scientists.
“Not poppy, nor mandragora, nor all the drowsy syrups of the world, Shall ever medicine thee to that sweet sleep, Which thou owedst yesterday.” (Othello, Act III)