Sleep is a cyclical process with its main feature, circadian rhythm, occurring within a period of 24 hours to elaborate this cycling through stages of sleep. Body’s internal clock influences circadian rhythm or “morningness” or “eveningness,” or “lark” versus “owl” tendency which determines many personality traits. According to a study distributed by The American Academy of Sleep Medicine, “About one half of the population are daytime people, about one-quarter are moderate to extreme morning types, and about one-quarter are moderate to extreme evening types - knowing one’s own type is important for workers who want to maximize job performance, productivity and personal health.”
Further research suggests that during sleep there is an accelerated secretion of a particular hormone (Melatonin – also called “hormone of darkness” because it is secreted at night hours of darkness only) by pineal gland in the brain. Melatonin helps us sleep according to sleep researchers. Fluctuations in Melatonin levels influence our desire to stay awake or go to sleep.
During evolution, sunlight exposure determined what our Melatonin levels were. Our bodies still respond to Melatonin in the same way we did thousands of years ago. The difference today is that we now have many other sources of light mimicking sunlight, which upsets our body clocks/sleep cycle disrupting natural cycle of melatonin secretion. In a study of nearly 24,000 women ages 40 to 79 sleep deprived women had a greater incidence of breast cancer than those women who had an adequate amount of sleep. The increased risk may be due to diminished secretion of sleep hormone melatonin.
A PERIOD OF RELATIVE QUIESCENCE
While a lot is now known about sleep, many unchartered areas still remain awaiting to be explored by sleep scientists. This realization led American Medical Association in 1996 to recognize sleep medicine as a specialty and interest in sleep science gradually began to emerge in the medical community.
Sleep science is truly a multi-disciplinary science forming a rainbow of rich hues from the fields of physiology, psychiatry, psychology, cardiology, bio-physics and the list goes on. A slew of research to unravel a number of hidden aspects of sleep in world’s sleep laboratories has now become a high decibel area of research. At least, what is now known about sleep are a number of variations such as it is a period of somewhat ‘quiescence’ when all activity, normally undertaken when we are awake, ceases; and there is a reduced responsiveness to external stimuli. While asleep one is unable to work for living or otherwise, have training or education or do anything involving cognition or take care of young or be able to procreate. Animals cannot forage for food or avoid dangers of predation. Urine gets more concentrated and gastric functions also go down during sleep.
Sleep researchers Kleitman and Aserinsky in 1953 hypothesized that sleep is our natural or passive state of existence and “we must be stimulated into wakefulness by sensory experiences or by muscular activity or else without such stimulation we stay asleep like a stone.” But many other sleep researchers do not align with this concept of sleep as a completely “passive” state and view it as an active state – the very name REM (Rapid Eye Movement – an important phase of sleep) testifies such an activity. German psycho-analyst, Sigmund Freud, in Interpretation of Dreams in 1900 noted that muscles paralyze during sleep that hinder the sleep from acting out of their dreams (barring a few exceptions of sleep-walking or somnambulism.)
Some sleep scientists describe sleep as an interruption of wakefulness. Romanticism of the middle ages and early 20th century has provided many poetical rich hues of sleep. The English bard, William Shakespeare, called sleep “the death of each day’s life” while Homer in Iliad said of “sleep and his twin brother death.” Samuel Johnson, saw sleep as an “irresistible stupefaction” – the absence of overt objective behavior of which a waking individual is capable of. Another writer, Miguel de Cervantes of Don Quixote fame, eulogized sleep in these words: “Blessings light on him who first invented sleep! It covers man all over, body and mind, like a cloak; it is meat to the hungry, drink to the thirsty, heat to the cold, and cold to the hot; it is a coin that can purchase all things; the balance that makes the shepherd equal with the king, the fool with the wise man.” And to quote Ernest Hemingway, “I love sleep. My life has a tendency to fall apart when I’m awake, you know? Cervantes’s Sancho song praised sleep, “the food that cures all hunger, the water that quenches all thirst, the fire that warms the cold, the cold that cools the heart…the balancing weight that levels the shepherd with the king, the simple with the wise.
SLEEP IS NOT HIBERNATION
Sleep is not hibernation (from the Latin word hibernates; “to pass winter “) because, unlike hibernation, it is marked by rapid reversibility, and the fact that there is a need for sleep following a period of sleep deprivation to compensate for the time of sleep lost during sleep deprivation. Hibernation may be called extended sleep. It is a condition of spending winter asleep in an almost comatose, torpid or resting state by which some animals conserve their energy.
GENDER ISSUE
Sleep problems among adult women are connected with causes peculiar to their gender – half of them during their menstrual period, three-quarters during pregnancy and child-birth and many attributed to menopause later in life with hot flushes, night sweating and insomnia. Women undergo more sleep changes and more challenges than men because of their hormone issues – for example, during the first trimester of pregnancy the sleep need rises.
A National Sleep Foundation poll (1988) Women and Sleep of all adults revealed that the average woman aged 30 – 60 sleeps only six hours and forty minutes during the weekday, but sleep problems affect them more than men. They report depression twice as much more than men apart from a higher incidence of anxiety, stress, reflux, bladder problem or pain. More women (58%) suffer from nighttime pain than men (48%) according to a 1996 National Sleep Foundation Gallup Poll.
When it comes to older women - because of the onset of menopause, they are at a particular risk of sleep disorders. In fact, “sleep disorders are one of the hallmark symptoms of menopause from one-quarter to one-half of women.” It has also been suggested that estrogen (whose level goes down after menopause) is associated with increased sleep time and decreased number of nighttime arousals.
An interesting question has sometime been raised as to who sleeps better at night – men versus women, and singles versus couples. As reported in Wall Street Journal of June 5, 2012, correspondent Andrea Peterson has this to say,” Couples may get health benefits simply by sleeping in the same bed… In fact, some scientists believe that sleeping with a partner may be a reason why people with close relationships tend to be in better health and live longer.” Women in long term stable relationships fall sleep more quickly and have less number of arousals during the night than single women. The underlying hypothesis suggests that by promoting feeling of security and safety, shared sleep lowers stress hormone (cortisone) and raises love hormones (endorphins) known to ease anxiety.
PHASES OF MOON & SLEEP
The myth (or perhaps a fact) that phases of moon, in particular full moon, affect human sleep, mood, behavior and sanity has survived for a long time in popular folklores of many cultures. But this association has been dismissed as “moonstruck” and “lunatic” in pre-scientific days. Nonetheless, some members of the science community still support this association by correlating sleep data with phases of moon. Recently, this topic was investigated in detail at the Center for Chronobiology at the University of Basel, Switzerland by a group of scientists headed by Dr. Christian Cajochen who looked at the relevant data between 2000 and 2003 on the effect of phases of moon on daily body clock and sleep patterns of 33 healthy men and women volunteers between the ages of 20 and 74 in a sleep laboratory correlating the data on sleep with phases of moon. The results appeared in Current Biology, August 5, 2013. These volunteers were quarantined, shut away from daylight and moonlight for days at a time so that their sleep patterns were not affected by the illumination of a full moon. The findings of the experiment confirmed that the “phase of the moon does affect human sleep patterns, even when the humans cannot possibly see