Sleep is Strange
The reason why we sleep is a mystery, there are plenty of theories and ideas and yet nothing definitive is known. Nearly all animals show electrical activity suggestive of sleep. Dolphins sleep one hemisphere at a time, so they can maintain enough consciousness to breathe and vigilance for predators.
People vary greatly in their sleep patterns. Leonardo da Vinci, supposedly had only 15-minute cat-naps every four hours, while Benjamin Franklin and Thomas Jefferson were often to busy to bother with sleep.
People who have narcolepsy however, are on the other end of the spectrum. This disorder causes excessive sleepiness and sleep attacks and the affected person may fall asleep as they are talking to someone or driving. Within five minutes sufferes of narcolepsy, are straight into REM (Rapid eye movement sleep), while most of us take around an hour to reach the REM stage, when dreaming occurs and the eyes move (to oxygenate them).
People with Narcolepsy often experience very hallucinogenic dreams, sudden loss of muscle tone and sleep paralysis. A person may suddenly fall forward, their jaw will slacken and their knees buckle; strong emotions like anger or laughing can trigger this. The cause of this disorder is the lack of two related brain chemicals called "hypocretin-1" and "hypocretin-2"(orexins). These brain chemical control not only sleep, but also appetite.
A drug which hit the market a few years ago called Modafinil, has the ability to keep you awake or limit the need for sleep without side effects (for most people). College professors and people who want to squeeze more work into a day, have taken to the drug with a passion. This drug has also been used for narcolepsy but increasingly has become a "lifestyle" drug. PET scans however, have shown that Modafinil like most stimulants are blocking dopamine transporters; drugs of addiction like cocaine and amphetamines also work this way, which is a worry.
Ever wondered why after you eat a particularly heavy meal, you feel sleepy? This is also to do with the aforementioned hypocretins. Hypocretin neurons, are found in the hypothalamus (brain) and are turned off by elevations in glucose caused by the heavy meal. If you want to counteract this effect, be alert and loose weight, you have to eat proteins like egg whites. Amino acids in foods like egg whites, prevent glucose from blocking the hypocretins. Hypocretins also explain why you often can't sleep when you are hungry (a nice piece of toast with some honey should do the trick).
Another important sleep chemical is adenosine, which builds up in parts of the brain during waking periods and declines during sleep. Adenosine may also be one of the reasons that you crave your morning cup of coffee, as caffeine stops adenosine from binding to brain cells. This is also why a cup of coffee in the evening can give you insomnia. We need adenosine, which is a cellular metabolic end product, to build up so we feel sleepy at the end of the day.
Sleep also generally conforms to a cycle called a circadian rhythm, which revolves around the daily cycles of light and dark. Circadian rhythms are controlled by clock genes (those who have read “The Time Traveler's Wife” may remember a very tall story about Henry's clock genes) and some varieties of Bipolar disorder have been linked to mutations in clock genes.
Circadian clock genes, are also involved in animals hibernating and bird migrations. Melatonin, is a very important hormone in relation to circadian rhythms and levels can be affected by the seasons due to the amount of sunlight. When it is dark our brain produces melatonin, which is not only important for sleep but also sexual arousal, so keep away from bright lights when you have romance in mind. Melatonin production can be disrupted by shift work, jet lag and even sight problems, and it is also involved in determining women's menstrual cycles (when and how long). Melatonin can be taken as a supplement and is a potent antioxidant.
If you manage to get to sleep, there are still disorders called parasomnias to worry about. Parasomnias which can involve night terrors, sleep walking, sleep paralysis or acting out a violent dream. People with the last type of parasomnia, have been known to attack their bed partners, kicking, scratching and screaming out obscenities, while acting out their dreams (imagine facing this on the wedding night!). Kids often experience night terrors at certain ages and this can involve anything from a blood curdling scream in the middle of the night, going to the toilet in the fridge, to actually jumping out the window. There are treatments for these disorders, but whatever you do stay away from the sleep medications!
Most people have heard stories related to people taking the sleeping medication Stilnox (zolpidem) and doing all kinds of strange things while asleep. One man was arrested and charged with being twice the legal alcohol limit but it seems he was "sleep-driving". Other people have had "sleep sex" while taking the drug (the mind boogles!) so be careful who you share a room with, if you take this drug. Stillnox however, has a better reputation in cases of certain brain injuries. Some people who have been left extremely impaired, have been able to talk and respond again after taking this drug.
Chronic insomnia is a problem that faces many people and stress seems to be involved. In stress states the body can release corticotropin-releasing hormone (CRH) and cortisol, which cause hyperarousal. Interestingly, scientists have found that people who drink black tea are able to reduce the circulating stress hormones, so perhaps a cup of black tea at night is the go. An amino acid called L-theanine, which is in tea has also been shown to increase alpha waves and "relax the mind"
There is so much more to say about sleep but instead I will just add some quotes.
"He that sleeps feels not the tooth-ache."
"I love sleep. My life has the tendency to fall apart when I'm awake, you know?"
“Sleep, those little slices of death — how I loathe them.”
Edgar Allan Poe
“Why can I never go back to bed? Who's is the voice ringing in my head? Where is the sense in these desperate dreams? Why should I wake when I'm half past dead?”
“Man is a genius when he is dreaming.”
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