Introduction
Sleeping has been an important aspect of our daily lives and a vital to our overall well-being. We spend up to one-third of our lives asleep. The overall state of our sleep health remains essential throughout our life time.
Unlike in the 1950s when most people thought of sleep as a passive, dormant part our lives, now we are fully aware that our brains are very active while we are asleep and sleep affects the way we function physically and mentally in many ways.
Sleep is quite important to a number of brain functions which includes how nerve cells communicate with each other. Recent findings suggest that sleep plays a major role in removing toxins in the brain that builds up while we are awake. The ability to sleep and to stay awake are influenced by signals generated by many neurotransmitters in the brain, the kind of foods we eat and medication taken also influences the balance of these signals and affects whether we feel alert or drowsy, how much sleep we get and also how deep we sleep. Caffeinated drinks like coffee, diet pills and decongestants also stimulate some part of the brain and can cause insomnia. Heavy smokers tend to sleep very lightly and wake up after just about 3 or 4 hours of sleep due to nicotine withdrawal.
When a person is in coma or under anesthesia they are often said to be asleep, although people in these conditions cannot be awakened and their brains do not produce the active complex wave patterns seen in normal sleep. Instead, they produce very weak and slow brain waves, sometimes not even detectable.
Having enough sleep directly affects the mental and physical quality of our waking life just as not having enough sleep can take a serious toll on your daytime energy, emotional balance, productivity and even weight. Even though we most people are aware of the importance of sleep they usually loose their sleep over work and sometimes things that are not even important, I don't think anything is worth loosing a sleep for. Some people try to sleep at night knowing it's importance yet they just toss and turn all night long. This problem can be solved by making changes to our daytime routine and bedtime habits as they could have great impact on how well we sleep at night.
Brain Basics: The Anatomy of Sleep
Let's briefly look at some structures in the brain that are involved with sleep.
The Hypothalamus
This is a small structure quite deep inside the brain containing different groups of nerve cells that act as control centers and affects sleep and arousal. Also within the hypothalamus is the siprachiasmatic nucleus (SCN) which is a cluster of thousands of cells receiving information about light exposure directly from the eyes, and it controls our behavioral rhythm with this information.
The Thalamus
This part of the brain relays information to the cerebral cortex (a brain covering that interprets and processes information from short to long-term memory). There are various stages of sleep and in most of those stages the thalamus is usually quiet, this is to allow us disconnect from the outer world.
The Brain Stem
This is at the base if the brain, it communicates with the hypothalamus and together they control transition between wake and sleep. The brain stem and the hypothalamus contains some sleep promoting cells which produces a chemical in the brain called GABA which reduces activities in the arousal centers of the brain stem and hypothalamus. The brain stem consists of the pon, medulla and mid brain and they play a major role in REM sleep (rapid eye movement) especially the pon and medulla. They send signals to relax muscles that are essential for body postures and limb movements, this is to prevent us from acting out our dreams.
The Pineal Gland
Located within the brain's two hemisphere, it recieves information from SCN and increases the production of melatonin, this is a hormone which helps put us to sleep when the light is down.
The Basal Forebrain
Close the front and bottom of the brain, it promotes the ability to sleep and wakefulness, while part of the mid brain functions as an arousal system
The Amygdala
The amygdala is one of two almond-shaped groups of nuclei located deep and medially within the temporal lobes of the brain in complex vertebrates, including humans. It was shown in research to perform a primary role in the processing of memory , decision-making, and emotional responses, they become increasingly active during REM sleep.
REM (rapid eye movement) Sleep
Rapid eye movement sleep is the stage of sleep characterised by rapid side to side movement of the eyes behind closed eyelids.
During this stage, the activity of the brain's neurons is quite similar to that during waking hours, breathing becomes faster and irregular, heart rate and blood pressure increases to near waking levels, males develop penile erections.
Most of the vividly recalled dreams occur during REM sleep. It is the lightest form of sleep, and people awakened during REM usually feel alert and refreshed.
The first REM sleep period usually occurs within the first 90 minutes after we fall asleep. It takes up to 90 to 110 minutes on average to make a complete sleep cycle. Usually the first sleep cycles every night contains relatively short REM sleep periods and long periods of deep sleep. As night progresses, we experience increased REM sleep periods while deep sleep decreases.
At the beginning of of REM sleep, signals are sent from the pons to the thalamus, which sends the signal to cerebral cortex which is the outer layer of the brain that is responsible for learning, thinking, and organizing information. Signal is also sent by the pons to shut of neurons in the spinal cord, causing temporary paralysis of the limb muscles. If there is an interference with this paralysis people will begin to act out their dreams physically. That is why you could see a person dreaming about his involvement in fight physically trying to throw punches and probably kicks the person sleeping next to him.
REM sleep is very important for brain development during infancy as it stimulates the region of the brain responsible for learning this explains why children or infants spend more time in REM sleep than adults. After learning if deprived of REM sleep recalling might be difficult.
The Circadian Rythms
Ever wondered how your body know to feel energized and drowsy around the same time every day? Well that's your circadian rhythm at work.
Your circadian rhythm is basically a 24-hour internal clock running within your brain which cycles between sleeplessness and alertness at regular intervals. It is also known as sleep wake cycle. Although the circadian rhythms are built-in they can be adjusted to the local environment by external cues called Zeitgebers which includes light, temperature and redox cycles.
The circadian rhythm is controlled within the brain by a part of the hypothalamus, as I mentioned earlier external factors like light and darkness also have impact such that when it's dark at night the eyes sends signals to the hypothalamus that it might be time to feel tired and hypothalamus sends a signal to the body to release melatonin, which makes the body tired, this explains why the circadian rhythm tends to be in sync with the cycle of day and night time.
The circadian rhythm works best when a regular sleep habit is adopted.
Growing up I attended a boarding school for the most part of my secondary education and usually for those that attended boarding school 10pm Nigerian time is lights out and everybody must be on their bed at that time, its a must as long as you are a junior student and as early as 5am everybody must be awake. I got used to the cycle and my circadian rhythm was adjusted to follow that cycle. When I was on holidays with no senior prefects coming to hit the dormitory gate for us to wake up by 5am I noticed that on my own I usually wake up by 5am even after I was with done with secondary school it took some time before I stopped waking up by 5am and that was because then I usually go back to bed when ever I wake that early so my circadian rhythm readjusted.
Circadian rhythm in individuals varies ranging between 23.5 and 24.5 hours depending on variations in the person's PER or period gene with an average of 24.2 hours just slight more than earth's rotation.
Scientists discovered that by depriving people of light and other external cues, their biological clock works on a 25-hour cycle.
How Much Sleep Do We Really Need
| Age group | Sleep range |
|---|---|
| Newborns (0-3 months ) | 14-17 hours each day |
| Infants (4-11 months) | 12-15 hours |
| Toddlers (1-2 years) | 11-14 hours |
| Preschoolers (3-5 years) | 10-13 hours |
| School age children (6-13) | 9-11 hours |
| Teenagers (14-17) | 8-10 hours |
| Younger adults (18-25) | 7-9 hours |
| Adults (26-64) | 7-9 hours |
| Older adults (65+) | 7-8 hours |
Most of us have come to terms with the fact that a good night sleep is of great importance and tends to impact our performance in our daily activities, but still, just a few of us have been able to make a it a priority to have good night sleep.
Some people might have even forgotten what it feels like to be well rested because they have accumulated a lot of sleep debts. yes! sleep debts.
What is sleep debt? in just a few words, while you are awake a chemical called adenosine builds up in your blood, and when you sleep, your body breaks it down.
This means that when you don't get enough sleep as you should according to the table above your body wouldn't have properly broken down the adenosine in your bloodstream and so long as you are awake adenosine continues to build up upon the unbroken ones in your blood stream.
The adenosine build up in your blood would make you more desperate to snooze and would slow down your reaction making you prone to mistakes that could be avoided and also cause you to under perform in your daily activities.
The amount of sleep each person needs depends on many factors, including age.
Women in the first 3 months of pregnancy often need several more hours of sleep than usual.
The amount of sleep a person requires is also dependent on how much sleep deprivation he or she have had, this is where sleep debt comes to play as we have mentioned above, because eventually the body would require that debt be repaid. We don't adapt to getting less sleep than we need, though we might get used to a sleep-deprivation schedule, it would definitely affect our judgment and impair our performance.
If you feel sleepy during the day, even while carrying out a very boring task, you haven't had enough sleep, Do you fall asleep within 5 minutes of lying down? you probably have severe sleep deprivation or even a sleep disorder.
Older people tend to get shorter sleep time although they still require the same amount of sleep as they did in their adulthood. Most elderly people above age 65 experience sleeping disorder like insomnia, and very short deep sleep. Changes like this might be as a result medical problems common among the elderly and from medications or may also be a normal part of aging.
Benefits Of Having Enough Sleep
Sleep is very necessary for our nervous system to function properly. Sleep gives neurons used while we are awake a chance to shut down and repair themselves.
Without adequate sleep neurons may get so polluted with byproducts of normal cellular activities that they begin to malfunction. sleep gives inactive neurons the chance to make some important neuronal connection that may not function properly due to inactivity.
In children and young adults growth hormones are released during deep sleep, there is increased production of most body cells and reduced breakdown of proteins.
Brain activities that control emotions, decision-making processes, and social interactions is drastically reduced during deep sleep, this is to ensure optimal emotional and social performance during wake times.
Having enough sleep improves memory, while you're asleep skills learned at wake times are improved in a process called consolidation.
Consolidation basically means moving memories from a short term buffer-like memory to a long term memory and updating believes and general knowledge with new learnings.
In addition to consolidating memories, or making them stronger, your brain appears to recognize and restructure them, which may result in more creativity. Take for instance you are learning a new programming language, and lets say you've learnt to some extent and practiced. When you sleep consolidation takes place and you'll perform better when you wake.
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Sources
How much sleep we really need
Sleep debt
What is sleep
Benefits of sleep
How to sleep better