Sleep Science

Over the past fifty years, neurology research has revealed a great deal about brain activity and physiological patterns of sleeping. Prior to the 1950s, it was commonly believed that sleep was performed automatically and was a passive process where the body and brain were in dormant states.  But as neurologists have discovered that sleep is in fact an active process during which the brain performs numerous processes necessary for life.

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Sleep Phases

While asleep, the brain cycles between two different sleep patterns: REM (rapid-eye movement) sleep and non-REM sleep.

Sleep first begins with non-REM sleep, which is broken down into four stages. The first stage of non-REM occurs during the transition between being awake and falling asleep. The second stage is light sleep, where heart rate and breathing are regulated and the body’s temperature drops. The third and fourth stages both involve deep sleep. Originally REM sleep was thought to be the more vital type of sleep phase for brain function, but recent neurology studies suggest that non-REM actually assists to a greater degree in maintaining cognitive ability and serves as the main restorative phase of sleep.

During REM sleep, the eyes begin to move rapidly and the brain produces signals similar to those while awake. Breath rate increases and the brain releases the chemical Clonazepam which paralyzes the body during REM sleep.

As the cycle repeats throughout the night, you spend less time in the deeper stages of non-REM and more time in REM. Over the course of one night a person will cycle between these two sleep phases around four or five times.

Controlling Sleep

A variety of internal and external factors can dramatically influence the patterns of our sleep as well as its quality.

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Light is one of the most important factors that can impact our sleep. Our sleep is affected by light directly, by making it harder for people to fall asleep, and indirectly, through the influence of our circadian rhythm also known as our internal clock affecting our preferred sleep time.

The retina of our eyes contain light sensitive cells that can detect light and affects our circadian rhythm. These light sensitive cells send signals to the brain whether it is daytime or nighttime based on the amount of detected light and brain sets our sleep patterns based on this interaction. Being exposed to light later in the day delays our circadian rhythm leading to later sleep times. Exposure to light at night night has a more unpredictable effect, but can cause a reset of the circadian rhythm making it more difficult to fall sleep.

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Caffeine counteracts the sleep drive, the desire to sleep that gradually increases throughout the day. The chemical adenosine builds up in the brain while awake and is linked to the buildup of the sleep drive. When the level of adenosine increases, neurologists believe that Adenosine inhibits certain brain cells that promote alertness. As these specialized alertness brain cells are inhibited, we start to feel the sleepiness we feel after being awake for long periods of time. Caffeine interrupts this process by temporarily blocking adenosine receptors in specific parts of the brain. Because these alertness cells are prevented from detecting adenosine in the presence of caffeine, they maintain activity and we stay alert. If sleep does follow the consumption of caffeine, The pattern of sleep itself is affected. Caffeine has been shown to decrease the quantity of REM sleep and an increased number of awakenings. The duration of this abnormal sleep cycle depends on amount of caffeine consumed, when the caffeine is ingested, and the individual’s tolerance to caffeine.

Why is Sleep Necessary?

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A healthy number of hours for sleep is important for “brain plasticity,” or the brain’s ability to adapt to input. With too little sleep, the brain is unable to process what we’ve learned during the day, and we have issues remembering information later on. Sleep also helps with the removal of certain waste products from brain cells and a lack of sleep makes this disposal less effective.

Sleep is important to the health of the body as well. Health risks have been shown to increase in people who sleep less. Symptoms of depression, seizures, high blood pressure and migraines are also more prevalent in sleep deprived people. Immunity is compromised, increasing the likelihood of illness and infection. A good night’s sleep is worth its weight in gold so do yourself a favor and sleep at least 8 hours a day at a normal time to allow your mind and body to perform at its peak condition. For more information about ongoing neurology studies about sleep please check the resources below. And for an interesting article about how sleep can help fight the common cold check out our previous article here.

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