Sleep is an underestimated entity in the aging process. Understanding the need for sleep as an age supporter there is a need to review the different phases and implications of it on health.
Details about sleep; http://www.agecontrol.nl/improve/tips-tricks/sort-out-sleep/
Brain activity is measured in waves lengths with each of them a specific name and function.
Beta waves are associated with day to day wakefulness. These waves are the highest in frequency and lowest in amplitude, and more dyssynchronous than other waves. That is, the waves are not consistent in their pattern. This desynchrony makes sense given the fact that day to day mental activity consists of many cognitive, sensory, and motor activities and experiences, and, thus, when awake, people are mentally dyssynchronous.
During periods of relaxation, while still awake, the brain waves become slower, increase in amplitude, and become more synchronous. These types of waves are called alpha waves. Such brain waves are often associated with states of relaxation and peacefulness during meditation and biofeedback.
Different stages in sleep ( details ; http://www.agecontrol.nl/psyche/sleep-next-1/
Sleep is divided into different phases. There are 4 stages and the REM sleep. All these stages progress in a cycle from stage 1-4 (also called NREM = Non-Rapid Eye Movement stage, divided in N1 – N4) and end with REM to start over again.
During stage 1 the sleep is lightly, and it is easy to wake up.
When entering stage 2 control slowly slips away and the sleep becomes deeper. Some people have a feeling of falling into a deep space, this phase takes around 50% of the sleep cycle.
Phase 3 and 4 takes around 30 % and the REM just 20%. Infants spend over 50% of REM sleep.
REM sleep. ( http://www.agecontrol.nl/psyche/sleeprem/)
REM = Rapid Eye Movement sleep. During REM, the eyes start moving fast and the brain activity is speeding up at different levels. When entering REM sleep, breathing becomes faster, irregular, and shallow, the eyes jerk rapidly in various directions, and the limb muscles become temporarily paralyzed. The heart rate increases, blood pressure rises, and males develop penile erections, females can have a more vaginal extraction. When people awaken during REM sleep, they often describe bizarre and illogical stories called dreams.
The first REM sleep period usually occurs about 70 minutes after falling asleep. A complete sleep cycle takes 90 to 110 minutes on average. The first sleep cycle each night contains a relatively short REM period and a long period of deep sleep (Phase 4). As the night progresses, REM sleep periods increase in length while deep sleep decreases. By morning, all time is spent in stages 1, 2, and REM.
A person awakened after sleeping just more than a few minutes is usually unable to recall the last minutes before falling asleep. This sleep-related form of amnesia is the reason people often forget phone calls or conversations from the middle of the night. It also explains why it is possible not to remember the alarms ringing in the morning if going back to sleep after turning it off. During the aging process, this event becomes more frequent and takes a long time for recuperation.
Since sleep and wakefulness are influenced by different neurotransmitter signals in the brain (serotonin and norepinephrine), foods and medicines that change the balance of these signals affect whether people feel alert or drowsy and how well they sleep. Caffeinated drinks such as coffee and drugs stimulate parts of the brain and can cause sleep disorder (even insomnia), or an inability to sleep.
Many antidepressants suppress REM sleep. Heavy smokers often sleep lightly and have reduced amounts of REM sleep. They tend to wake up after 3 or 4 hours of sleep due to nicotine withdrawal in the blood. Many people who suffer from sleep disorders try to solve the problem of alcohol – a so-called nightcap. While alcohol does help people fall into a light sleep, it also takes away their ability to enter REM and deeper, the more restorative stages of sleep. Instead, it keeps them in the lighter stages of sleep, from which they can be awakened easily. Alcoholics show a disoriented consciousness in the morning. Sleep deprivation is a strong aging promotor, the effects are clearly visible in physical and mental expression.
Everybody loses some of the ability to regulate the body temperature during REM, temperature changes in the environment can disrupt this stage of sleep. If REM sleep is disrupted one night, the body does not follow the normal sleep cycle progression the next time it dozes off. In different scientific sleep research projects, they discovered that instead of starting the new cycle, often people slip directly into REM sleep and go through extended periods of REM until finally “catch up” on the sleep cycle. Hereby the answer is “yes” to the question; can people catch up for lost sleep. But the answer is only “yes” when it happens coincidentally and not often.
The effects of REM sleep deprivation (RSD) on neurotrophic factors, specifically nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF), were assessed in 2000 by Sie et el. Neurotrophins are proteins found in the brain and periphery that aid in the survival, functioning, and generation of neurons; this is an important element in the synaptic plasticity process, the underlying neurochemical foundation in forming memories. BDNF protein has been shown to be necessary for procedural learning (a form of non-declarative memory). Since procedural learning has also exhibited consolidation and enhancement under REM sleep, it is proposed that the impairment of procedural learning tasks is due to the lack of BDNF proteins in the cerebellum and brainstem during RSD. In regard to NGF, the basal forebrain (production and distribution of AcH in the brain), more specifically the medial septal area, sends cholinergic (excitatory in the hippocampus) and GABAergic (inhibitory) neurotransmitters through fibers to the hippocampus target cells. These target cells then secrete NGF which plays a key role in the physiological state of the hippocampus and its functions. It has been noted that REM sleep increases the secretion of NGF, therefore it has been proposed that during RSD cholinergic activity decreases leading to a decrease in NGF and impairment in procedural learning.
REM sleep begins in response to signals sent to and from different regions of the brain. Signals are sent to the brain’s cerebral cortex, which is responsible for learning, thinking, and organizing information. Signals are also sent to the spinal cord to shut off the movement, creating a temporary inability to move the muscles (“paralysis”) in the arms and legs. Abnormal disruption of this temporary paralysis can cause people to move while they are dreaming.
REM sleep stimulates regions of the brain that are used for learning. Studies have shown that when people are deprived of REM sleep, they are not able to remember what they were taught before going to sleep. Lack of REM sleep has also been linked to certain health conditions, including migraines. This also refers directly to the aging process which accelerates with lack of sleep and even can exhaust a person completely cutting years of a healthy life.