Sleep and Fatigue Sleep is a behavioral state that is a natural part of every individual’s life. We spend about one-third of our lives asleep People generally know little about the importance of this essential activity. Sleep is a required activity and is important for normal motor and cognitive function.
Sleep is Needed Sleep actually appears to be required for survival. Rats deprived of sleep will die within two to three weeks, a time frame similar to death due to starvation. Rats deprived of REM sleep survive an average of only five months. In humans, extreme sleep deprivation can cause an apparent state of paranoia and hallucinations in otherwise healthy individuals.
Problem Sleepiness It is not normal for a person to be sleepy at times when he or she expects to be awake. Problem sleepiness may be associated with difficulty concentrating, memory lapses, loss of energy, fatigue, lethargy, and emotional instability. The prevalence of problem sleepiness is high and has serious consequences, such as drowsy driving or workplace accidents and errors. Lifestyle factors and undiagnosed or untreated sleep disorders can cause problem sleepiness.
Problems with Problem Sleepiness! Problem sleepiness can be deadly. Approximately 100,000 automobile crashes each year result from drivers who were “asleep at the wheel.” In addition to the high risk of automobile crashes, problem sleepiness can cause difficulties with learning, memory, thinking, and feelings. “ In time, sleep loss and workload pressure adversely interact with an individual’s circadian rhythm to reduce their reaction time, decrease vigilance and distort cognitive thinking and perceptual function.” LTC NICK PIANTANIDA TASK FORCE CENTAUR FLIGHT SURGEON
Shut down Misconception 1: Sleep is time for the body in general and the brain specifically to shut down for rest. Although there are some modest decreases in metabolic rate, there is no evidence that any major organ or regulatory system in the body shuts down during sleep. Brain activity continues while we are asleep
Less sleep is better Misconception 2: Getting just one hour less sleep per night than needed will not have any effect on daytime functioning. Even relatively modest daily reductions in sleep time (for example, one hour) can accumulate across days to cause a sleep debt. If the debt becomes too great, it can lead to problem sleepiness. Although the individual may not realize his or her sleepiness, the sleep debt can have powerful effects on daytime performance, thinking, and mood.
We adjust Misconception 3: The body adjusts quickly to different sleep schedules. The biological clock that times and controls a person’s sleep/wake cycle will attempt to function according to a normal day/night schedule even when that person tries to change it. Those who work night shifts naturally feel sleepy when nighttime comes.
Getting older Misconception 4: People need less sleep as they grow older. Older people don’t need less sleep, but they often get less sleep. That’s because the ability to sleep for long periods of time and to get into the deep, restful stages of sleep decreases with age.
A Good night’s sleep Misconception 5: A “good night’s sleep” can cure problems with excessive daytime sleepiness. Excessive daytime sleepiness can be associated with a sleep disorder or other medical condition. Sleep disorders, including sleep apnea (that is, absence of breathing during sleep), insomnia, and narcolepsy, may require behavioral, pharmacological, or even surgical intervention to relieve the symptoms. (70 correctable disorders identified)
Wasted Time Misconception 6: Sleep is wasted time not being productive. Sleep is not merely “down time” between episodes of being alive. Within an evolutionary framework, the simple fact that we spend about a third of our lives asleep suggests that sleep is more than a necessary evil. Much transpires while we are asleep, and the question is no longer whether sleep does something, but exactly what it does.
Why we need sleep
Sleep helps you to restore and rejuvenate many body functions:
Memory and learning – Sleep seems to organize memories, as well as help you to recover memories.
Mood enhancement and social behaviors - The parts of the brain that control emotions, decision-making, and social interactions slow down dramatically during sleep, allowing optimal performance when awake.
Nervous system – Some sleep experts suggest that neurons used during the day repair themselves during sleep.
Immune system – Without adequate sleep, the immune system becomes weak, and the body becomes more vulnerable to infection and disease.
Growth and development – Growth hormones are released during sleep, and sleep is vital to proper physical and mental development.
Our clock and hormones How we fall asleep Our bodies provoke us to sleep by sending messages from our circadian clocks – our inner time-keeping, temperature-fluctuating, enzyme-controlling devices. The circadian clock works in tandem with adenosine, a neurotransmitter that “turns down” many of the bodily processes that make us feel awake. Adenosine is created as our cells create the power needed to move us though the day. As the level of adenosine builds up in our brains, we feel sleepier. Along with corresponding messages from the circadian clock, this alerts us that its time to sleep.
Stages of sleep The Sleep Cycle: “ Relaxed wakefulness” (usually <10 minutes) Sleep is divided into two types: REM (Rapid Eye Movement) sleep and NREM (non-REM) sleep. REM sleep is when we dream. NREM sleep is further divided into four stages. (Drowsiness) Eyes move slowly under the eyelids, and muscle activity slows down. Easily awakened during Stage 1 sleep. (Light Sleep). In Stage 2, eye movements stop, heart rate slows, and body temperature decreases. (Light Sleep). In Stage 2, eye movements stop, heart rate slows, and body temperature decreases. During stages 3 and 4, you are difficult to awaken. REM sleep (Dream Sleep) - At about 70 to 90 minutes into your sleep cycle, you enter REM sleep. You usually have three to five REM episodes per night.
Deep vs Dream Sleep The importance of deep sleep and dream sleep Each stage of sleep offers benefits to the sleeper. Deep sleep is the most vital stage, as it is the first stage that the brain attempts to recover when we are sleep deprived. Deep sleep allows the brain to go on a little vacation needed to restore the energy we expend during our waking hours. Blood flow decreases to the brain in this stage, and redirects itself towards the muscles, restoring physical energy. Research also shows that immune functions increase during deep sleep. REM sleep, or dream sleep, is also very important. This stage is associated with processing emotions, retaining memories, and relieving stress. Our brains suspend logic, and we lose all self-awareness. This is why we dream. If our REM sleep is disrupted one night, our bodies don't follow the normal sleep cycle progression the next time we doze off. Instead, we often go through extended periods of REM until we "catch up" on this stage of sleep. But, if deep sleep has been lost as well, our brain attempts to catch up on this stage first – in fact, the brain will try and make up all of the deep sleep it has lost and only half of the REM sleep.
The “Night-cap” Misconception 7: Having a night-cap or drink helps you to sleep. Alcohol disturbs the body’s sleep cycle by preventing a person from entering the Rapid Eye Movement sleep stage. Without that REM sleep, while a person may have been in bed for eight hours, they awaken less able to think clearly. Col. John Campbell, Command Surgeon for the U.S. Army Combat Readiness/Safety Center.
Sleep Needs The recommendation that we need eight hours of sleep to function effectively during the day is not true for all. The amount of sleep that you need depends on a number of factors, including your genetic make-up; the amount of exercise you get; your daily activities; your age; and the quality of your sleep. A rule of thumb: If you wake up feeling refreshed, and you don’t feel sleepy during the day, you are getting enough sleep.