Sweet slumber! Sleep is something we all do. More importantly, sleep is something we all need for vibrant health. Listen in this week as we discuss theories of sleep, stages of sleep, and the science of why we sleep. You’ll want to listen to the end! We wrap up by giving you 10 Tips for Improving Your Sleep Hygiene.
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Notes on Sleep
Different levels of sleep are different for different people. It’s recommended that you get 7-8 hours of sleep a night. Sleep is really important physiologically, and the biologically, it’s a necessity in our body. You cannot get your sleep back. You cannot correct for missing sleep.
Theories on Sleep
Inactivity Theory One of the earliest theories of sleep, sometimes called the adaptive or evolutionary theory. Suggests inactivity at night is an adaptation that served a survival function by keeping organisms out of harm’s way at times when they would be particularly vulnerable. Energy Conservation Theory Research has shown that energy metabolism is significantly reduced during sleep by as much as 10 percent in humans, and even more in other species. For example, both body temperature and caloric demand decrease during sleep, as compared to wakefulness. Many scientists consider this theory to be related to and part of the inactivity theory. Restorative Theory Sleep provides an opportunity for the body to repair and rejuvenate itself. Science shows animals deprived entirely of sleep lose all immune function and die in just a matter of weeks. This is further supported by findings that many of the major restorative functions in the body, like muscle growth, tissue repair, protein synthesis, and growth hormone release, occur mostly, or in some cases, only during sleep. Other rejuvenating aspects of sleep are specific to the brain and cognitive function. For example, while we are awake, neurons in the brain produce adenosine, a byproduct of the cell’s activities. The buildup of adenosine in the brain is thought to be one factor that leads to our perception of being tired. Scientists think that this buildup of adenosine during wakefulness may promote the drive to sleep. As long as we are awake, adenosine accumulates and remains high. During sleep, the body has a chance to clear adenosine from the system, and as a result, we feel more alert when we’re awake. Brain Plasticity Theory One of the most recent and compelling explanations for why we sleep is based on findings that sleep is correlated to changes in the structure and organization of the brain. This phenomenon, known as brain plasticity, is not entirely understood, but its connection to sleep has several critical implications. It’s becoming clear, for example, that sleep plays a critical role in brain development in infants and young children. Infants spend about 13-14 hours per day sleeping, and about half of that time is spent in REM sleep, the stage in which most dreams occur. A link between sleep and brain plasticity is becoming clear in adults as well. This is seen in the effect that sleep and sleep deprivation have on people’s ability to learn and perform a variety of tasks.
Stages of Sleep
Stage 1 – Non-REM sleep. The changeover from wakefulness to sleep. During this short period of relatively light sleep, your heartbeat, breathing, and eye movements slow, and your muscles relax, with occasional twitches. Stage 2 – Non-REM sleep. A period of light sleep before you enter deep sleep. Your heartbeat and breathing slow, and muscles relax even further. Your body temperature drops, and eye movement stops. Stage 3 – Non-REM sleep. The period of deep sleep that you need to feel refreshed in the morning. It occurs in longer periods during the first half of the night. Your heartbeat and breathing slow to their lowest levels during sleep. Your muscles are relaxed, and it may be diffi