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Why Do We Sleep?
Although a lot of research has been done, the question , “Why do we sleep?” is debated quite a bit in the scientific world. There are various different theories as to the reason we sleep and appear to need sleep(Klein). The Inactivity, Energy Conservation, Restorative, and Brain Plasticity Theories will be discussed on this page.
The main theories that have been adopted are:
Inactivity Theory- This theory has to do with evolution, adaptation, and natural selection ideals. The thought is that sleep was meant to initially keep organisms out of harm while most vulnerable, at night. Night time tends to be the time when predators go out to hunt. These predators have heightened senses of smell, sight, and hearing to pick up on any movement while it is dark. This means that animals that create a lot of movement will most likely be eaten. Sleep keeps them still and quiet, away from predators. Animals that did not sleep died off because they could not keep still and quiet during hunting hours. Sometimes this theory is also called the adaptive or evolutionary theory(“Why Do We Sleep, Anyway?” 2007).
However, would it not be a good idea to be conscious during a dangerous situation in order to react quickly? This counter argument brings up the idea that there does not seem to be an advantage of unconsciousness during a dangerous situation(“Why Do We Sleep, Anyway?”2007)
Energy Conservation Theory- The idea behind the Energy Conservation Theory is that sleep reduces an organism's demand of energy. When we sleep, our body temperature decreases to about one degree Celsius, which in turn decreases the amount of energy needed to regulate body temperature. Energy metabolism is also reduced during sleep, therefore, reducing the amount of energy an organism may need. This could explain why smaller animals with high metabolism need to sleep a lot longer than animals with low metabolism, and why cold blooded animals have less obvious sleep(Mastin 2013). Night time is also an inconvenient time to search for food for many animals, so sleeping can conserve their energy until morning when it is easier to see and find food(“Why Do We Sleep, Anyway” 2007).
The main theories that have been adopted are:
Inactivity Theory- This theory has to do with evolution, adaptation, and natural selection ideals. The thought is that sleep was meant to initially keep organisms out of harm while most vulnerable, at night. Night time tends to be the time when predators go out to hunt. These predators have heightened senses of smell, sight, and hearing to pick up on any movement while it is dark. This means that animals that create a lot of movement will most likely be eaten. Sleep keeps them still and quiet, away from predators. Animals that did not sleep died off because they could not keep still and quiet during hunting hours. Sometimes this theory is also called the adaptive or evolutionary theory(“Why Do We Sleep, Anyway?” 2007).
However, would it not be a good idea to be conscious during a dangerous situation in order to react quickly? This counter argument brings up the idea that there does not seem to be an advantage of unconsciousness during a dangerous situation(“Why Do We Sleep, Anyway?”2007)
Energy Conservation Theory- The idea behind the Energy Conservation Theory is that sleep reduces an organism's demand of energy. When we sleep, our body temperature decreases to about one degree Celsius, which in turn decreases the amount of energy needed to regulate body temperature. Energy metabolism is also reduced during sleep, therefore, reducing the amount of energy an organism may need. This could explain why smaller animals with high metabolism need to sleep a lot longer than animals with low metabolism, and why cold blooded animals have less obvious sleep(Mastin 2013). Night time is also an inconvenient time to search for food for many animals, so sleeping can conserve their energy until morning when it is easier to see and find food(“Why Do We Sleep, Anyway” 2007).
The preceding image shows the body temperature in degrees Fahrenheit on the left and Celsius on the right in relation to the hours of activity and work and hours of rest and sleep for humans(Mastin 2013). However, almost all humans are now in environments/communities in which just about any time is convenient or “okay” to get food. If we are now able to efficiently get food at any time, why is sleep still reserved for night time(Mastin 2013)?
Restorative Theory- According to this theory, sleep gives body the chance to rejuvenate. Muscle growth, repair of tissues, synthesis of proteins, and growth hormone release occur almost always, or in some bodily functions only occur while one is asleep("Sleep- Why Do We Sleep?"). While asleep, the body also produces about twice the amount of repair cells in the brain which could help with healing gray matter if an injury were to occur(“Why Do We Sleep, Anyway?” 2007).
Brain Plasticity Theory- The Brain Plasticity Theory states that sleep is related to changes in the organization of the brain. This would explain why sleep is very important for young children and babies- it can help them learn and remember. The brain is also not under a continuous stream of input as it is when we are awake. This leaves it time to “think”(“SLEEP RESEARCH”).
To watch a video to learn more about why we might need sleep, click here.
Sleep Disorders
Ethical Issues
Dr. William C. Dement
Home Page
References Cited
Restorative Theory- According to this theory, sleep gives body the chance to rejuvenate. Muscle growth, repair of tissues, synthesis of proteins, and growth hormone release occur almost always, or in some bodily functions only occur while one is asleep("Sleep- Why Do We Sleep?"). While asleep, the body also produces about twice the amount of repair cells in the brain which could help with healing gray matter if an injury were to occur(“Why Do We Sleep, Anyway?” 2007).
Brain Plasticity Theory- The Brain Plasticity Theory states that sleep is related to changes in the organization of the brain. This would explain why sleep is very important for young children and babies- it can help them learn and remember. The brain is also not under a continuous stream of input as it is when we are awake. This leaves it time to “think”(“SLEEP RESEARCH”).
To watch a video to learn more about why we might need sleep, click here.
Sleep Disorders
Ethical Issues
Dr. William C. Dement
Home Page
References Cited