This is my second round of research for my inquiry question: “what does it mean to be conscious?” I’ll be looking into sleeping and dreaming and how it relates to consciousness. Evidently, when we fall asleep, we don’t fall asleep all at once. Some nights, we lay in bed and will ourselves to drift off. Sometimes, our minds refuse to shut down: the longer we can’t sleep, the more we worry about it and the worst it gets. Even so, at one point, we drift off and we don’t realize that we fell asleep. Thus, as you can see, the ways we lose consciousness isn’t as simple as being awake in one second and being unconscious the next. Consciousness is, thus, transitionary. In other words, there isn’t a light switch for it. We can’t simply be conscious and unconscious whenever we want to. For this research round I’ll be looking into the reasons to why we need and fall asleep, the stages of sleep and what circadian rhythms + dreams are:
Why do we need sleep?
-Sleep is an active period where much processing, restoration, and strengthening of the mind and body occurs (1).
-->helps us feel more alert, more energetic and happier (2).
-It helps us solidify and strengthen our memories. Our brains face an incredible amount of information every single day. We need to take in all of that by processing and storing it. These steps occur mostly when we are asleep. Consolidation is when our recollections go from short-term to a longer-term memory. We also need sleep to restore, rejuvenate, grow muscle, repair tissues and synthesize hormones for our body.
-Children need more sleep than adults as they learn language, social and motor skills at an incredibly fast pace throughout their development.
This photo shows the amount of sleep that each individual need:
Newborns (0 to 3 months): 14 to 17 hours each day
Infants (4 to 11 months): 12 to 15 hours
Toddlers (1 to 2 years): 11 to 14 hours
Preschoolers (3 to 5 years): 10 to 13 hours
School-age children (6 to 13 years): 9 to 11 hours
Teenagers (14 to 17 years): 8 to 10 hours
Adults (18 to 64 years): 7 to 9 hours
Older adults (over 65 years): 7 to 8 hours (1).
-There are also some interesting theories to why we need sleep:
-->Inactivity Theory: is also known as the adaptive or evolutionary theory. This theory suggests that inactivity at night is an adaptation that organisms achieved to keep them out of harm’s way when they would be more vulnerable than during daylight hours. It is believed that animals that were able to stay still and quiet during these periods of vulnerability had an advantage because of reasons such as they would attract less predators.
-->Energy Conservation Theory: natural selection is competition for and effective utilization of energy resources. It is thought that if an organism is able to reduce their energy during times it is least efficient to search for food, they would have more during when they are hunting.
-->Restorative Theories: is a theory that organisms need to restore what is lost in their body while they are awake (2). Sleep provides an opportunity for the body to repair and rejuvenate itself. Restorative functions such as muscle growth, tissue repair, protein synthesis, and growth hormones are released and occurring mostly during sleep (1, 2). It is found that animals that are sleep deprived lose all immune function and die in just a matter of weeks.
-->Brain Plasticity Theory: organisms need sleep to correlate changes in the structure and organization of their brain (2).
-If we don’t have enough sleep to feel awake and alert, it results in mental, emotional, and physical fatigue. This is called sleep deprivation (3). It is linked to:
-->higher rates of motor vehicle accidents, BMI, increased risk of obesity, diabetes, heart problems, depression and substance abuse.
-->decreased attention and focus on environmental sensory input, slower reaction times and problems to remember new information (3, 4).
-->children and young adults are the most vulnerable
-->may be a symptom of an undiagnosed sleep disorder or other medical problem
-->accumulates sleep debt (3).
How do we fall asleep? What are the stages of sleep? What happens in our brain when we fall asleep/unconscious?
-there are stages to when we fall asleep. They are...
-->Stage 1 (NREM). This is where brain waves slow down which becomes to a form called theta-band activity. Here brief bursts of “alpha activity” occur (5). In other words, the states of consciousness fluidly run into each other and are often are not recognized by the individual itself. An individual can remember bits and pieces of things, but not much. Slow, even breathing, regular heartbeat and lowered brain temperature are the characteristics (4). A study at a Henry Ford Hospital study had put people into stage 1 sleep for 10 minutes. When it was over, most individuals believed they were awake the whole time. However, they were not. Many were snoring (6)!
-->Stage 2 (NREM): This is when muscular activity decreases, and conscious awareness of the external environment disappears (4). The short bursts of alpha activity decrease (5). High-amplitude brain waves, short periods of increased activity, heightened sensitivity to sound stimuli, slowed bodily functions are the characteristics for stage 2.
-->Stage 3 (NREM): This happens about 30 to 45 minutes into someone’s sleep. Slow brain waves, deep sleep and disorientation and grogginess if awaken are the characteristics of this stage.
-->Stage 4 (REM): REM stands for rapid eye movement sleep. In this stage, most muscles are paralyzed. It’s harder to arouse the sleeper during this stage, compared to any others. Most of a person’s dreaming occurs here (7).
**Sleep progresses from stage 1 to stage 2 to stage 3, and then back to stage 2 before going into the REM phase. Once the REM phase is over, stage 2 repeats. When a person sleeps, he or she will go through this entire cycle about four or five times if they have a full night of sleep (4).**
Why and how do we dream?
-Dreams occur due to chemical and electrical signals passing from neuron to neuron along connected pathways. These connections change as you think, learn and dream. At night, the brain rewires this network to make it more efficient. That is, it erases unimportant short-term memories and replays experiences with strong emotional tags (7).
-However, some scientists believe dreaming has no function (7, 8). They think it is an “epiphenomenon” that is the mental activity that occurs during REM sleep.
-Others believe that we simply move from focused waking to looser waking thoughts when we sleep. That is, mental activity gets less focused, looser and more imagistic. It is thought as the state where individuals make connections most loosely (8).
*Fact: You dream about what you see when you're awake. In an experiment, they had volunteers wear googles with red lenses for a few days without taking them off. Within these days, all the objects in their dreams was perceived as the colour red (7).*
What are circadian rhythms?
-Changes that effect people physically, mentally and behaviorally. However, it also influences bodily functions such as sleep-wake cycles. The body’s “master clock” controls the production of melatonin, a hormone that makes you sleepy.
-It follows an approximate 24-hour cycle.
-It responds primarily to light and darkness in an organism’s environment.
-Thus, it regulates duration of sleepiness and wakefulness throughout our day as well as when we sleep.
-Found in most living things (4, 9).
For my next post, I'll be
Thank you for reading! Please feel free to leave any comments or suggestions for my next round of research. I'll leave you with a question: why do you think we have dreams?