¶ … Consciousness
The term consciousness has been defined as "mental awareness of sensations, perceptions, memories, and feelings" (Brown, et al. 2003, p. 166). Most human beings live in three states of consciousness: waking, sleeping, and dreaming. Two other states of consciousness, meditation and drug-altered consciousness, can be induced. This essay will explore these five states further and will conclude with a discussion on their psychological relevance.
Waking
Most of our lives are spent in waking consciousness, that is, a state of clear and organized alertness (Brown, et al., 2003). When we are awake, our perception of time, places, and events are real and often accurate. An electroencephalograph (EEG), a device that monitors the electrical activity of the brain, reveals that a person in the waking state has low-amplitude brain wave patterns that are fast and irregular.
Sleeping
Contrary to popular beliefs, sleep does involve some awareness (Lindsay et al., 2004). The problem is, the nature of this consciousness is difficult to study because people cannot give adequate reports of how they feel while sleeping. They are unresponsive. Thus, studies of sleep are based on peoples' self-reports of a sleep period after they have waken, and EEG recordings along with other physiological measures. An EEG is able to look at states of consciousness while sleeping based on how brain activity patterns change over time. Physiological measures record changes in the body while sleeping.
Sleep is composed of four stages and one pre-stage (Lindsay et al., 2004). The pre-stage occurs when an individual is lying in bed. They are relaxed with their eyes closed, yet they are not asleep. In this state, an EEG recording would show the fast and irregular wave patterns of the waking state be gradually replaced by slower, more synchronized alpha waves. In stage one sleep an EEG shows theta waves. Researchers know that this is the first stage of sleep because these wave patterns are lower in amplitude and slightly more irregular than those of a waking state. Nevertheless, most people who are woken up from this stage of sleep will likely report that they were not sleeping, but rather, their thoughts were simply drifting. Stage two sleep shows another change in EEG patterns. Sleep spindles and k complexes begin to interrupt the theta waves produced in stage one sleep. Sleep spindles are short burst of activity and k complexes are sudden sharp waveforms. This is a deeper sleep than stage one; however, the brain still shows some sensitivity to events in the external world. We know this because a loud noise presented to someone in stage two sleep shows up on an EEG as a k complex. Therefore, although the person sleeping is not consciously aware of the noise, the brain still reacts to it. Stage three sleep and stage four sleep produce delta activity on an EEG. These stages of sleep are sometimes referred to as slow-wave sleep because of the more synchronized and slow-wave brain patterns. In these stages a person is in a deep sleep and is difficult to wake up. If someone is shaken awake during slow-wave sleep they will be disoriented and it will take them a few minutes to reach a normal state of conscious awareness.
In addition to the changes in brain activity discussed above, physiological changes also occur throughout the four stages of sleep (Lindsay et al., 2004). Measures of arousal, such as breathing rate, heart rate, and blood pressure, consistently decline with each stage.
Dreaming
Approximately 70 to 90 minutes into the sleep cycle, abrupt changes appear in one's physiological patters (Lindsay et al., 2004). Heart rate rapidly increases and becomes more irregular; hand, feet, and face twitching occurs occasionally; a male's penis becomes effect and a woman's vagina become lubricated; and the eyes begin to move rapidly and irregularly behind closed eyelids. Furthermore, the EEG patterns lose their synchronicity, taking on low-amplitude, irregular patterns that resemble those of a waking state. This stage of sleep is referred to as REM (rapid eye movement) sleep, or paradoxical sleep. The term paradoxical sleep comes from the fact that a person is deeply...
Our semester plans gives you unlimited, unrestricted access to our entire library of resources —writing tools, guides, example essays, tutorials, class notes, and more.
Get Started Now