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.
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.
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.
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 asleep, yet the electrical activity in their brain resembles the patterns of a person who is awake. It would be difficult to wake someone up during REM; however, if shaken awake the person will appear instantly alert. Furthermore, well over 80% of people who are awaken from REM sleep will report an emotional and story-like dream. In fact, studies have found this to be true even among people who previously denied that they dream.
Meditation has been defined as, "a technique for self-induced manipulation of awareness, often used for relaxation and self-reflection" (Brannon & Feist, 2007, p. 208). In order to induce this sate of awareness, individuals will focus on achieving a passive state of mind by breath in a certain way and silently repeating a mantra (i.e. A sound, word, or string of words). Mediators report that such exercises create an expanded state of awareness, "characterised by a calm and pure form of thought unburdened by self-awareness" (Brannon, & Feist, 2007, p. 209). There are numerous forms of meditation and multiple ways of achieving the meditative state, most which can be traced back thousands of years to the practices of various Eastern religions.
In general, people meditate in order to temporarily stop the constant stream of mental activity in the brain and to allow the mind to become one with the universe (Brannon, & Feist, 2007). As well, meditation advocates claim that it has multiple benefits, including improved health, reduced stress, and spiritual insight and connection. In support of some of these claims, researchers have found that meditation reduces heart and respiratory rates, and regular meditation can reduce blood pressure. Furthermore, EEG recordings show significantly increased alpha waves during meditation. Nevertheless, researchers are still not clear on whether or not these physiological changes that accompany meditation constitute a separate state of consciousness, or if they simply indicate that the body is in a relaxed state. Some studies have found differences in the physiological changes of accomplished mediators and non-mediators in a relaxed state; however, the findings have been inconsistent.
Psychoactive drugs are defined as "drugs that affect behaviour and mental processes and produce alterations of conscious awareness" (Lindsay, 2004, p. 198). There are four categories of psychoactive drugs: depressants, stimulants, opiates, and hallucinogens. Each category of psychoactive drug impacts our conscious awareness in a different way.
Depressants affect our consciousness by slowing the activity of the central nervous system (Davison, 1994). Such drugs are often taken to produce feelings of pleasure and relaxation; however, higher doses can impair one's memory and concentration. Drugs in this category include alcohol and tranquilizers. Stimulants affect our consciousness by increasing the activity of the central nervous system. Such drugs tend to increase alertness, elevate mood, and produce physical changes such as increased heart rate and respiratory rates. Examples of stimulants include caffeine and cocaine. Opiates work by slowing the activity of the nervous system. They mimic the brain's own chemicals, specifically endorphins, which are involved in reducing pain. These drugs can reduce anxiety, elevate mood, and lower sensitivity to pain; however, people who take them are highly susceptible to physical and psychological dependency. Drugs in this category include opium and morphine. Hallucinogens, the final category of psychoactive drugs, are defined as "a class of drugs which tend to disrupt normal mental and emotional functioning and produce distorted perceptions" (Lindsay, et al., 2004, p. 202). In addition, some hallucinogens produce an effect known as synesthesia, which is a blending of sensory experiences (e.g. colors feel warm). LSD, one form of hallucinogen, is believed to mimic the action of the neurotransmitter serotonin. This drug acts on serotonin-based receptor sites in the brain, producing stimulation which causes the…