5 Steps to a 5 AP Psychology, 2010-2011 Edition (28 page)

Consciousness
is your awareness of the outside world and yourself, including your own mental processes, thoughts, feelings, and perceptions. Your consciousness is selective, subjective and unique to you, always changing, and central to your sense of self.

This chapter examines variations in consciousness, some which you commonly experience and others which you don’t.

Key Ideas

Levels of consciousness

Sleep and dreaming

Sleep disorders

Hypnosis

Meditation

Psychoactive drugs—Depressants, Narcotics, Stimulants, Hallucinogens

Although your current level of consciousness is basically limited to what is relevant to you and what you notice, other events can either become conscious or influence your conscious experience. Your
preconscious
is the level of consciousness that is outside of awareness but contains feelings and memories that you can easily bring into conscious awareness. For example, if asked what you ate for dinner last night, you could easily remember and tell. Your
nonconscious
is the level of consciousness devoted to processes completely inaccessible to conscious awareness, such as blood flow, filtering of blood by kidneys, secretion of hormones, and lower level processing of sensations, such as detecting edges, estimating size and distance of objects, recognizing patterns, etc. For psychoanalysts, also known as
psychodynamic
psychologists, the
unconscious
, sometimes called the subconscious, is the level of consciousness that includes often unacceptable feelings, wishes, and thoughts not directly available to conscious awareness. According to cognitive psychologists, the unconscious is the level of consciousness that processes information of which you are unaware. The unconscious operates whenever you feel or act without being aware of what’s influencing you, whether it’s a stimulus from the current situation or from your past. Don’t confuse the unconscious and unconsciousness.
Unconsciousness
is characterized by loss of responsiveness to the environment resulting from disease, trauma, or anesthesia. Consciousness enables you to analyze, compare, and interpret experiences, and allows you to integrate what you already know, what you perceive in the present, and what you anticipate. Consciousness can be altered by sleep, hypnosis, meditation, and drugs.

Your finely tuned “biological clock,” controlled by the
hypothalamus
, systematically regulates changes in your body temperature, blood pressure, pulse, blood sugar levels, hormonal levels, and activity levels over the course of about a day. In an environment devoid of environmental cues to the length of a day, your free-running biological clock cycles approximately every 25 hours, but in a typical environment with light during the day and dark at night, cycles of changes,
circadian rhythms
, recur approximately every 24 hours. The forebrain,
reticular formation
, and thalamus are involved in the changes in wakefulness, arousal, and attention. Your physiological fluctuations are reflected in changes in your energy level, mood, performance, wakefulness, and sleep. Jet lag and night-shift work involve disruptions of circadian rhythms.

Why do you sleep? Evolutionary psychologists say that humans evolved a unique waking–sleeping cycle as a result of natural selection that maximized our chances of survival. Sleep serves at least two restorative functions—one involved in protein synthesis throughout the body, the other involved in maintaining
plasticity
of neural connections essential for storing and retrieving memories, which enables you to put together new material from the day before with old material. This is sometimes called consolidation. Sleep deprivation makes you drowsy, unable to concentrate, and impairs your memory and immune system. Sleep time seems to decrease from about 16 to 18 hours for a newborn, to about 7 to 8 hours for an adult.

Sleep
is a complex combination of states of consciousness, each with its own level of consciousness, awareness, responsiveness, and physiological arousal. The amount we sleep changes as we age.
Electroencephalograms (EEGs)
can be recorded with electrodes on the surface of the skull. EEGs have revealed that brain waves change in form systematically throughout the sleep cycle (see
Figure 9.1
). When you are awake, your EEG shows beta waves when you are alert and alpha waves when you are relaxed. As you fall asleep, you pass into a semiwakeful state of dreamlike awareness, known as the
hypnagogic
state; you feel relaxed, fail to respond to outside stimuli, and begin stage 1 sleep. EEGs of stage 1 sleep show theta waves, which are higher in amplitude and lower in frequency than alpha waves. As you pass into stage 2, your EEG shows high-frequency bursts of brain activity (called sleep spindles) and K complexes. As you fall more deeply asleep, your stage 3 sleep EEG shows some very high amplitude and very low-frequency delta waves. In stage 4, your deepest sleep stage, EEGs show mostly delta waves. During stage 4, your heart rate, respiration, temperature, and blood flow to your brain are reduced. You secrete growth hormone involved in maintaining your physiological functions. Stages 1 through 4, during which rapid eye movements do
not
occur, are called
NREM
or
Non-REM
sleep. After passing through stages 1 through 4, you pass back through stages 3, 2, and 1; then, rather than awaking, you begin
REM sleep (Rapid Eye Movement sleep)
about 90 minutes after falling asleep. Your eyes jerk rapidly in various directions; your breathing becomes more rapid, irregular, and shallow; your heart rate increases; your blood pressure rises; and your limb muscles become temporarily paralyzed. Because your EEG shows beta activity typical of wakefulness and theta activity typical of stage 1 sleep, but you are truly asleep, REM sleep is often also called paradoxical sleep. Throughout the night, you cycle through the sleep stages with REM sleep periods increasing in length and deep sleep decreasing. About 50% of our sleep is in stage 2. More of a newborn’s sleep is spent in REM sleep than an adult’s.
Nightmares
are frightening dreams that occur during REM sleep. Most of your dreaming takes place during REM sleep. Dreams remembered from other stages are less elaborate and emotional. Training in
lucid dreaming
, the ability to be aware of and direct one’s dreams, has been used to help people make recurrent nightmares less frightening.