Chapter 5: Variations in Consciousness
1. Discuss the nature and evolution of consciousness.
Consciousness is the awareness of internal and external stimuli; it is a personal awareness. Freud argued that
people’s behavior and feelings were influenced by the unconscious needs, wishes, desires, and conflicts that lie
below the surface of the conscious awareness. The evolutionary basis of consciousness remains elusive.
2. Discuss the relationship between consciousness and EEG activity.
EEG is a device that monitors electrical activity in the brain over a period of time by means of recording
electrodes attached to the surface of the scalp. It measures brain wave activity, and there are four different types
of brain waves. All that is known for sure is that variations in consciousness are correlated with variations in brain
3. Summarize what is known about our biological clocks and their relationship to sleep.
Biological rhythms are period fluctuations in physiological functions. A circadian rhythm is a 24-hour biological
cycle found in humans and many other species that usually encompasses sleep and wakefulness. These rhythms
can leave individuals primed to fall asleep at a certain time of the day, and they tend to persist even when external
time cues are eliminated. Daily exposure to light readjusts people’s biological clocks. The SCN sends signals to
the pineal gland which secretes melatonin, a hormone that adjusts biological clocks and can induce sleepiness.
Generally, it’s easier to fly westward and lengthen the day than fly eastward and shorten it.
4. Discuss various methods of helping people to realign their circadian rhythms.
Rhythms can be realigned by giving people small doses of melatonin.
5. Describe how sleep research is conducted.
Sleep researchers monitor the physical and mental activity throughout the night. An EMG records muscle activity
and tension, and an EOG records eye movement. They also monitor heart rate, breathing, pulse, and body
6. Describe how the sleep cycle evolves through the night.
There are many factors that determine a person’s ability to fall asleep, including how long it has been since the
person slept, where the person is in his circadian cycle, the amount of noise or light in the room, the person’s age,
desire to fall asleep, recent caffeine intake, and stress level. Being awake first moves into a drowsy stage where
alpha waves are prominent. Stage 1 is a brief transitory stage of light sleep, giving way to lower-frequency theta
waves. Hypnic jerks are found in stage 1 sleep. Stages 2, 3, and 4 see decline in respiration rate, heart rate, muscle
tension, and body temperature. Sleep spindles are found in stage 2 sleep as the body is transitioning to slow-wave,
deep sleep. Slow-wave sleep consists of stages 3 and 4, during which high amplitude, low frequency delta waves
become prominent in EEG recordings.
7. Compare and contrast REM and NREM sleep.