Final answer:
Sleep is an altered state of consciousness as evidenced by reduced sensory awareness and distinct brain wave patterns. Sensory awareness is markedly decreased in sleep, particularly during deep stages. The patterns of brain activity, as measured by EEG during sleep stages, differ significantly from wakefulness.
Step-by-step explanation:
The student asked to name and give examples of two different psychological characteristics of altered states of consciousness (ASC) that demonstrate that sleep is an ASC. There are several psychological characteristics that indicate sleep is indeed an ASC, including a reduced level of awareness of the environment and distinct patterns of brain activity.
Reduced Sensory Awareness
During sleep, especially in deeper stages such as slow-wave sleep, we experience a significant decrease in sensory awareness. For example, individuals are far less likely to respond to external stimuli like sounds or touch during deep sleep as compared to wakefulness. This reduced awareness is a clear indication that sleep is an altered state of consciousness.
Distinct Brain Activity Patterns
Brain wave patterns, observable through electroencephalography (EEG), change dramatically as a person transitions from wakefulness to sleep. For instance, the transition from wakefulness to the initial stages of sleep is marked by the appearance of alpha and theta waves, followed by sleep spindles and K-complexes in stage 2, leading to delta waves in the slow-wave stages (stages 3 and 4), and finally the unique brain activity of REM sleep. Since these brain wave patterns are distinct from those during wakefulness, they signify that sleep is an ASC.