1. Sleep
Sleep is a form of consciousness, it is not a complete loss of consciousness, but rather a state of consciousness that is opposite to wakefulness.
(1) Stages of sleep.
In the awake state, the individual's brain waves are high-frequency and low-amplitude beta waves (14-30Hz), and during quiet times, the brain waves are alpha waves (8~13Hz). During the sleep process, the brain waves transition from high-frequency and low-amplitude to low-frequency and high-amplitude, and can be divided into five stages:
① Stage 1.
A. Brain wave changes: Mixed frequencies, both frequency and amplitude are low.
B. Duration: 10 minutes.
C. Main characteristics: In this stage, the individual is in a light sleep stage, the body relaxes, breathing slows down, and it is easy to be awakened by external stimuli.
② Stage 2.
A. Brain wave changes: Occasional sleep spindles (brief bursts of high-frequency and high-amplitude brain waves).
B. Duration: 20 minutes.
C. Main characteristics: It is difficult to wake the individual.
③ Stage 3.
A. Brain wave changes: Lower frequency, larger amplitude, appearance of delta waves, and sometimes sleep spindles.
B. Duration: 40 minutes.
C. Main characteristics: Muscles gradually become more relaxed.
④ Stage 4.
A. Brain wave changes: Continuous low-frequency and high-amplitude delta waves.
B. Main characteristics: Deep sleep stage, individual's muscles further relax, all body indicators slow down, and sometimes sleep talking, sleepwalking, bedwetting, etc. may occur.
Stages 3 and 4 of sleep are called "slow-wave sleep".
⑤ Rapid Eye Movement (REM) stage.
Appearance of high-frequency and low-amplitude brain waves similar to the awake state, eye movements, and dreams often occur during this stage.
(2) Regularity of sleep stages.
① In one night: The first four stages of sleep last a total of about 90 minutes, after which the individual enters the REM stage of sleep. The first REM stage only lasts 5-10 minutes, and the subsequent appearances become longer and the last one can last up to 1 hour. The third and fourth stages of sleep disappear at dawn.
② In a lifetime: Infants have very long periods of REM sleep, which gradually shorten with age. The amount of REM sleep in the elderly during sleep is very small.
(3) Functions of sleep.
① According to the restoration theory, sleep allows the body and brain to rest and recover their functions. However, experiments have shown that the duration of sleep can be shortened through training, and the key is to improve sleep quality and increase the proportion of deep sleep.
② From an ecological perspective, the ecological theory believes that sleep is to reduce energy consumption and avoid harm.
2. Dreams
Experiments on dream deprivation have shown that dreaming is a normal physiological and psychological phenomenon, and the deprivation of dreams can have adverse effects on psychological and physiological functions.
(1) Interpretation of dreams.
① Psychoanalytic perspective: Psychoanalysts such as Freud and Jung believe that dreams are manifestations of subconscious processes and are the most reliable way to access the subconscious.
In other words, dreams are repressed subconscious impulses or desires that appear in consciousness in a disguised form. These impulses and desires mainly reflect human sexual instincts and aggressive instincts. Dreams are actually a symbolic meaning for individuals and can be divided into manifest dreams and latent dreams. Manifest dreams are the content of dreams that can be recalled during recollection, while latent dreams are the meaning contained within manifest dreams. Freud also believes that dreams are not meaningless and chaotic, but represent the fulfillment of certain personal desires, that is, the demands and conflicts of subconscious desires, so they are meaningful and have unique value. The processing of dreams includes compression, displacement, symbolism, and secondary revision.
② Physiological perspective: Dreams are the subjective experience of random neural activity in the brain.
③ Cognitive psychology perspective: Dreams serve certain cognitive functions. During sleep, the cognitive system continues to retrieve, organize, integrate, and consolidate stored knowledge.
(2) Characteristics of dreams.
Research by Hobson and others suggests that dreams have cognitive uncertainty, dream content inconsistency and discontinuity, and mainly the discontinuity of dream content.