Consciousness is the awareness of the sensations, thoughts, and feelings being experienced at a given moment. Consciousness is divided into two broad states: waking and altered states of consciousness. In waking consciousness, we are awake and aware of our thoughts, emotions, and perceptions. When we enter an altered state of consciousness, our mental state differs from waking consciousness. Sleeping and dreaming our natural altered states of consciousness. Unnatural ones include hypnosis, and ones caused by drug use.


Sleep occurs in four different stages of sleep. Stage 1 sleep is the state of transition between wakefulness and sleep, characterized by relatively rapid, low-voltage brain waves. Stage 2 sleep is a sleep deeper than that of stage 1, characterized by a slower, more regular wave pattern, along with momentary interruptions of "sleep spindles". Stage 3 sleep is a sleep characterized by slow brain waves, with greater peaks and valleys in the wave pattern. Stage 4 sleep is the deepest stage of sleep, during which we are least responsive to outside stimulation. Several times a night, when sleepers are in stage 1 sleep, sleepers heart rate increases and becomes irregular, their blood pressure rises, their breathing rate increases, and males have erections. This is known as rapid eye movement sleep or REM sleep.


There are several theories that try to explain why we dream. There is the unconscious wish fulfillment theory, which is Sigmund Freud's theory that dreams represent unconscious wishes that dreamers wish to fulfill. According to Freud, the disguised or real meanings of dreams, hidden by more obvious subjects are known as latent content of dreams. The overt storyline of dreams is known as the manifest content of dreams. Today scientists don't really agree with Freud and his view. According to the dreams-for-survival theory, dreams permit information that is critical for our daily...