Psychology: Chapter Four

Paradoxical Sleep

Another term for REM sleep. This is due to the fact that the body can appear calm on the exterior, but other bodily systems and the brain are highly active, having many features that are similar to being awake.

Stage 3 NREM sleep.

A brief transitional stage that marks the start of deep sleep. The individual becomes less responsive to external stimly and more difficult to wake. When woken from stage 3 sleep, and individual is often left feeling groggy and disoriented. Delta waves become more common, replacing theta waves and sleep spindles, and they are occur 20-50% of the time. In this stage, the individual's eyes do not move, their muscles are relaxed, and heart and breathing rates continue to become slower and more regular.

Hypnogram

A graph that can plot the cycle of REM/NREM.

Rapid Eye Movement Sleep (REM)

A period of sleep when your eyes move rapidly, for short bursts of time. The first cycle of REM sleep lasts for approximately 10 minutes. It is a lighter sleep than stages 3 and 4, and therefore easier to be woken from. If an individual is woken during REm sleep, they often report that they were dreaming, which is true for everyone, even those who say they don't dream. The brain is very active suring REM sleep.

K-Complexes

A single sudden high amplitude wave. Occur about once a minute in Stage 2 NREM sleep, sometimes following the occurance of sleep spindles.

Infradian Rythms

Biological rhythms with cycles longer than 24 hours.

Ultradian Rythms

Biological rhythms with cycles shorter than 24 hours.

Circadian Rythms

Biological rythms with cycles that occur on a 24-hour cycle.

Stage 2 NREM Sleep.

Individuals spend approximately 20 minutes in Stage 2 NREM Sleep in their first NREM/REM sleep cycle, and are still easily awakon despite it being a deeper stage of sleep. Much like Stage 1, if woken an individual will feel that they haven't really slept at all. It is characterized by the presence of sleep spindles and K-complexes among theta waves. In this stage, the individual's eyes stop rolling, their muscles become further relaxed, and breathing and heart rate continues to decrease.

Stage 1 NREM sleep.

It is breif, lasting around 5 minutes for many people. A very light sleep that an individual can be easily woken from, and when an individual is, they may feel as though they haven't slept at all. In this stage of sleep, alpha waves are replaced with theta waves. In this stage, and individual's eye roll slowly, muscles relax and heart and breathing rate decreases.

Nightmares

Occur in REM sleep, and are more like to be rememberd than night terrors. They are more frequent in childhood but can be experience by adults, more commonly women than men. They are commonly unpleasent and upsetting dreams associated with feelings of helpless terror.

Theta Waves

Occurs during stage 1 NREM sleep, characterized by medium frequency brainwaves with mixed amplitudes.

Delta Waves

Occurs during stage 3 NREM sleep, characterized by a steady pattern of low frequency, high amplitude brainwaves.

Night terrors

Occurs in stages 3 and 4 NREM sleep, when voluntary muscles are very relaxed but still able to move. They are extremely frightening episodes where an individual wakes, at times screaming, in sheer terror. The individual is often sweating, with rapid heart and breathing rates, but has little or no recall of dreaming and often falls asleep again very quickly. These are not nightmares, and are often not remembered in the morning.

Beta Waves

Occurs when we are awake and alert, are short (low amplitude) and fast (high frequency)

Alpha Waves

Occurs when we are awake and drowsy, they are slow (lower frequency) and slightly bigger (high amplitude) than beta waves.

Cataplexy (Muscle Atonia)

Paralysis of the muscles that occurs during REM sleep, where the muscles that move voluntarily, especially those below the neck, are very relaxed to the point of being almost paralyzed.

Somnambulists

People who sleepwalk; occurs during NREM sleep. More common in childeren, with 7% experiencing sleep walking episodes, and 2% of adults.

Hypnogogic State

Said to be apart of Stage 1 NREM Sleep. It occurs when we enter a relaxed state, during which we experience hallucinatory images, flashes of light and vivid images. Involuntary muscle twitches that cause us to jolt are common within the stage.

Sleep Spindles

Short burst of rapid brainwave activity

Non-Rapid Eye Movement (NREM) sleep

Sleep stage characterized by little or none rapid eye movement, and is often divided into four stages that are determined by predominant brain wave patterns.

Rapid-Eye Movement (REM) sleep

Sleep stage characterized by rapid eye movements and increased dreaming.

Sawtooth Waves

Special type of Theta wave that resembles the blade of a saw.

Slow Wave Sleep

The collective name for Stages 3 and 4. They are grouped together like this due to their percentage of delta waves.

Stage 4 NREM sleep.

The deepest stage of sleep and is extermely to difficult to wake oan individual from. During this stage and individual's level of conscious awareness is very low, but can they can still be sensitive to certain stimuli. In teh first NREM/REM sleep cycle and indivdiual spends approximately 30 minutes in this stage, and it has been approximately and hour since they first feel asleep. Brainwave patterns consist of regular, slow and large delta waves for more than 50% of the time, and there is no eye moevemnt, little, if any, miscle activity, and heart and breathing rates are at their slowest and most regular during sleep.

Adaptive Theory

This aspect suggests that sleep depends on our need to find food, our vulnerability to predators, and it is meant to conserve energy.

Restorative (Restore and Recover) Theories of Sleep.

This theory states that sleep allows us to recharge our bodies, recover from the physical and psychological work during thee day and allows our bodies' growth process to function. According to this theory, sleep repairs and replenishes the body and prepares it for action the next day, enhances our mood, activates growth hormones, increases our immunity to disease, increases our alertness, and consolidates our memories. This theory has been critised due to thee fact that aspects of this theory are essentially 'useless' unless an individual is physically active during the day, and the assumption that the body rests during sleep, when parts of our bodies are working at rates they would when we are physically active.

Survival (Adaptive and Evolutionary) Theories of Sleep

This theory states that survival is the main purpose of sleep. Sleep is meant to be a means of increasing an animal's chances or survival within it's environment. This theory is criticized due to the fact that it does not explain why exactly we have to sleep, as all species sleep no matter the amount of food they eat or how in danger they are. At the same time, due to the fact that it assumes that sleeping is a way to safely hide from predators, as when sleeping an individual is more easily preyed upon.

Adaptive

To adjust in a useful or appropriate manner. Sleep can be this, as it allows us to change to meet the demands of our environment and it depends on how much food we need, how available it is, and our safety when we sleep.