Sleep, Dreaming, and Circadian Rhythms

What are alpha waves?

Brief bursts f 8-12 Hz EEG waves. These waves are present just as you close your eyes in preparation for sleep.

What is stage 3 sleep?

Characterized by increasing delta waves.

What is initial stage 1 sleep?

Characterized by no striking changes in EOG or EMG.

What is sleep stage 2?

Characterized by sleep spindles and K complexes.

What is stage 4 sleep?

Mostly delta waves.

What is a sleep spindle?

A burst of oscillatory brain activity visible on an EEG that occurs during stage 2 sleep. It consists of 12-14 Hz waves that occur for at least 0.5 seconds. Sleep spindles are generated in the reticular nucleus of the thalamus.

What are the characteristics of REM sleep?

- Rapid eye movements - Loss of muscle tone - Low amplitude, high frequency EEG (similar to wakefulness) - Activity increases to waking levels in many brain structures - General increase in autonomic nervous system activity - Some degree of clitoral or penile erection

What are the common beliefs about dreaming?

1) External stimuli can become incorporated in dreams. 2) Dreams run on "real time" 3) People who claim that they do not dream report dreaming if awakened in REM 4) Sleeptalking and Sleepwaking (somnambulism), and enuresis (bedwetting) occur least frequently during REM sleep (core muscles are relaxed), and most frequently in Stage 4 sleep.

What are the 3 common tools used for sleep studies?

1. EEG (Electroencephalogram) 2. EOG (Electrooculogram) 3. EMG (Electromyogram)

What are theta waves.

3-7 Hz EEG waves that are present during initial sleep stage 1.

What is a K complex?

An electroencephalography (EEG) waveform that occurs during stage 2 of NREM sleep. It is the "largest event in healthy human EEG". They are more frequent in the first sleep cycles.

What is the difference between initial stage 1 sleep and emergent stage 1 sleep?

Initial Stage 1 EEG has no striking changes in EOG or EMG. Emergent Stage 1 EEG has Rapid Eye Movements (REM) and loss of muscle tone.

What is REM sleep?

Sleep associated with Emergent Stage 1 sleep.

What is NREM sleep?

Sleep associated with all stages other than emergent stage 1.

What is the progression through the sleep stages?

Sleep progresses from initial stage 1, stage 2, stage 3, stage 4, remains in stage 4 for some time, stage 3, stage 2, and then emergent stage 1. The remainder of the night is spent going back and forth through the various sleep stages.

What is sleep stage 1? What brain waves are associated with initial sleep stage 1?

Sleep stage 1 is characterized by a slight slower signal than wakefulness. Theta waves.

What is slow-wave sleep?

Stage 3 and Stage 4 sleep, collectively.

What is hypnagogia?

The experience of the transitional state from wakefulness to sleep. The hypnagogic state of consciousness, during the onset of sleep.

What are delta waves?

The largest and slowest EEG waves at 0-3 Hz.