Altered States of ConsciousnessWhat is consciousness? What are the different states of it? What does it mean to alter it?

Salvador Dali, The Persistence of Memory, 1931

Who sleeps?

What is sleep?

A period of inactivity with raised thresholds to arousal by external stimuli

The Electroencephalogram (EEG)

Measures electrical activity of groups of neurons across the scalp.

An event-related potential (ERP) in the temporal lobe caused by a simple auditory stimulus

Slow wave sleep (SWS)

Some characteristics of the sleep cycle

• The sleep/wake cycle is driven by a circadian rhythm (24 hour rhythm).

• The sleep cycle (or bout) is driven by an ultradian (less than 24 hour) rhythm. Your rest/activity activity has a 90 minute ultradian rhythm.

• The sleep cycle has a period of 90-120 minutes. This cycle may continue through wakefulness and may explain ‘day dreaming’.

• The sleep cycle changes with age. As we get older, we tend to have less REM sleep and more waking bouts through the cycle.

Why sleep?• Restoration theory

But … sleep deprivation does not interfere with physical capabilities and does not initiate a stress response

• Preservation and protection theoryAnimals that rely on vision tend to be diurnal (awake during

daylight) and those that rely more on other senses, and are prey to visual animals, tend to be nocturnal (awake

at night)

• Energy conservation

Rembrandt ‘Sleeping Woman’ (1654)

Why dream?• Real dreaming occurs during REM (rapid eye movement) Real dreaming occurs during REM (rapid eye movement)

sleep. Stage 2 ‘dreaming’ is characterized more as ‘sleep sleep. Stage 2 ‘dreaming’ is characterized more as ‘sleep thought’.thought’.

• REM sleep is also called ‘paradoxical sleep’ because the REM sleep is also called ‘paradoxical sleep’ because the EEG pattern can look very much like the awake, aware EEG pattern can look very much like the awake, aware EEG pattern.EEG pattern.

• Infants spend more time in REM sleep.Infants spend more time in REM sleep.• If awakened during REM sleep alertness and If awakened during REM sleep alertness and

attentiveness are high. Being awakened during slow attentiveness are high. Being awakened during slow wave sleep (Stage 4) drowsiness and confusion are high.wave sleep (Stage 4) drowsiness and confusion are high.

• REM sleep deprivation causes irritability, problems with REM sleep deprivation causes irritability, problems with procedural learning (consolidation) and REM rebound.procedural learning (consolidation) and REM rebound.

The American Academy of Sleep Medicine (AASM) offers the following tips on how to get a good night’s sleep:

•Follow a consistent bedtime routine.•Establish a relaxing setting at bedtime.•Get a full night’s sleep every night.•Avoid foods or drinks that contain caffeine, as well as any medicine that has a stimulant, prior to bedtime.•Do not bring your worries to bed with you.•Do not go to bed hungry, but don’t eat a big meal before bedtime either.•Avoid any rigorous exercise within six hours of your bedtime.•Make your bedroom quiet, dark and a little bit cool.•Get up at the same time every morning.