Chapter 9Wakefulness and Sleep

Rhythms of Waking and Sleep

• Animals generate endogenous 24 hour cycles of wakefulness and sleep.

Rhythms of Waking and Sleep

• Endogenous circadian rhythms

Fig. 9-2, p. 267

Rhythms of Waking and Sleep

• Mechanisms of the circadian rhythms include the following:– The Suprachiasmatic nucleus.– Genes that produce certain proteins.– Melatonin levels.

Rhythms of Waking and Sleep

• Suprachiasmatic nucleus (SCN)

Fig. 9-4, p. 269

Rhythms of Waking and Sleep

• Two types of genes are responsible for generating the circadian rhythm.1. Period - produce proteins called Per.2. Timeless - produce proteins called Tim.

Fig. 9-5, p. 270

Rhythms of Waking and Sleep

• The SCN regulates waking and sleeping by controlling activity levels in other areas of the brain.

Stages of Sleep And Brain Mechanisms

• Sleep is a specialized state that serves a variety of important functions including:– conservation of energy.– repair and restoration.– learning and memory consolidation.

Stages of Sleep And Brain Mechanisms

• The electroencephalograph (EEG) allowed researchers to discover that there are various stages of sleep.

Stages of Sleep And Brain Mechanisms

• Alpha waves• Stage 1 sleep• Stage 2 sleep

– Sleep spindles – K-complexes

• Stage 3 and Stage 4• Non-REM (NREM)

Stages of Sleep And Brain Mechanisms

• Rapid eye movement sleep (REM)

Fig. 9-9, p. 276

Stages of Sleep And Brain Mechanisms

• Various brain mechanisms are associated with wakefulness and arousal.

• reticular formation• Pontomesencephalon• locus coeruleus• basal forebrain• Hypothalamus

– Orexin

Table 9-1, p. 280

Fig. 9-11, p. 279

Fig. 9-12, p. 280

Stages of Sleep And Brain Mechanisms

• During REM sleep: – Activity increases in the pons (triggers the

onset of REM sleep), limbic system, parietal cortex and temporal cortex.

– Activity decreases in the primary visual cortex, the motor cortex, and the dorsolateral prefrontal cortex.

Stages of Sleep And Brain Mechanisms

• Atonia

Sleep Disorders

• Insomnia

• Sleep apnea

• Narcolepsy– Cataplexy

• REM behavior disorder

Stages of Sleep And Brain Mechanisms

• Parasomnias– Night terrors– Sleep talking– Sleepwalking– Sleep eating– Sleep driving

Why Sleep? Why REM? Why Dreams?

• Conserve energy

• Restorative processes

Why Sleep? Why REM? Why Dreams?

• Enhancing learning and strengthening memory

Why Sleep? Why REM? Why Dreams?

• Humans spend one-third of their life asleep.

• One-fifth of sleep time is spent in REM.

Why Sleep? Why REM? Why Dreams?

• REM deprivation

• REM Rebound

• Research is inconclusive regarding the exact functions of REM.

Why Sleep? Why REM? Why Dreams?

• Accuracy of dreams…• Two biological theories of dreaming include:

1. The activation-synthesis hypothesis.

2. The clinico-anatomical hypothesis.