3 measures of sleep
EEG, EOG, EMG
EEG
electroencephalogram (brain waves)
EOG
electrooculogram (records eye movement)
EMG
electromyogram (records loss of activity in neck)
3 Stages of Sleep (EEG)
- Waking EEG but slower
- K complexes and sleep spindles
- delta waves (large and slow)
Alpha waves
more alpha = more relaxed
Interpretations of Sleep
- dreams run on real-time
- everyone dreams
- external stimuli may be incorporated into dreams (muscle activity can’t move much)
4 stages of sleep
Awake
1. near awake
2. light sleep
3. deep sleep
4. deep sleep (REM)
Freud’s explanation of dream
Manifest content: stuff people dream of
Latent content: has to be interpreted
Activation Synthesis Theory
brain is going through repair cycles
Recuperation Theory
wakefulness disrupts homeostasis- sleep restores homeostasis
- all things sleep
REM sleep deprivation
sleep deprivation increases the efficiency of sleep
Circadian Sleep-Wake cycles
“about a day”
- zeitgebers: environmental cycles that entertain circadian cycles (light-day)
Free running circadian sleep- wake cycles
a rare sleep pattern whereby the sleep schedule of a person shifts later every day.
Circadian Clock
in the Suprachaismatic Nuclei
adaption theory
sleep caused by an internal timing mechanism
sleep evolved to protect us
Neural Mechanisms of entrainment
- cutting optic nerve before the optic chiasm (clock doesn’t work because you can’t see light)
- cutting after optic chiasm (clock still works)
The suprachiasmatic nucleus (SCNs)
lesions do not reduce sleep time
Two Areas of the Hypothalamus Involved in Sleep
ventrolateral and median preoptic areas
Reticular Formation and Sleep
facilitating not only wakefulness but REM sleep as well
Reticular REM-Sleep Nuclei
The raphe nuclei, a thin cluster of serotonin-releasing nuclei that lie along the
midline of the caudal reticular formation; lesions here produce insomnia.
The basal forebrain, including the anterior hypothalamus; lesions here reduce sleep
duration.
The caudal reticular formation REM-sleep circuits; various sites in the brainstem
control different aspects of REM sleep.
Drugs that affect sleep
- Hypnotic drugs
- Antihypnotic drugs
- Melatonin
