Sleep and Dreaming

inherent timing mechanism that controls various biological processes- endogenous- comes from within

animals near poles are more affected by seasonal changes

• neural system that times behavior
• allows animals to anticipate events before they happen 
• ex. birds head south for winter

• (no not the monthly one)
• time required to complete a cycle of activity

• yearly
• ex. migratory cycles of birds

• less than a year
• human menstrual cycle (there it is!)

• daily cycle
• (sleep)

• Less than a day
• (eating, pooping) 

• body's own rhythm when there are no external cues
• ex. if dim lighting/can't tell whether it's night or day than you will naturally develop a sleep cycle

• 25-27 hour cycle
• sleep-wake cycle shifts an hour per day

• Environmental event that entrains biological rhythms
• Ex. "time giver"

Determination or modification of the period of a biorhythm.

fatigue and disorientatior from rapid travel through time zones due to exposure to a changed light-dark cycle

Main pacemaker of circadian rhythms located just above the optic chiasm

• Neural route from a subset of cone receptors in the retinal to suprachiasmatic nucleus of the hypothalmus
• allows light to entrain the rhythmic activity of the SCN

• hormone secreted by the pineal gland during the dark phase of the day-night cycle
• influences daily and seasonal biorhythms

In winter: melatonin levels decrease, gonads shrink, testosterone levels decrease, and sexual behavior decreases.

In summer: melatonin levels increase, gonads grow, testosterone levels increase, and sexual behavior increases.

Record of brain-wave activity

Record of muscle activity

Record of eye movements 

Fast brain-wave activity (15-30 Hz) pattern associated with a waking EEG

Large, extremely regular brain waves (7-11 Hz) associated with drowsiness

Slow brain-wave activity (1-3 Hz) pattern associated with deep sleep (NREM sleep)

Fast brain-wave pattern displayed by the neocortical EEG record during sleep

• no tone
• complete muscle inactivity produced by the inhibitation of motor neurons

• cortex is bombarded with signals from brainstem and produces the pattern of waking EEG
• cortex generates images, actions and emotions from personal memory stores 
• dreams are personal but have no meaning

• amygdala
• visual association areas
• motor cortex
• brain stem

• Cholinergic nucleus in the dorsal brainstem has a role in REM sleep behavior
• projects to the medial pontine reticulum

initiates REM sleep

• nucleus in the pons participating in REM sleep
• ex. produces the atonia of REM sleep

• dreams are organized and biased toward threatening images
• dreams are biologically important-lead to enhanced performance in dealing with threatening life events (adaptive function) 

Brief period of sleep lasting a second or so 

Subjects spend more time in REM sleep in the first available sleep session 

Sleep plays a role in solidifying and organizing events in memory

• large reticulum- mix of cell and nuclei and nerve fibers- that runs through the center of the brainstem
• associated with sleep-wake behavior and behavioral arousal
• Stimulation of the RAS produces a waking EEG
• Damage to it produces a slow-wave EEG