2.  EEGs  Monitor brain waves  Wake people up in the midst of a sleep cycle or dream  Eugene Aserinsky – discovered REM sleep › Works with Nathaniel Kleitman  William Dement – Father of sleep medicine; World’s first sleep laboratory

4.  Circadian Rhythms (about a day) › Body rhythms that occur on a 24 hour cycle › Biological clock › Sleep-Awake cycle  Ultradian Rhythms › Occur more than once a day › Sleep stages

5.  Suprachiasmatic Nucleus (SCN) › Cluster of neurons in the hypothalamus › Receives info about day and night cycles from the retina › Depending on cycles detected by eye, it releases neurotransmitters that control body temperature, metabolism, blood pressure, hormone levels, hunger › Works with pineal gland  Adenosine › Chemical that triggers sleepiness (high levels = sleepiness)  Melatonin › Levels rise as it gets darker (makes us ready for sleep!)

6.  Pons: Involved in REM sleep › Sends signals to shut off spinal cord  Thalamus: helps us tune out sensory signals during sleep

8.  Bright light at night delays sleep  Thinking is sharpest and memory is most accurate when we are at our daily circadian peak  After pulling an all nighter you may get a second wind after your normal wake-up time arrives

9.  Awake/Relaxed › Alpha waves: slow brain waves › Beta waves are alert, waking waves

10.  Stage 1: › Irregular brain waves › Slowed breathing › Hypnagogic Sensations:  Similar to hallucinations  Floating weightlessly, falling, etc  Stage 2 (after 10-15 minutes): › Sleep spindles – bursts of rapid, rhythmic brain wave activity › Could be awakened without too much difficulty › Spend 50% of the night here Sleep talking usually occurs in these stages!

11.  Stage 3: › Delta waves: large, slow waves  Stage 4: › More delta waves › Deep sleep  Hard to waken you during these stages (disoriented)  Sleep walking usually occurs here

12.  Heart rate rises, breathing becomes rapid and irregular, eyes dart around  Brainwaves resemble waking brain waves  However, brainstem blocks the messages from the motor cortex (although it is active) › Paradoxical Sleep  20% of the night is spent here

14.  With each 90-minute cycle, stage 4 sleep decreases and the duration of REM sleep increases

15.  Sleep protects › A species sleep patterns suits its ecological niche  Animals with the greatest need to graze and the least ability to hide tend to sleep less  Helps us recuperate, restore, and repair brain tissue  Helps us restore and rebuild our fading memories  Helps creativity  May play a role in the growth process (pituitary gland releases growth hormone)

17.  Insomnia  Apnea  Nightmares v Night terrors  Narcolepsy