Chapter 7: Consciousness Part II – Sleep

Sleep “The equalizer of presidents and peasants” Used to be full of mysteries – now we are starting to solve those mysteries We can measure brain waves and muscle movements and combined with watching, we are learning many things

Rhythms Life has rhythms like everything else on earth So does sleep Controlled by biological clocks In a 24 hours cycle we experience variations in alertness, body temperature, and growth hormone secretion Sleep has a rhythm and cycle too! – 90 minutes for humans

Circadian Rhythm It is the biological clock that occurs on the 24 hour cycle Temperature rises in the morning, peaks during the day, and dips in the early afternoon, and drops before bed time If you are awake in the middle of the night you may be more susceptible to depressed thoughts All nighter? Most tired at 4:00 am, although we may get a second wind at a normal “rising” time Jet lag! We have disrupted the cycle

The Role of Light Light is what tweaks the circadian clock Light-sensitive proteins trigger signals to the brains suprachiasmatic nucleus – 20,000 cells that control the circadian clock Pineal gland adjusts how much melatonin is being produced – Decrease melatonin production in the morning, increase at night (light and dark) Longer we are awake the more adenosine accumulates – Adenosine inhibits certain neurons, making us sleepy – Amount of adenosine decreases when we are asleep – Caffeine blocks adenosine activity

Sleep Stages Sleep overtakes, cortex stop communicating, consciousness fades Every 90 minutes we pass through 5 sleep stages We can measure the stages with electrodes, and EEG, and other devices to measure heart rate, respiration and genital arousal

Sleep Stage…Step-by-Step “Pre-Sleep”: Awake, but eyes are closed; slow alpha waves; fall asleep (enter into stage 1) Step/Stage 1: Sleep; slowed breathing; irregular brain waves; hallucinations (sensory experiences without sensory stimulus) – EX: body may suddenly jerk or you may feel like you are falling – Hypnagogic sensations – May later be remembered as memories

Sleep Stage…Step-by-Step Step/Stage 2: Sleep (still); more relaxation; lasts about 20 minutes; can be awakened easily; sleep talking; sleep spindles – Bursts of rapid, rhythmatic brain-wave activity Step/Stage 3: Sleep (yep…still); transitional stage; slower delta waves; 30 minutes long; hard to wake up Step/Stage 4: Deep sleep (still sleep – just deep); slow delta waves; 30 minutes; hard to wake up – Oddly, it is at the end of stage 4 that children wet the bed or sleepwalking begins

While We Are Sleeping….. Brain can still process certain stimuli We move in our beds and don’t fall out (we hope) Auditory cortex is still responding to sound (especially our names) An hour into sleeping, we do not stay in stage 4, we go back through stage 3 and 2 We spend half of the night in stage 2 – REM sleep

REM Sleep REM – Rapid Eye Movement 10 minutes at a time Brain waves are rapid and saw-toothed Heart rate rises; breathing more rapid and irregular; eyes dart around Genitals become aroused during REM (except nightmares) Motor cortex is active in REM, but brainstem blocks the messages, so your muscles stay relaxed Internally aroused, externally calm REM announces the beginning of a dream Not that we are watching our dream, but that nervous system is overactive

Sleep Through the Night Cycle repeats about every 90 minutes As the night goes on, stage 4 gets shorter and then disappears and REM gets longer We spend 20-25% of the night in REM Sleep stages Awake Hours of sleep REM

People Vary – Sleep Varies Most of us would sleep 9 hours if we set no clocks, routines or other hindrances There is no rule as to how many hours EVERY person MUST have Varies from person to person Age changes needs Genetics? Culture?

Why? Why do we sleep? 1/3 of our lives (25 years) If you want to know why – stay awake for 3 days and you will find out! Or watch someone who has been up that long

Sleep Deprivation Teenagers typically need 8-9 hours a night, but they average less than 7 When you don’t have enough sleep you function below your peak Depressed immune system, impaired concentration, vulnerability to accidents, diminished productivity, fatigue (duh), irritability,…to quote the book…it makes you stupid

Are You Sleep Deprived? disorders/excessive-sleepiness-10/breus- sleep-deprived disorders/excessive-sleepiness-10/breus- sleep-deprived Quiz: ,114.asp ,114.asp

My Teacher Lied!!! (Kinda) You can catch up on sleep We have a “sleep debt” Our body knows what we are behind and when we catch it up, it will go back to a normal requirement Volunteers were paid to stay in bed 14 hours a day. For the first few days most slept 12 hours Once they paid off their sleep debt, they went back to hours a night Millions of us are living in debt and living less than optimal lives 

And for the “kinda” part…. Many people sleep late on Saturday, hoping to compensate for sleep lost during the week. While sleeping late helps catch up on your sleep debt, it alters your sleep schedule. You sleep late one or two days and then wake up early again on Monday. Your body must adjust to these changes. During this adjustment, your quality of sleep is poor. It is much better to have a consistent daily sleep schedule that gives you 7 to 9 hours each night.

And…Despite What My Hubby Says Naps can be a great way to catch up on lost sleep. After taking naps, people function better and do certain cognitive tasks quicker. Napping can also help you train yourself to fall asleep quicker. However, napping longer than an hour or after 3 p.m. may make it more difficult for you to fall asleep at night.

Sleep Disorders  Insomnia  persistent problems in falling or staying asleep  10-15% if adults (17-20% of teens)  Sleeping pills and alcohol actually make it worse  Narcolepsy  uncontrollable sleep attacks  Last 5 minutes  1/2000 people  Must live with extra caution  Sleep Apnea  temporary cessation of breathing and momentary re- awakenings  Overweight men (most common)  “Loud snoring”

Night Terrors and Nightmares  Night Terrors  Mostly kids  high arousal-- appearance of being terrified  Double heart and respiration rate  Don’t usually wake up or remember anything  They are NOT nightmares  Occur within 2 or 3 hours of falling asleep, usually during Stage 4

End Day 2 Homework! Get permission to watch someone sleep (please ask and do not freak them out – it would be kinda creepy for you to watch them without them knowing) Watch them for 90 minutes (please do not multi-task, but only do things that do not draw away your attention/consciousness – auto pilot baby!) Write down your observations (this should keep you awake and alert) When done, summarize in 1-2 paragraphs and turn in with your notes