Stages and Cycles of SleepFalling Asleep: From Alert to AlphaNon-REM Stages of SleepSlide 4REM SleepSlide 6How Much Do We Sleep?Slide 8Effects of Sleep Loss/DeprivationSleep Loss Effects by Body SystemSleep Loss/Deprivation=Accident RiskSleep Hygiene How to Sleep WellSleep DisordersSlide 14DreamsWhy Do We Dream?Theories about Functions of DreamsStages and Cycles of SleepSleep stages refer to distinct patterns of brain waves and muscle activity that are associated with different types of consciousness and sleep. There are four types of sleep.Sleep cycles refer to the patterns of shifting through all the sleep stages over the course of the night. We “cycle” through all the sleep stages in about 90 minutes on average.Falling Asleep:From Alert to AlphaEyes ClosedAlpha waves are the relatively slow brain waves of a relaxed, awake state (drowsy)Non-REM Stages of Sleep•NREM-1: light sleep from which you can be easily awakened–Brain wave pattern becomes more irregular and slower–Change from Alpha waves to NREM-1•NREM-2: deeper level of sleep characterized by sleep spindles–Breathing and heart rate slow–More difficult to be awakened•NREM-3: deepest level of sleep–Slow and large delta wavesNon-REM Sleep Stages Getting deeper into sleep…but not dreaming yet NREM-1 NREM-2NREM-3REM Sleep REM (Rapid Eye Movement) High level of brain activityDreaming occurs most often hereHeart rate rises and breathing becomes rapid.“Sleep paralysis”,”paradoxical sleep”: the brain is active but the body is immobile Brainstem blocks the motor cortex’s messages and the muscles don’t move.Genitals are aroused (not caused by dream content) and stay this way after REM is over.What happens during REM sleep?Stages of Sleep: The 90 Minute Cycles Through 8 Hours of SleepThe length of REM sleep increases the longer you remain asleep.NREM-1NREM-2NREM-3How Much Do We Sleep?1. Sleep protected our ancestors from predators. 2. Sleep restores and repairs the brain and body.3. Sleep builds and strengthens memories. 4. Sleep facilitates creative problem solving.5. Sleep is the time when growth hormones are active.Why do we sleep?What does sleep do for us?Effects of Sleep Loss/DeprivationREM sleep deprivation has the most detrimental effects.Inadequate sleep can make you more likely to:lose brainpower.gain weight.get sick.be irritable.feel old.Sleep Loss Effects by Body SystemSleep Loss/Deprivation=Accident RiskSleep loss results in more accidents, probably caused by impaired attention and slower reaction time.Accident FrequencySleep HygieneHow to Sleep Well1. Turn the lights low and turn all screens off.2. Eat earlier, and drink less alcohol and caffeine.3. Get up at the same time every day.4. Exercise (late afternoon is best). 5. Don’t check the clock; just let it happen.6. Get counseling for anxiety and depression.Sleep Disorders•Insomnia: persistent inability to fall asleep or stay asleep•Narcolepsy: (“numb seizure”): sleep attacks, even a collapse into REM/paralyzed sleep, at inopportune times•Sleep apnea (“with no breath”): repeated awakening after breathing stops refer to sudden scared-looking behavior, with rapid heartbeat and breathing.run in families, so there is a possible genetic basis.Are these people dreaming?These behaviors, mostly affect children, and occur in NONREM-3 sleep. They are not considered dreaming.Dreamsthe stream of images, actions, and feelings, experienced while in REM sleepWhy Do We Dream? Psychoanalytic TheoryWish fullfilment: “Psychic safety valve” – often express unacceptable feelings/desiresManifest content: the surface story (symbolic, actual dreams)Latent content: the dream’s disguised psychological meaning (Hidden message)Why Do We Dream?•Information Processing–Sort out our day’s events and consolidate our memories•Physiological Functions–Help develop and preserve neural pathways •Activation-synthesis theory–Dreams do not serve any specific function•Brain is bombarded with random neural activity during REM sleep•The cerebral cortex creates a plausible story from these random firings•Cognitive Developmental theory–Dreams reflect the dreamer’s cognitive development – his/her knowledge and understandingTheoryWish fulfillment (psycho-analytic theory)Information-processingPhysiological functionActivation-synthesisCognitive-developmental theoryTheories about Functions of DreamsSort out the day’s events and consolidate our memories.REM sleep triggers impulses that evoke random visual memories, which our brain weaves into stories.Lacks any scientific support; dreams may be interpreted in many different waysWhy do we dream about things we have not experienced?Does not explain why we experience meaningful dreamsDoes not address the neuroscience of