Impact of Sleep on Cognition and Mood Mabel Lopez, Ph.D

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1 Part 1: Overview of Sleep 2 What is Sleep?

1 1 Part 1: Overview of Sleep 2 What is Sleep?! Sleep is a state of consciousness that we have no knowledge of being in until we wake up.! Sleep is defined by slowed breathing and irregular brain waves! We spend 1/3 of our life asleep; that s 25 years for the average person. 1

2 Why Do We Sleep? Evolutionary Theory: Protective function, keeps people tucked away at night, safe from predators. Recuperative Theory: Conserves energy, restores body tissues depleted during daily activity REM: hormones released that influence thinking & memory formation, mental organization; counteract fatigue, irritability, inattention NREM: body replenishes itself (tissue restoration and release of growth hormone) Why Do We Sleep At Night? Circadian Rhythm Circadian Rhythm Internally generated sleep/wake cycle connected to 24-hr period of earth s rotation Keeps us in phase with outside world Zeitgeber: any stimulus that resets the circadian rhythms (exercise, noise, meals, temperature, traveling (jet lag)) Why Do We Sleep At Night? Circadian Rhythm Circadian Rhythm Consistent despite lack of external cues indicating time time of day (no cues, slightly longer than 24 hrs) Rhythms faster bright light (trouble falling asleep) Rhythms slower dark (trouble waking up) Can adjust to hours (not 22- or 28) 2

The suprachiasmatic nucleus (SCN) is part of the hypothalamus and the main control center of the circadian rhythms of sleep and temperature. Located above the optic chiasm.

Light resets the SCN via a small branch of the optic nerve known as the retinohypothalamic path. Travels directly from the retina to the SCN.

3 The suprachiasmatic nucleus (SCN) is part of the hypothalamus and the main control center of the circadian rhythms of sleep and temperature. Located above the optic chiasm. Damage to the SCN results in less consistent body rhythms, no longer synchronized to environmental patterns of light and dark. Rhythms of Waking and Sleep! Light resets the SCN via a small branch of the optic nerve known as the retinohypothalamic path. Travels directly from the retina to the SCN.! The retinohypothalamic path comes from a special population of ganglion cells that have their own photopigment called melanopsin. The cells respond directly to light and do not require any input from the rods or cones. 9 3

4 Rhythms of Waking and Sleep! The SCN regulates waking and sleeping by controlling activity levels in other areas of the brain.! The SCN regulates the pineal gland, an endocrine gland located posterior to the thalamus.! The pineal gland secretes melatonin, a hormone that increases sleepiness (2-3 hrs before bedtime). Rhythms of Waking and Sleep! The SCN is genetically controlled and independently generates the circadian rhythms.! Single cell extracted from the SCN and raised in tissue culture continues to produce action potential in a rhythmic pattern.! Various cells communicate with each other to sharpen the circadian rhythm.! Sleep occurs in a recurring cycle of 90 to 110 minutes and is divided into two categories: Non-REM (four stages, 1-4) REM sleep (stage 5)! REM stands for Rapid Eye Movement.! Throughout the five stages, our brain waves continually fluctuate, thus defining each distinctive stage. 4

5 ! Beta- Awake, normal alert consciousness! Alpha-Relaxed, calm, meditation, visualization! Theta- Deep relaxation, meditation, problem solving! Delta-Deep, dreamless sleep Stages of Sleep: Pre-sleep stage! Awake and Alert Beta waves Functions: calm, alert, active, ready to learn May take about 15 minutes to go through this stage Adjust pillows, comforters, start to relax Stages of Sleep: Pre-sleep stage! Awake but Drowsy Alpha waves Functions: relaxed, harder to concentrate, want to go to sleep Hypnogogic Hallucinations Vivid images, bizarre Jerky movements Sensation of falling 5

6 Stage 1 Sleep: Alpha to Theta Waves! Non-REM Breathing slows down, movement decreases Disengage from sensation Vivid mental imagery Everyday activities, not bizarre dreams Can wake up spontaneously (falling out of bed) 2-5% of sleep Stage 2: Ahhh, Finally Asleep Congrats! You are officially asleep Small muscle twitches Breathing rhythmical ~50% of sleep in this stage Sleep talking occurs here Stage 2: Theta, K-Complexes, Sleep Spindles Stage 2 sleep is characterized by the presence of: Theta waves Sleep spindles to 14-Hz waves during a burst that lasts at least half a second (resist external stimuli) K-complexes - a sharp highamplitude negative wave followed by a smaller, slower positive wave (transition to deeper sleep and known to be decreased in AD, linked to B-amyloid deposit) 6

7 Stage 3: Theta - Delta - Theta! Non-REM Slow wave sleep Probably a transition stage sometimes not recognized as a stage) Parasomnias often occur here: sleepwalking, night terrors, talking during one s sleep, and bedwetting. Stage 4: Delta Waves Almost 100%! Non-REM Deep Sleep- hard to wake up Rhythmic breathing, relaxed muscles Restorative stage (hormones released) Oblivious to outside world Very disoriented if awoken at this stage Stage 4: Delta Waves 100% Sleep-walking, sleep-talking minutes at first and shorter each cycle Very difficult to wake up- but can have activities (Answer phone, talk, etc.) Children spend 40% of sleep Here! 7

Entering Stage 5.! Ascend back up through these stages and enter your 1 st dream! NREM Stages 1,2,3,4,3,2 then Stage 5/ REM sleep (Reminder: cycles are every 90-110 minutes)!

8 Entering Stage 5.! Ascend back up through these stages and enter your 1 st dream! NREM Stages 1,2,3,4,3,2 then Stage 5/ REM sleep (Reminder: cycles are every minutes)! Stage 3 and 4 sleep predominate early in the night. The length of stages 3 and 4 decrease as the night progresses.! REM sleep is predominant later in the night. Length of the REM stages increases as the night progresses.! REM is strongly associated with dreaming, but people also report dreaming in other stages of sleep. Stage 5, Dream State REM sleep, Paradoxical Sleep! REM lasts only about 10 minutes (20-30 minutes later in night)! Mimics beta waves + atonia = Dreaming! Also known as paradoxical sleep because it is deep sleep in some ways, but light sleep in other ways.! As the night progresses, we spend less and less time in stage 4 and more in REM.! 20 25% of the night in REM Sleep. 8

9 REM (Rapid Eye Movement)! Body functions during REM Brain neurons fire more Increased blood pressure Increased respiration Increased heart-rate ~30 seconds, eyes rapidly move Cortex is active BUT Body is paralyzed! Nightmares occur now = frightening, unpleasant dreams! No sleep walking during REM REM Rebound! The tendency for REM sleep to increase following REM sleep deprivation.! What will happen if you don t get a good nights sleep for a week, and then sleep for 10 hours? You will dream a lot. Dreams! A sequence of images, emotions, and thoughts passing through a sleeping person s mind.! An individual will have approximately 4-5 dreams/night (billions of dreams on earth each night) hours of sleep time spent dreaming They increase in length as the night progresses! Most mammals dream! Intense emotions, illogical, bizarre events are accepted! Most dreams erased from the conscious mind as we wake up, 5% of dreams can be recalled by human brain. 9

10 Why do we dream?! Many theories no one really knows??! Might relate to the idea that at this stage of rest we are Reviewing physical tasks Learning, integrating and consolidating knowledge Finding solutions to problems or working out difficult emotions Finding inspiration: songs, math proofs, art work Dealing with trauma used as a coping mechanism Rebooting the system used to refresh the brain after a long day Why do we dream? Evolutionary Theory Rehearsing what to do in an emergency: Threat simulation Dreams are a training ground in which we rehearse what to do in an emergency so you are more prepared to act on instinct. Two-thirds of all dreams involve some type of aggression (Physical fights, Arguments, Car crashes, Falling, drowning, Missing a meeting, Being lost or trapped) Our amygdala (the fight-or-flight piece of the brain) fires more than normal when we're in REM sleep In REM sleep, the brain fires in similar ways as it does when it's specifically threatened for survival Motor activity part of brain (running, punching) fires increasingly during REM sleep, even though the limbs are still Why do we dream? Activation-Synthesis! Activation Synthesis Model Dreams are products of brain neuron activity in the visual cortex, memory areas, and emotion areas. Hippocampus and the Amygdala No external stimulus; so brain tries to make sense of neuron activity = content of a dream Explains randomness of dreams Prefrontal cortex shuts down during REM So, you have fewer inhibitions and don t question illogical parts of dreams 10

11 Why do we dream? Crick & Mitchinson Theory! Crick and Mitchinson Theory "we dream in order to forget Dreams flush out excessive information or thoughts Dreaming is a shuffling of old connections that allows us to keep the important connections and erase the inefficient links (like defragmenting a hard drive) Why do we dream? Nightly Psychotherapy (!)! Emotional Processing Dreaming puts our difficult emotions into pictures Dreams allows us to deal with emotional content in a safe place, making connections that we would not make if left to our more critical or defensive awake brains Through processing emotions without rationalization, we come to accept truths we might otherwise repress. REM does increase after a stressful day Why do we dream? No reason at all Theory! Dreams have no meaning at all.! Dreams are the random firings of a brain that doesn't happen to be conscious at that time.! Perhaps it's only consciousness itself that wants to see some deep meaning in our brains at all times. 11

12 Part 2: Sleep, Cognition, & Mood 34 Lack of Sleep: Overall Cognitive Function *Lack of sleep defined as chronic sleep deprivation (sleeping 6 or less hours per night) 36 12

Lack of Sleep: Attention! Day time sleepiness and microsleeps 3 Failure to respond during cognitive demands Instability in cognitive performance, i.e., errors of omission and commission, which increases with time on task!

13 Lack of Sleep: Attention! Day time sleepiness and microsleeps 3 Failure to respond during cognitive demands Instability in cognitive performance, i.e., errors of omission and commission, which increases with time on task! Vigilance (sustained attention) reduced by almost 1 standard deviation 4 (that s 15 IQ points!)! PFC is critical structure in attention control *Lack of sleep defined as chronic sleep deprivation (sleeping 6 or less hours per night) Lack of Sleep: Memory! Failure to retain new information Sleep is needed to consolidate both procedural (skill) and declarative (knowledge) memories There is also data showing the importance of sleep in the integration of new information into existing networks! Decline in short-term recall and working memory *Lack of sleep defined as chronic sleep deprivation (sleeping 6 or less hours per night) Lack of Sleep: Academic Performance! Less sleep correlated with lower GPA! Cognitive slowing on selfpaced tasks, and time pressure increases errors *Lack of sleep defined as chronic sleep deprivation (sleeping 6 or less hours per night) 13

14 Sleep Deprivation and Mood! If people are deprived of Stage 4 sleep by waking them up each time they get to Stage 4 (i.e, deep/restorative sleep), they complain of being physically tired.! If people are deprived of REM sleep by waking them each time they have REM type EEG patterns, they can feel anxious and irritable. Sleep Deprivation and Mood! Medial PFC is less able to control amygdala (mood responses) when sleep deprived! Mood ratings 3 standard deviations below non-sleep deprived! More emotional reactivity Without sleep the brain's emotional centers were more reactive! Stress, depression, irritability increase Sleep Deprivation and Psychiatric Illness! Hallucinations: 80 % of normal people in the population will eventually have hallucinations if sleep-deprived long enough! Disorientation: confusion, delirium. First, lose track of time (mistaking the day, date, season, or year). Next, confused about place, not knowing where they are. Finally, in the extremes of disorientation, someone may not even know who they are.! Paranoia belief of being persecuted by some outside entity, not founded in reality. 14

15 ! Obesity Sleep Deprivation and Physical Illness! Malaise: feeling run-down or simply "not well! Aches, pains in body. fibromyalgia or other chronic pain conditions.! upset stomach or gastrointestinal symptoms diarrhea. Sleep Deprivation and other disorders! Sleep deprivation may lead to an increased risk of developing Alzheimers disease (e.g. Kang et al. 2009; Holzman et al. 2009)! Can look like Attention Deficit Hyperactivity Disorder (ADHD)! Can be misdiagnosed as psychiatric illness such as Bipolar Disorder (causes hypomania, pressure speech, thought disorder) *Lack of sleep defined as chronic sleep deprivation (sleeping 6 or less hours per night) Disorders of sleep: Sleep Apnea! A sleep disorder characterized by temporary cessations of breathing during sleep (hypoxia) and consequent momentary re-awakenings (fragmented sleep).! Associated with a higher risk of stroke! Associated with hypoxia! Associated with higher risk for dementia 15

16 Disorders of Sleep: REM Behavior Disorder! Act out violent (attacking, chasing) dreams during rapid eye movement (REM) sleep! Shouting, kicking, punching! When they wake up, they remember the dream! Often hurt themselves or bed partners! Associated with Lewy Body Dementia Disorders of Sleep: Narcolepsy! Characterized by uncontrollable sleep attacks.! Lapses directly into REM sleep (usually during times of stress or joy).! Genetic or due to TBI! Excessive Sleepiness, Hallucinations, and Cataplexy! Memory Impairments, Problems with Attention, Depression Disorders of Sleep: Insomnia! Recurring problems in falling, staying asleep, broken sleep, or waking up early without intending to, waking up tired (2 of these sxs)! Not your once in a while! Primary (not related to health condition) versus Secondary insomnia (related to illness or medication).! Acute (short term) or chronic (long term) 16

17 Disorders of Sleep: Insomnia! Problems with Working Memory, Memory, Concentration and Executive Functioning! Irritability! Mania! Depression! Anxiety! Hallucinations! Slurred Speech Part 4: Sleep Hygiene 50 How much sleep do you need?! CDC 7-9 hours! 7 per night is recommended minimum! Need to be consistent! 4 or more days with less than 7 hours of sleep start seeing deficits in cognition and mood 17

18 Tips for Better Sleep! Make Sleeping a priority VALUE IT! Treat it like food and water! Routine: Develop a sleep/wake schedule try to get to sleep and awake at the same time each day; an erratic sleep schedule causes difficulty in getting to sleep and waking up.! No all nighters! All nighters = confusion, attention and working memory for days Tips for Better Sleep! Avoid daytime napping napping disrupts the sleep schedule.! Avoid substances with caffeine, nicotine or alcohol before going to bed.! Don t drink caffeine after 12 noon! Keep lights low before bed (blue light blocking/ yellow glasses)! No screens (computers, televisions) for half an hour before sleep Tips for Better Sleep! Understand it doesn t require effort don t need to fight for it (Don t Worry about sleeping) Bed time routine! Reduce Anxiety Mindfulness Meditation Self-Hypnosis (iphone apps, Youtube, MP3s, audible.com, download from local library) 18

Tips for Better Sleep! Don t eat a heavy meal before going to bed.! Exercise 20-30 minutes a day, but avoid exercising 3-5 hours prior to bedtime.

19 Tips for Better Sleep! Don t eat a heavy meal before going to bed.! Exercise minutes a day, but avoid exercising 3-5 hours prior to bedtime.! Relax before bed take a warm bath or shower or read to ease into a sleep routine.! Control your room temperature. Tips for Better Sleep! Learn to associate your bed with sleeping and relaxing no studying, watching TV, doing work or paying bills.! Don t lie in bed awake if you can t get to sleep within a short amount of time, get up, read or do something quiet.! See a doctor if sleeping problems continue. Contact Info: Dr. Mabel Lopez Neuropsychologist Licensed Psychologist, PY7375 Mind and Brain Care , office 57 19

Consciousness, Stages of Sleep, & Dreams. Defined:

Consciousness, Stages of Sleep, & Dreams I. Consciousness Conscious is: Waking Consciousness Defined: Altered State of Consciousness Defined: Most of waking life Fuzzy, organized, bizarre thoughts Examples: