1.5 Sleep

Consciousness

our subjective awareness of ourselves and our environment

Sleep and wakefulness are two types of consciousness

Circadian rhythm

our biological clock and sleep/wake cycle

regulates bodily rhythms(ex temperature and wakefulness) that occur on a 24 hour cycle

As morning nears, body temperature rises ,it then peaks during the day, dips for a time in the early afternoon, and begins to drop again in the evening

Thinking and memory improve as we approach our daily peak in circadian arousal ex pulling an all nighter you feel groggy in the middle of the night, but as you approach your normal wake up time you have a sense of new alertness

age and experience can alter our circadian rhythm

Most teens and young adults are evening energized “night owls” while older adults are morning loving “larks”

Jet lag and shift work disrupt the circadian rhythm

Sleep stages

identified by their specific EEG patterns

1. Alpha waves- When you are in bed with your eyes closed you are in an awakened but relaxed state.

   Alpha waves are slow brain waves.

2. NREM-1 stage- You grow tired and slip into sleep. This transition is marked by slowed breathing and irregular brain waves. This is non-rapid eye movement sleep.

   NREM sleep occurs in stages 1-3, encompassing all sleep stages except for REM sleep, and decreases in duration throughout the cycle.

   During NREM-1 you may experience hallucinations(false sensory experiences, such as seeing something in the absence of an external visual stimulus).

   You may also have the sensation of falling or of floating weightlessly. These are hypnagogic sensations (bizarre experiences while transitioning to sleep) and they may stay in your memory.

3. NREM-2 stage- You then relax more deeply and begin about 20 minutes of NREM-2 sleep.

   In this stage you have sleep spindles( bursts of rapid, rhythmic, brain-wave activity)

   You could still be awakened without much difficulty, but you’re still asleep

   You spend about half of your night here

4. NREM-3 stage- Then you transition to the deep sleep of NREM-3. This sleep lasts for about 30 minutes

   Your brain emits large, slow delta waves

   You are hard to awaken

5. REM sleep- About an hour after you first fall asleep, not directly after NREM-3, This is rapid eye movement sleep

   For about 10 minutes, your brain waves become rapid and saw-toothed, more like those of nearly awake NREM-1 which is why REM is considered paradoxical because it produces waves similar to wakefulness, but the body is at its most relaxed

   But unlike NREM-1, during REM sleep your heart rate rises, your breathing becomes rapid and irregular, and every half minute or so your closed eyes dart around in momentary bursts of activity

   These eye movements announce the beginning of a dream-often emotional, usually story-like, and richly hallucinatory

   body Is paralyzed

   The frequency of REM sleep typically increases as the cycle progresses

   REM rebound- We need REM sleep. Deprived of it by repeated awakenings, people return more and more quickly to the REM stage after falling back to sleep. When finally allowed to sleep undisturbed, they sleep like babies-with increased REM sleep, a phenomenon called REM rebound

Young adult typical sleep cycle(not needed just example)

picture

Older adult typical sleep cycle (not needed just example)

picture +tip- A common mistake is that REM comes directly after NREM-3 sleep. It does NOT. Generally, NREM-2 follows NREM-3. Then comes REM

Suprachiasmatic nucleus (SCN)

Cell clusters in the hypothalamus that control the circadian rhythm

Helps monitor the brain’s release of melatonin, which affects our circadian rhythm

Why do we dream?

Activation synthesis theory, consolidation theory,

Activation synthesis theory

We dream because our brain is trying to make sense of neural static

Consolidation theory

We dream because it helps process and strengthen our memories and experiences

If you don’t get good sleep and enough sleep after your learn new stuff, you won’t remember it

sleep is useful for organizing and consolidating memories

Why do we sleep?

Memory consolidation theory and restoration theory

Restoration theory

We sleep because we get tired from daily activities and we sleep to restore our energy and resources

Restoring depleted resources used throughout a given day.

Insomnia

Having trouble falling or staying asleep

can be caused due to stress, medication, or an irregular sleep schedule

Results in tiredness and increased risk of depression

Narcolepsy

uncontrollable sleep attacks, often triggered by strong emotions

person collapses into brief period of REM sleep, with loss of muscular tension

REM sleep behavior disorder

Person acts out their dreams during REM sleep

the paralysis during REM sleep is absent or possibly incomplete

Sleep apnea

Hard time falling asleep or staying asleep because they are struggling with breathing-they stop breathing during sleep

loud snoring

many unaware of their disorder

associated with obesity

other warning signs are daytime sleepiness, irritability, and high blood pressure

Somnambulism (sleep walking)

Sleep walking or talking, normal waking activities while asleep

Sleep talking can occur during any sleep stage

Sleep walking happens in NREM-3 sleep

Few serious concerns