4.1 What is Consciousness

• Consciousness

  • refers to a state where we are aware of internal and external stimuli
    • awareness of internal stimuli includes feeling:
      • pain,
      • hunger
      • thirst
      • sleepiness
      • awareness of one’s thoughts and emotions
    • awareness to external stimuli includes experiences such as:
      • seeing the light of the sun
      • feeling the warmth of a room
      • hearing the voice of a friend

• We experience different states of consciousness on a regular basis

  • We might describe it as a continuum between full awareness to deep sleep.

• Sleep

  • a state marked by relatively low levels of physical activity and reduced physical awareness

• Wakefulness

  • a state characterized with high levels of sensory awareness, thought, and behavior

• There are plenty of states of consciousness that people experience:

  • These ranges from daydreaming, intoxication, and unconsciousness due to anesthesia.

Biological Rhythms

• these are internal rhythms of biological activity (eg. menstrual activity)

• some biological cycles fluctuates cyclically over a 24-hour period.

  • these cycles are called circadian rhythms
  • examples of these are the sleep-wake cycle and our body temperature cycle.
  • some circadian rhythms play a role in changes in our state of consciousness

• Since we have biological rhythms, we also keep a biological clock in our brain.

  • Inside the hypothalamus, the clock mechanism of the brain lies on the suprachiasmatic nucleus (SCN)
  • Light-sensitive neurons in the retina provide information to the SCN based on the amount of light present.
  • This basically says that our internal clock is based on or is synchronized to the amount of light in our environment.

Problems with Circadian Rhythms

• For most people, our circadian cycles are aligned with the outside world.

  • (eg. most people are wake during the day and are asleep during the night)

• The hormone melatonin helps regulate this sleep-wake cycle.

  • Melatonin is secreted by the pineal gland located inside the brain.
  • It is also thought that the pineal gland is involved in the regulation of various biological systems during sleep
  • The release of melatonin is stimulated in darkness and inhibited by light.

• While our circadian cycles are aligned with the outside world, there are individual differences to our sleep-wake cycle (eg. some people wake up early, while others consider themselves night owls)

  • These individual differences in circadian patterns of activity, are known as a person’s chronotype.
  • Research also show that morning people and night owls have different sleep regulation processes.
    • Sleep regulation refers on how the brain switches between sleep and wakefulness, while coordinating with this cycle to the outside world.

Disruptions in Normal Sleep

• Some situations can put a person’s circadian clock out of sync with the environment.

  • One way that it could happen is when we travel across multiple time zones, we often experience jet lag
    • Jet lag happens because there is a mismatch between our new environment and our internal circadian cycle, which have adapted to our previous environment,
    • Symptoms of jet lag include fatigue, sluggishness, irritability, and insomnia.
  • Individuals who do rotating shift work are also likely to experience disruptions in circadian cycles.
    • Rotating shift work refers to a work schedule that drastically changes from early to late on a daily/weekly basis.
    • This work schedule is common for people working in healthcare professions, and in service industries.
    • This results in sleeping problems that can lead to signs of depression and anxiety, and often associated with persistent feelings of exhaustion and agitation.
      • These may allow individuals prone to making mistakes during the job
      • A study had also shown that nurses who worked rotating shifts had affected their relationships with their family

• Disruptions in circadian rhythms can have negative consequences, there are things we can do to realign our biological clocks.

  • One example is using bright light to alleviate problems associated with jet lag, or consequences of rotating shift work.
  • This works because our biological clock is driven by light.
    • Research shows that exposure to light on working shifts and exposure to dark when not working can help combat insomnia and depression.

Insufficient Sleep

• When people have difficulty getting sleep due to work or everyday demands in lift, they may accumulate a sleep debt.

  • Sleep debt is a condition where a person does not get sufficient sleep on a chronic basis.
  • Due to bright light, people often experience consequences of reduced amounts of sleep.
    • This is because we are more active in the nighttime than our ancestors were, thanks to bright light.

• The table below shows the recommended, appropriate and not recommended sleep amounts divided according to age, as suggested by the National Sleep Foundation in 2015.

Age	Recommended	May be Appropriate	Not Recommended
months	hours	hours hours	hours hours
months	hours	hours hours	hours hours
years	hours	hours hours	hours hours
years	hours	hours hours	hours hours
years	hours	hours hours	hours hours
years	hours	hours hours	hours hours
years	hours	hours hours	hours hours
years	hours	hours hours	hours hours
years	hours	hours hours	hours hours

Effects of Sleep Debt and Sleep Deprivation

• Lack of sleep can result in decreased mental alertness and cognitive function.
• It also results in depression-like symptoms.
• It is also associated with:
  • obesity
  • increased blood pressure
  • increased levels of stress hormones
  • reduced immune functioning
• Sleep-deprived individuals may have difficulty staying awake when they stop moving.
  • This can put themselves and others at risk, especially when they drive a vehicle or work with dangerous machinery.
• Some research suggests that sleep deprivation affects cognitive and motor function more effectively than being intoxicated with alcohol.
• Severe effects of sleep deprivation occur when:
  • a person stays awake for more than 24 hours, or
  • a person spends repeated nights staying in bed fewer than four hours.
• A person with fewer than 4 hours of sleep may experience:
  • irritability
  • distractibility
  • impairments in cognitive and moral judgement
• A person may start experiencing hallucinations after staying wake for 48 consecutive hours.