Human Consciousness and Sleep Flashcards
What is the difference between selective and divided attention?
Selective attention is when an individual’s attention is only focused on a limited range of all that they are capable of experiencing. If a situation is personally important, for example, they are likely to pay close attention to it. Alternatively, divided attention is the ability to share attention between two activities.
How do brain structures and hormones regulate and direct consciousness?
The hypothalamus, a structure of the brain, plays a major role in controlling emotion and motivated behaviours. This structure is in the forebrain.
Melatonin is a sleep hormone that is released when it is dark. Secreted from a small structure called the pineal gland, this hormone directs consciousness towards sleep.
What is the continuum of arousal (sleep to hyperarousal)
The continuum of arousal begins with a complete lack of awareness, like a comatose state. Anesthesia is the next level above this, with sleep right above. These two are altered states of consciousness. Divided attention (automatic) falls under normal waking consciousness, which occurs throughout the day. Focused selective attention (controlled) is an altered state of consciousness too, and is at the end of the continuum. It is considered heightened awareness.
What techniques are used to measure consciousness?
Electroencephalogram (EEG), Electromyography (EMG) and Electrooculography (EOG) are all used to measure consciousness. EEG, developed in 1929 by Hans Berger, detects, amplifies and records electrical activity in the brain as brainwaves. Electrodes are placed on the outside of the head using a special cap. This process helps to determine what areas of the brain may or may not be working efficiently. It can be used in the diagnosis of disorders and medication choices.
EMG measures stages of sleep, and detects, amplifies and records the electrical activity of the muscles. The electrodes are attached to the skin directly above muscles, used to determine if the person is asleep or awake. Also used to see if they are in REM sleep or NREM.
EOG detects, amplifies and records activity in the muscles that allow eye movement. This measures changes in voltage as the eyes move or rotate in their sockets. This helps determine REM or NREM sleep.
What is the sleep-wake cycle and the stages of sleep?
The sleep-wake cycle is the biological process of alternating between sleep and wakefulness. There are two main phases of sleep, Rapid Eye Movement (REM) and Non-Rapid Eye Movement (NREM).
REM sleep is a period of sleep when the eyes move rapidly. The first cycle last about 10 minutes. This phase is lighter than stages 3 and 4 of NREM sleep, and is the easiest to wake up from. This is also the phase when dreaming occurs.
NREM sleep is characterised by little to no eye movement. It is divided into four stages, which are determined by brainwave patterns. Stage 1 lasts about 5 minutes of light sleep but can range from 30 seconds to 10 minutes. This could be where a person experiences hallucinations or hypnotic jerks.
Stage 2 is where true sleep begins. This lasts for 20 minutes, and is an easy stage to be woken up from. This consists of 50% of a person’s total sleep, and is where the body begins to relax.
Stage 3 is the start of deep sleep, where a person is less responsive and difficult to awaken.
Stage 4, the final stage, is the deepest sleep, and is the hardest to be woken from. That person can still be sensitive to some sounds, but many are excluded from this. This stage tends to last about 30 minutes, 1 hour after falling asleep first.
After these stages, the cycle repeats. It goes from stage 4 of NREM to 3, then 2, and instead of going back to 1, REM sleep is induced.
What are the theories of the purpose for sleep?
The evolutionary and restorative theories are the main theories of sleep.
The evolutionary theory suggests that animals need sleep for survival in their environment. For example, a smaller animal can sleep more to hide from carnivores, but larger animals sleep less because they are more exposed, and may need to escape. Sleep would also depend on the need to find food. Aligned with this, sleep conserves energy, which reduces the need for food.
Alternatively, the restorative theory states that sleep allows individuals to recharge their body. Sleep increases alertness, immunity to disease and activates a growth hormone. It also enhances mood.
Both of these theories have their criticisms, so neither is more correct than the other.
What are the physical and psychological effects of sleep deprivation?
Sleep deprivation can cause emotional disturbances, behavioural difficulties, cognitive difficulties and headaches, high sensitivity to pain, head tremors and low energy levels.
Total sleep deprivation tends to be at around 6 nights.
- 1 night- discomfort but tolerable
- 2 nights- urge to sleep especially between 2am and 4am
- 3 nights- tasks requiring concentration are seriously impaired
- 4 nights- periods of microsleep are unavoidable, irritable and confused, feeling of tightening around the head (hat phenomenon)
- 5 nights- may become delusional
- 6 nights- possible depersonalisation, difficulty coping with other people: sleep deprivation psychosis
Compare sleeping disorders (narcolepsy, sleep-onset insomnia, sleep apnoea and sleep walking)
Narcolepsy is when a person can lapse into REM sleep at any time, no matter how much sleep they had the night before. They can also experience cataplexy (remaining conscious but being physically paralysed). There is no treatment to this disorder.
Sleep-onset insomnia is when an individual has trouble falling asleep at the beginning of the night. While narcolepsy does not have a treatment, insomnia can be treated through cognitive behavioural therapy or medication. This disorder can cause stress and impairment, and can be influenced by other psychological disorders.
Sleep apnoea is the interruption of breathing during sleep. Breathing can stop for brief but repeated lengths of time, and is linked to snoring or disruption of sleep. If left untreated, heart problems, hypertension and mood or memory problems may arise. Insomnia could also be a result of this disorder. A CPAP device is treatment for this.
Sleepwalking occurs during stages 3 and 4 of NREM sleep. There is no treatment, and often this runs in families. Most people will simply stare blankly and not respond to others.
