What is sleep in a physiological sense?
A period of reduced activity, associated with a typical posture and a decreased responsiveness to external stimuli. It is easy to reverse and shows physiological changes.
How many Australian adults don’t get enough sleep regularly?
~7.4 million Australian adults
How many deaths were estimated in 2016-17 due to lack of sleep?
What are the stages of a sleep cycle? (+Diagram)
Awake REM sleep nREM stage 1 nREM stage 2 nREM stage 3
What defines the 2 types of sleep?
Eye movement and electrical patterns in a sleeping person’s brain
What are the distinct stages of nREM sleep?
N1: Lasts 1 - 7 minutes and is defined by a low voltage, mixed-frequency pattern. N2: Forms spindles in the EEG recording and lasts 10 to 25 minutes. N3: Higher amplitude EEG waves and slow -wave activity and generally lasts 20 - 40 minutes.
What happens to depth of sleep when progressing from N1 to N3?
The sleep becomes deeper and brain becomes less responsive to external stimuli and it becomes increasingly difficult to awaken an individual from sleep.
What percentage of sleep is REM?
20 to 25% of total sleep in typical healthy adults.
What does REM sleep EEG look like?
low-amplitude, high frequency waves and alpha rhythm
What are the characteristics of REM sleep?
Rapid eye movements. Muscles in arms and legs are paralysed (could be a neurological barrier to acting out dreams) Visually intense dreams Hard to awaken, heart rate and BP also increased, core temperature not well regulated and sexual arousal is common.
When do night terrors typically occur?
When does dreaming occur most often?
Both REM and nREM
What are the theories on why we sleep?
Adaptive theory of sleep (inactivity is adaptive to keep away from danger) Theory of energy conservation (Helps us conserve energy and reduce expenditure when less productive) Restoration theory of sleep (Repair of injuries such as muscle growth, tissue repair, protein synthesis, and growth hormone, deficiency in growth hormone causes aches, and symptoms similar to depression) Information consolidation theory of sleep (Sleep is correlated with brain plasticity. Sleep is important for memory consolidation particularly during REM sleep)
What restorative mechanisms are active during sleep?
Growth hormone production Physical restoration (kidneys replenish salt stores, brain and muscles replenish sugar and fat stores) Cognitive functional restoration (Neurons in the brain produce adenosine. Adenosine buildup = tired feeling)
What stage of sleep is important for growth hormone production?
What are the characteristic changes to brain activity during sleep cycle?
Decrease in activation rate of most neurons from wakefulness to non-REM sleep. Patterns of neuron firing change from random and variable activity pattern during wakefulness to a more coordinated and synchronous pattern during non-REM sleep.
What happens to body temperature during sleep cycle?
Reduced during non-REM sleep and during REM falls to the lowest point.
What happens to respiratory changes during sleep cycle?
Breathing rate is irregular in both wakefulness and REM sleep and increases. Rate decreases and becomes more regular in nREM sleep.
What happens to cardiovascular activity during the sleep cycle?
Non-REM overall reduction in heart rate and blood pressure. REM sleep more pronounced variation with changes cardiovascular activity and increases in heart rate and blood pressure.
What overall physiological changes happen during sleep?
increased production of growth hormone in non-REM sleep. Physiological activities like digestion, cell repair, and growth are greatest during sleep.
Why is sleep important for cognitive functions and memories?
During our sleep the brain processes information, consolidates memories, and enables us to learn and function effectively during daytime. Sleep is important for reorganising memories and producing insight and creative ideas from those memories. Sleep affects ability to use language, sustain attention, understand what we are reading and summarise what we are hearing.
What percentage of Australian adults suffer from sleep deprivation?
33 - 45%
What is the average reported sleep time?
7 hours (12%< 5.5 hours and 8% > 9 hours)
What are the general symptoms of sleep problems?
Performance decrease: academic, physical, etc Behavioural difficulties Irritability Hyperactivity Frequent illness Headaches, jaw pain, earaches Daytime sleepiness Depression, anxiety
What causes sleep deprivation?
Personal choice (Watch TV, socializing) Attitude (Much sleep is not needed) Work Illness Sleep disorders Poor sleep behaviours Environment Distress/anxiety Ageing
What are the short term consequences of sleep deprivation?
Decreased performance and alertness Memory and cognitive impairment Stress relationships Poor quality of life Occupational injury Automobile injury
Long term consequences of sleep deprivation:
High BP Heart attack Stroke Obesity Psychiatric problems Mental impairment Childhood growth retardation Injury from accidents Poor quality of life Immune function reduction Increased inflammation
What mental illnesses are associated with sleep deprivation?
Anxiety Depression ADHD