PSYCH SAC 3 Flashcards
circadium rhythm
Our preference to sleep at night and be up during the day is tied to a circadian rhythm. A circadian rhythm involves changes in bodily functions or activities that
occur as part of a cycle with a duration of about 24 hours.
ultradian rhythms
-An ultradian rhythm involves changes in bodily functions or activities that
occur as part of a cycle shorter than 24 hours
-Ultradian rhythms include our heartbeat, respiration, hunger and eating
behaviour, secretion of different types of hormones, the activity of certain
neurotransmitters in the brain (such as dopamine and noradrenaline) and
alertness and activity levels.
supracharistmatic nucleus
An area of the brain’s hypothalamus called the supra-chiasmatic nucleus
(SCN) is considered to be the master biological clock that regulates the timing
and activity of the sleep-wake cycle. The SCN responds to light and controls the production of melatonin, a hormone that makes us feel drowsy
melatonin
The amount of melatonin present in the blood is associated with
alertness. Higher melatonin levels are associated with greater drowsiness and vice versa. When there is less light, the SCN signals the pineal gland to produce and
secrete more melatonin, {“Dracula of hormones”) which will make us drowsy
and induce sleepiness
Non-Rapid Eye movement
Non-rapid eye movement (NREM) sleep encompasses three sleep stages. While unique mental processes characterize each stage, they share a tendency for the sleeper to experience slowed breathing, muscle activity, heartbeat, and brain waves.
N1
NREM stage 1 (N1) is when sleep begins in the first sleep cycle and is a
period of relatively light sleep. Physiological changes that indicate a lower level of bodily arousal - a
decrease in heart rate, breathing, body temperature and muscle tensionare all evident in
N2 [50% of sleep]
This is often seen as the point where true sleep begins. We spend about 20
minutes in stage 2 sleep in our first NREM/REM sleep cycle. Physiological changes that were present in N1 continue in N2 (eg a decrease in heart rate, breathing, body temperature and muscle tension) N2 sleep is characterised by the appearance of sleep spindles (short bursts
of rapid brainwave activity)
N3
NREM Stage 3 (N3) is a period of deep sleep. Our heart rate and breathing slow to their lowest levels. Our muscles are completely relaxed. There are no eye movements. Brain waves become even slower, with the largest and slowest brain waves, called delta waves, becoming predominant. They occur more than 50% of the time in N3.
Rapid-Eye Movements
REM sleep is also called paradoxical sleep -internally, the brain and body
are active, while, externally, the body appears calm and inactive (atonia) REM
sleep periods lengthen and occur closer together as a sleep episode
progresses. The body’s internal functioning is more active during REM sleep than during NREM sleep. The heart rate is faster and more irregular. Blood pressure rises, and breathing is shallower, faster and more irregular when compared with NREM sleep
trends in the demand for sleep
As people age, total sleep time decreases i.e. less sleep time in the 24 hour circadian cycle
- as people age, number of awakenings increases i.e. sleep becomes more fragmented
- REM proportion markedly decreases from about 50% between 0–2 years, then stabilises at about
20–25% through to very old age
- age-related increase in NREM sleep proportion through infancy and early childhood
- decrease in time spent in NREM and REM that persists through to a very old age, especially from
birth for REM and early childhood for NREM
- decrease in proportion of NREM deep sleep, especially a marked decrease or disappearance in late adulthood/very old age (e.g. by age 90) i.e. less deep sleep and more light sleep
- in later adulthood, at around 60 or so, sleep is mostly stage 2 light sleep.
affects of sleep deprivation on a persons affective, behavioural/cognitive functioning
A: compromises brains ability to process emotional information and make accurate emotional perceptions/responses
B: sleep “inertia” occurs which impairs even the simplest daily tasks, such as motor and reaction time functions, as well as reduces our effiencey and timeliness
C: causes lapses of selective attention and a reduced ability to divide our attention and our memory and learning processes.
sleep deprivation compared to a BAC of 0.05 and 0.10
Dawson and Reid experiment, exploring the relationship between sustained sleep deprivation and the effects of alcohol on a persons effective functioning.
found that 17 hours of sustained wakefullness was equivalent to a BAC of 0.05 and 24 hours of wakefulness was equivalent to a BAC of 0.10.
sleep disturbance
sleep disturbance is used to refer to any sleep-related problem that disrupts an
individual’s normal sleep–wake cycle, including problems with sleep onset, waking from sleep
and abnormal behaviour occurring during sleep.
primary sleep disorder
a persistent sleep disturbance that cannot be attributed to another condition, such as another sleep disorder, a mental health or medical problem, or use of a legal or illegal drug
secondary sleep disorder
nvolves a sleep disturbance that is a by-product of or results from another condition, or use of a substance.
