Sleep Flashcards
sleep
a reversible state of perceptual disengagement from and unresponsiveness to the environment
biological rhythms
the cyclic changes in bodily functions or activities that repeat themselves through time
circadian rhythms
occur over 24 hours
light
the main environmental cue that influences the sleep-wake cycle
suprachiasmatic nucleus
the master biological clock that regulates the timing and activity of the sleep-wake cycle
process of the SCN to the bloodstream
- receives information about the amount of incoming light from the eyes and adjusts the sleep-wake cycle accordingly
- sends messages to the pineal gland to secrete more or less melatonin
melatonin
a hormone that induces drowsiness
- more light = less melatonin
- less light = more melatonin
ultradian rhythms
involves changes to bodily functions or activities which occur as part of a cycle shorter than 24 hours
sleep episode cycles
- 1 2 3 4 3 2 REM
- 2 3 4 3 2 REM
- 2 3 2 REM
- 2 REM
- 2 1 awake
NREM
- 75-80% of sleep
- successive stages indicate deeper sleep
sleep onset
the transition period between being awake and asleep
sleep latency
the length of time it takes to fall asleep
NREM stage 1
- occurs as we drift in and out of sleep
- can easily be reawakened
- low arousal threshold
- about 5% of total sleep time
NREM stage 2
- the point at which we can be said to be truly asleep
- can be easily aroused
- higher arousal threshold than stage 1
- around 50% of total sleep time
NREM stage 3
- start of deep sleep
- if awoken, a person is groggy and disoriented
- around 3-8% of sleep time
NREM stage 4
- the deepest stage of sleep
- very difficult to awaken
- around 10-15% of sleep time
REM
- spontaneous bursts of rapid eye movement
- 20-25% of total sleep time
restoration theory
proposes that sleep provides time to help the body recover from depleting activities during the day
REM and NREM sleep restoration factors
- REM: restores the mind
- NREM: restores the body
REM rebound
catching up on REM sleep immediately following a period of lost REM sleep by spending more time than usual in REM when next asleep
evidence for the restoration theory
- people usually sleep for a longer period of time during illness
- most people feel tired before sleeping and energised after waking up
limitations of the restoration theory
- no conclusive cause and effect of what is actually restored during sleep
- the amount of sleep does not necessarily change according to our level of daytime activity
evolutionary theory (circadian theory)
proposes that sleep evovled to enhance survival by protecting an organism
limitations of the evolutionary theory
- does not explain the need for sleep
- doesn’t account for loss of awareness during sleep
- -organism is disengaged during a need for high alert?
- overlooks the benefits of sleep for our mental wellbeing
newborn sleep patterns (birth - 2 months)
- 16 hours
- 50% REM
- sleep onset occurs during REM
- sleep episode consists of only one or two cycles
infant sleep patterns (2 months - 2 years)
- 13-14 hours
- 30-40% of REM
- NREM-REM cycles become more regular
- sleep onset begins during NREM 1
- typical NREM-REM cycle lasts 50-60 minutes