What impacts can shift work have on your cognitions and behaviour?
lack of concentration, memory impairment
no motivation or energy
What is a circadian rhythm?
changes that occur on a 24 cycle (e.g. sleep wake cycle)
What is melatonin?
hormone that makes you feel drowsy and tired
What is R.E.M sleep?
sleep that occurs at intervals, rapid eye movements, more dreaming, faster breathing and pulse
What is non-R.E.M sleep?
dreamless sleep, slow brainwaves, regular breathing and heart rate, sleep is still
What is a zeitgeber?
external cue such as light which influence internal biological rhythms
What is phase advance?
a forward shift in the sleep/wake cycle, when a person brings forward when they go to sleep
What is the superchiasmatic nucleus (SCN)?
part of the brain involved in controlling circadian rhythms, acts as internal clock
What is phase delay?
a backward shift in the sleep/wake cycle, when a person holds back when the go to sleep
What is a phase response curve?
curve describing the relationship between stimuli and responses, such as light exposure and shift in circadian rhythms
What triggers a melatonin release?
sunlight is received by your eyes , the SCN receives this cue and makes sense of it, this activates hormones such as melatonin to release
What is an ultradian rhythm?
biological changes that occur in cycles of less than 24 hours
What are the 5 stages of sleep? and what are their key features?
one -> reduction in heart rate, muscle tension and temperature
two -> brain waves are slow and large, easy to be woken
three -> long slow waves, deeper sleep
four -> little muscular activity, temp drops, night terrors, hard to wake
REM -> active brain, body paralysis, hard to wake
What are the physiological benefits of sleep?
muscles repair
blood pressure drops
decreased heart rate
What are the psychological benefits of sleep?
release of serotonin
improved mood
better concentration
What happened to Peter Tripp?
stayed awake for 11 days issues with concentration paranoia and hallucination delusions when asked to subtract 7 from 100 repeatedly, he stopped at 65 and said he forgot the task
How can shift work interrupt/disrupt circadian rhythms?
when working night shifts, melatonin could be released due to lack of daylight which could cause drowsiness
What happens to our biological rhythms when travelling East to West?
phase delay
have to stay up later to travel to time zones behind our own
suppress melatonin
What happens to our biological rhythms when travelling West to East?
phase advance
have to try to make yourself sleep earlier
body tries to release melatonin early
Why is phase delay easier than phase advance?
because you can conserve melatonin to help it to be released later, but our bodies are not able to automatically produce melatonin without zeitgebers
What was the aim of Czeisler’s study?
investigate the effects of shift work on circadian rhythms, looking at direction and intervals of shift patterns
What was the sample used by Czeisler?
83 males aged 19-68 on rotating shifts
68 males aged 19-86 on non-rotating shifts
Great Salt Lake Cooperation in Utah
What 2 research methods were used in Czeisler’s study?
self report
experiment
What self report method did Czeisler use? when was it used? what was the response rate?
questionnaires measuring satisfaction, health and productivity
before and after the new schedules were introduced
84% of sample completed
What did the questionnaires find out before the new schedules?
29% of workers were falling asleep at work
State 3 results that Czeisler’s study found?
when using a 21 day rotation complaints dropped from 90%-20%
81% said it only took 2-4 days to adjust to the new schedule
only 26% weren’t able to adjust
What was the main conclusion from Czeisler’s study?
that phase delay minimised negativity and increased productivity
What is one strategy to reduce the effects of jet lag?
natural light therapy - exposing your eyes to light at different times can help your CR shift (wearing sunglasses to help release melatonin)
How ethical is natural light therapy?
very as its something you can do yourself and its your choice
Will natural light therapy work for everyone?
won’t work for people with sight difficulties as they can’t tell the difference between light and dark as easily
What is one strategy to reduce the effects of shift work?
avoid shifts starting at 5/6am - by starting this early, melatonin is still in its 12 hour release period so will make you more tired
How ethical is avoiding shifts starting at this time?
more ethical
employee’s sleep patterns will be less interrupted
Will avoiding these shift times work for everyone?
won’t work for people with irregular shifts such as emergency services as they may have to start at this time