Disrupting Biological Rhythms

Write down all you know about the disruption of biological rhythms

Add your name and then swap papers Mark the work based on the following success criteria

Success criteria = Max 80 marks Mentions jet lag = 5 points Explains jet lag = 10 points Mentions shift work = 5 points Explains shift work = 10 points Key terms = 5 points each (Circadian rhythm, oscillators, SCN, melatonin, phase delay, phase advance, desynchronisation)

Objectives I can describe some effects of jetlag I can explain why jetlag affect us using ideas about circadian rhythms. I can evaluate theories using AIDS E C A The Big Question…. Discuss the disruption of biological rhythms (8+16)

Disruption of biological rhythms So far we have found out that biological rhythms are controlled by endogenous pacemakers or oscillators. Some of these oscillators can easily be reset by exogenous zeitgebers, whereas others are more resistant. This means that sometimes, our oscillators can become desynchronised – out of time with each other.

How are our circadian rhythms disrupted? Our circadian rhythms can be subject to; – Phase advance (West to East) – e.g. having to get up earlier than usual – Phase delay (East to West) – e.g. going to bed later than usual Which do you think is easiest to deal with? Why?

Does the direction of travel make a difference to jet lag? East to West Phase delay. Easier to cope with – like going to bed later Will be ready for bed earlier, but biological clock will wake us up earlier too West to East Phase advance – harder – like getting up earlier Trying to adjust to a shorter day so disruption to circadian rhythm is more pronounced Daylight, social zeitgebers and clocks tell us it is morning when we may still be wanting to sleep Recht et al 1995 – jet lagged baseballers p8

Watch the Video show/watch/explaining-jet-lag / show/watch/explaining-jet-lag / 0S0 0S0

Jet Lag News Report UK breakfast TV want to do a similar piece but wish to take a more 'expert approach'. Use your knowledge to make a script or video for the TV

Objectives I can describe some effects of shift work I can explain why shift work affects us using ideas about circadian rhythms. I can evaluate theories using AIDS E C A The Big Question…. Discuss the disruption of biological rhythms (8+16)

The causes of the accident are still described as a fateful combination of human error and imperfect technology. Chernobyl nuclear disaster th April am

The Exxon Valdez oil tanker struck Bligh Reef, off the coast of Alaska, at around 12:04 am March 24th, March 24th1989 The accident resulted in the discharge of approximately 11 million gallons of oil 20% of the cargo, into Prince William Sound. The third mate failed to properly manoeuver the vessel, possibly due to fatigue and excessive workload

What do these 2 disasters have in common? Both happened in the early hours of the morning. Both were thought to be caused by human error caused by disrupted biological rhythms!

Shiftwork (shift lag) Can have a harmful effect on health and well being. Major cause is disruption of circadian rhythm Body trying to function in complete opposite way to the instructions by Endogenous pacemakers and exogenous zeitgebers. Be alert at night and sleep during the day against the cues from zeitgebers.

Circadian Trough Boivin et al Night workers experience decreased alertness (at around 6am) – Circadian ‘trough’ Core body temperature takes even longer to re-set, which may affect performance (below optimum temperature for body functions e.g. enzymes) Artificial lighting only slightly effective in re- setting rhythm

Poor quality of sleep, partial sleep deprivation More difficult to sleep in day: Body clock doesn’t adjust completely More noise and disturbances in the day Daytime sleep 1-2 hours shorter than at night REM particularly affected (Tilley and Wilkinson, 1982) Consequence is sleep deprivation – makes circadian trough worse!

Effects on health Knutsson (1986) – many studies show significant relationship between shiftwork and heart disease. Those who worked shifts for over 15 years 3x more likely to develop heart disease Martino et al (2008) shift work is linked to all types of organ disease.

Commentary on ShiftWork Shiftwork has negative effects Individual differences – Reinberg et al 1984 Some workers are able to cope with shifts because their rhythm changed Less Shift workers also experience social disruption – can’t spend time with friends and family Gold et al More problems with rotating shifts than fixed shifts (all nights) Harmful effects can be reduced 1.If rotating shifts are unavoidable Phase delay (get up and go to bed later) is less disruptive than phase advance (get up and go to bed earlier) 2.Czeisler et al 1986 Bright lights can mimic the effect of daylight and re-set body rhythms (temp and cortisol) in 3 days (usually takes 9 days to adjust to a phase advance of 6 hours). The strong light entrains all rhythms not just the sleep wake cycle The strong light entrains all rhythms not just the sleep wake cycle

Applying this research Read ‘Reducing the harmful effects’ section on p9 Use this and what you have learned about the effects of shiftwork to write a letter or an info sheet for a new company about to employ shift workers (15-20mins)

Objectives I can describe some effects of shift Work I can explain why Shift Work affect us using ideas about circadian rhythms. I can evaluate theories using AIDS E C A The Big Question…. Discuss the disruption of biological rhythms (8+16)

Homework Plan and write the essay! Discuss research relating to the disruption of biological rhythms (24 marks)