Symptoms of a Disrupted Biological Rhythm
Slow reaction times
Impaired reasoning skills
Weakened immune system
Lack of concentration
Health and safety: Chernobyl & most lorry accidents happen in early hours
Work productivity: decreases because of the lack of concentraction and morale
Employee illness: increased stress and lowered immune system leads to more absences
Endogenous pacemakers become desynchronised with exogenous zeitgebers.
SCN signals to the pineal gland to produce melatonin when there are low levels of light, this causes sleepiness. Shift workers need to be awake at night so are fighting against the production of melanin (hence accidents happen).
Body temperature drops in the early morning - increasing drowsiness.
- phase delay (east to west) is easier to adjust to than phase advance.
- follow local exogenous zeitgebers
- melatonin tablets taken before bed
- forward/clockwise shift rotation (phase delay) easier to adjust to
- Czeisler (1982) says long shifts are best, Bambra (2008) says short are best.
- Exposure to pulse of very bright light can reset endogenous pacemakers
- Other exogenous zeitgebers, such as eating patterns and social interaction, can be used to adjust bodily rhythms.
Schwartz et al (95) - baseball teams from the east playing in the west (phase delay) won more games than teams from the west playing in the east (phase advance).
Czeisler et al (82) - Utah chemical plant had backward/anticlockwise shifts of 7 days. Changed it to forward/clockwise rotation of 21 days. 9 months later productivity and health had increased.
Bambra (2008) - found fast, forward/clockwise shift rotation to be best for health and work-life balance.
Dawson & Campbell (91) - exposed shift workers to 4hr pulse of bright light. Their body clocks reset.