Disruption AO1

Jet lag

• Symptoms:

  • Difficulty sleeping at bedtime and waking up in the morning

  • Tiredness and exhaustion

  • Difficulty staying awake during the day

  • Poor sleep quality

  • Concentration and memory problems

• Phase advance: Travel west to east shortens day

• Phase delay: Travelling east to west extends day

Phase advance and phase delay

• Phase shift in circadian rhythm means bedtime and wake up time will move earlier or later in the day

• Many of us have heard that light exposure in the morning advances your rhythm, whereas light exposure in the evening delays it

• Siffre: Phase delay demonstrated by sleep-wake cycle shifting to 25 hours per day, sleep pattern averaging about 8.5 to 10 hours daily without natural light.

Shift lag

• E.g. night workers engages in shift work experience reduced concentration around 6 am (circadian trough) meaning mistakes and accidents are more likely (Boivin et Al)

• Research suggests a relationship between shift work and poor health

• Shift workers are 3x more likely to develop heart disease (Knutson) which may in part be due to the stress of adjusting to different sleep-wake patterns and the lack of poor quality sleep during the day

• Thus, research into the sleep-wake cycle may have economic implications in terms of how best to manage worker productivity

Effects of shift work

• Rotate shifts quickly, so cycle does not have time to entrain itself to a new cycle, therefore it is harder to manage (short term shifts)

• Night shifts all in a row, and a large gap between the next set is best way to do it.