Studies have shown that a greater number of shift work accidents occur in the few days after the clocks change in the Spring or Fall than occur on average the rest of the year. When the clocks "spring ahead," there is a greater risk of fatigue because many people do not go to bed an hour earlier to compensate. If a worker has already accumulated sleep debt, the time shift only exacerbates the disruption to his sleep/wake (circadian rhythm) cycle. Such a significant fatigue state has cognitive detriments comparable to drunkenness.
When the clocks "fall back," circadian rhythm disruptions occur also despite the hour gained. Night shift workers must contend with repeating the same hour in the middle of the night. Although their shift schedules could be slightly altered or their pay adjusted to make up for the extra hour, there is still a price paid by their body clocks, and this still presents a safety risk. Plus, even when fatigue is not present, internal body clocks must still adjust to later sunrises and earlier sunsets, and because circadian rhythms are connected to the day/night cycle, it may take people longer after waking to feel alert in the morning, and they may start to feel tired earlier in the evening because the sun sets earlier. Our bodies need two or three days to fully adjust to the time change.
Be Vigilant About the Impact of Circadian Rythm on Shift Work
Companies should take steps to remind employees of these potential dangers and to be vigilant with regard to their fatigue and alertness levels. Predictive Safety's AlertMeter® can help ensure that the individuals in your workforce are alert and fit for duty before they start work. The dangers of lowered or compromised alertness are always present, because the dangers are numerous—fatigue, illness, medications, drugs and alcohol, emotional distress, and so on—and they can affect individuals at any time. Sometimes, however, these common causes are less random and can affect larger sections of a workforce at once, such as contagious illnesses and, of course, changing the clocks for daylight savings time.