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Big rigs, the circadian rhythm and driver alertness

Drowsiness affects every driver at one time or another, and it is especially dangerous for those who operate big rigs.

One element that figures into drowsiness is the circadian rhythm, a natural occurrence that is active at certain times of the day and night.

About the circadian rhythm

Everyone is subject to the drowsiness associated with the circadian rhythm, commonly known as the body’s wake/sleep cycle. This is all about the internal clock, the daily operating system. Humans are naturally drowsy between the hours of 12 a.m. to 6 a.m. and again in the afternoon from 2 p.m. to 4 p.m. These “lulls” are the most dangerous times for drivers to be on the road, because natural fatigue may compromise decision-making and slow the response to emergency situations.

FMCSA studies

The Federal Motor Carrier Safety Administration conducted studies showing that time of day affects the level of alertness more than time on task. Drivers are naturally less alert at night and more so after midnight, in line with the early-morning circadian rhythm lull. The FMCSA studies also found that the potential for an accident is highest in the first hour of driving after waking from sleep. Sleep inertia, as this is called, points to issues with reaction time, cognitive functioning and the struggle to remain awake.

Managing driver fatigue

The FMCSA urges truck drivers to pull over and take a nap if they become drowsy. They should not rely on excessive caffeine use because that will only cause headaches, nervousness and insomnia. Some drivers fight drowsiness by rolling down the window or turning up the radio, but that is merely a short-term fix, and drowsiness will eventually set in again.

Obeying the rules

Big-rig drivers must comply with a number of state and federal regulations. For example, they can only drive a certain number of hours in a day without taking a rest—but do they? As a motorist, you do not want to risk becoming an accident victim. Therefore, you must always remain alert around large trucks, especially during the hours that represent natural lulls in the circadian rhythm.