Safety and OSHA News

What’s better for safety: Daytime or split sleep schedules?

Know nighttime workers who are frustrated trying to sleep for eight hours during the day? A new study provides them with an option.

New research, Investigation of the Effects of Split Sleep Schedules on Commercial Vehcle Driver Safety and Health, shows a split sleep schedule is better than consolidated sleep during the day. The best bet is still consolidated sleep during the night.

Among test subjects, a consolidated nighttime rest period provided the most sleep: 8.4 hours on average. The split schedule was the second best, averaging 7.2 hours of sleep. Consolidated daytime rest was the worst, averaging just 6.4 hours of sleep.

The study was conducted for the Federal Motor Carrier Safety Administration by sleep scientist Gregory Belenky of Washington State University.

The purpose of the study: The FMCSA’s current truck driver hours of service rule allows for split sleep periods, but says the required 10 hours of rest must include at least one eight-hour period.

The new study tested two periods of five hours each (3-8 a.m. and 3-8 p.m.).

The conclusion: It’s possible the HOS rules could be relaxed to allow drivers more flexibility in choosing their rest periods without their safety performance being compromised.

While getting eight hours of sleep per day is important, this study shows it doesn’t have to come mostly in one long period.

Sleep and circadian rhythm

The natural sleepiness we feel during certain times of the day are due to the body’s circadian rhythm — a biological process that allows most people to operate on a 24-hour cycle.

When circadian rhythms are lowest, at 2-4 a.m. and 1-3 p.m., adults’ strongest sleep drives occur.

Combining that information with the new research on split-sleep periods could help night shift workers get eight hours of sleep per day.

Example: A worker’s regular shift is 5 p.m. to 1 a.m. After the shift, and worker has to drive home and then wind down before going to bed. Let’s say that means the worker doesn’t feel like going to bed until 3 a.m.

But, the worker finds he usually wakes up around 8 a.m., only getting about five hours of sleep.

The worker could take advantage of the body’s secondary low circadian rhythm period between 1-3 p.m. and get three more hours of sleep during the early to mid afternoon.

Do you know any methods shift workers use to get their full eight hours of sleep per day? What do you think about this new study? Let us know in the comments below.

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  1. I dislike working nights, and really feel for folks that have to do it on a regular basis. I recently read a study that examined sleep patterns during the middle ages that found that the social norm was 2 sleep periods per day, but both occuring during the night. In between, people would do indoor chores, stoke the fire, or even visit neighbors. Interesting study.

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