Tailoring the 'caffeine nap' to help drivers with obstructive sleep apnea manage tiredness behind the wheel

Researchers have developed tailored advice for drivers with obstructive sleep apnea after discovering that standard recommendations for managing driver fatigue may not be optimal for those with the condition. Driver sleepiness plays a significant role in road accidents. Drivers experiencing drowsiness are typically advised to stop, consume a caffeinated beverage, and take a 15-minute nap, collectively known as a caffeine nap.

This method aims to allow caffeine to take effect while the driver sleeps, thereby enhancing alertness upon waking. Previous research endorsing this advice primarily targeted the general population rather than individuals with obstructive sleep apnea (OSA), the most common sleep disorder affecting approximately one billion people worldwide.

OSA involves repeated interruptions in breathing during sleep, which can impact both health and daytime alertness. Despite its widespread prevalence, all prior studies examining drivers' strategies to combat fatigue and methods to alleviate sleepiness were conducted with participants without OSA, according to Professor Ashleigh Filtness, lead researcher from Loughborough University's Transport Safety Research Center.

The study involved 21 drivers with OSA using continuous positive airway pressure (CPAP) treatment, the most prevalent therapy for OSA, which involves a mask to keep the airway open during sleep. Participants underwent driving simulator sessions following a restricted sleep of four hours, a duration considered representative of CPAP treatment compliance.

Researchers evaluated the impact of varying caffeine amounts, nap durations, and caffeine naps on alertness and driving performance. The findings, published in Scientific Reports, revealed that two cups of coffee significantly enhanced alertness and reduced driving errors compared to one. Extending the nap from 15 to 30 minutes did not yield additional benefits, and modest improvements were observed when a nap was combined with two coffees.

Filtness suggested that higher caffeine consumption among OSA drivers may explain why two coffees proved most advantageous. Although the study found two coffees yielded the greatest alertness improvement, the researchers still recommended taking a 15-minute nap if feasible and safe, as it provided some benefit for certain individuals.

However, all countermeasures are temporary and cannot substitute for adequate sleep before driving. The researchers also observed that participants exhibited impaired driving after just four hours of sleep, underscoring that CPAP treatment compliance does not equate to having sufficient sleep to drive safely. Filtness emphasized that while people with treated OSA can drive safely when alert, they should prioritize obtaining as much sleep as possible with CPAP and avoid driving if necessary.

To disseminate the findings, the researchers have created an animated video and infographic to guide drivers with OSA on what to do if they become drowsy while driving. The Loughborough researchers plan to conduct further studies on napping in vehicles to explore how optimal restorative sleep can be achieved during breaks.