Drivers with obstructive sleep apnea (OSA) who become sleepy behind the wheel may benefit from two coffees followed by a 15-minute nap, according to new research from Loughborough University.
The study examined whether commonly recommended measures for drowsy driving work equally well for people with OSA, a condition that causes repeated interruptions to breathing during sleep.
Two coffees showed the biggest benefit
Researchers studied 21 drivers with OSA who were receiving continuous positive airway pressure (CPAP) treatment.
Participants completed driving simulator sessions after being restricted to four hours of sleep. Researchers compared different amounts of caffeine, different nap lengths and the combination commonly known as a “caffeine nap”.
The study found that two coffees significantly improved alertness and reduced driving errors compared with one coffee. Adding a nap to two coffees produced modest additional improvements.
A 15-minute nap can still help
Researchers found no additional benefit from extending the nap from 15 to 30 minutes.
They continue to recommend a 15-minute nap when it is safe and practical, as some participants showed a benefit from taking one.
Their practical advice is to pull over safely, drink two coffees and then take a 15-minute nap. If time is limited, drivers can have two coffees and skip the nap.
Four hours of sleep may not be enough
The researchers also found signs of impaired driving after participants had only four hours of sleep.
They stressed that being compliant with CPAP treatment does not necessarily mean a person has had enough sleep to drive safely.
The researchers said all measures to temporarily reduce sleepiness are limited and cannot replace adequate sleep before driving.
The findings have been published in Scientific Reports and researchers hope the work will help improve practical road-safety advice for people living with OSA.