Is the 2 h recommended maximum driving time appropriate for both healthy older and treated obstructive sleep apnoea drivers? A.J. Filtness, L.A. Reyner ESRS Occupation and environment Thursday, 16 September 2010

Overview Background Method  Driving simulator Results  Successful completion  Safe driving time Conclusion 2

Background Obstructive Sleep Apnoea (OSA) Group 1 licence holders (car/ motorcycle) diagnosed with sleep apnoea must stop driving until the symptoms have been controlled and confirmed by medical opinion. 3 Driver fatigue recommendation The UK Department for Transport produces the Highway code. A list of rules and recommendations for road users.

UK Highway Code The Highway code - Fitness to drive: rule 91 Driving when you are tired greatly increases your risk of collision. To minimise this risk  make sure you are fit to drive. Do not begin a journey if you are tired. Get a good night’s sleep before embarking on a long journey  avoid undertaking long journeys between midnight and 6 am, when natural alertness is at a minimum  plan your journey to take sufficient breaks. A minimum break of at least 15 minutes after every two hours of driving is recommended  if you feel at all sleepy, stop in a safe place. Do not stop on the hard shoulder of a motorway  the most effective ways to counter sleepiness are to drink, for example, two cups of caffeinated coffee and to take a short nap (at least 15 minutes). 4

UK Highway Code The Highway code - Fitness to drive: rule 91 Driving when you are tired greatly increases your risk of collision. To minimise this risk  make sure you are fit to drive. Do not begin a journey if you are tired. Get a good night’s sleep before embarking on a long journey  avoid undertaking long journeys between midnight and 6 am, when natural alertness is at a minimum  plan your journey to take sufficient breaks. A minimum break of at least 15 minutes after every two hours of driving is recommended  if you feel at all sleepy, stop in a safe place. Do not stop on the hard shoulder of a motorway  the most effective ways to counter sleepiness are to drink, for example, two cups of caffeinated coffee and to take a short nap (at least 15 minutes). 5

Aim To assess the appropriateness of this recommendation for OSA patients treated with CPAP, compared with healthy controls of a similar age.  Following a normal night’s sleep (OSA with CPAP)  Under sleep restriction conditions (5h) (OSA with CPAP)  Following normal sleep length, OSA without CPAP 6

Method – Driving Simulator 38 participants male, age 50 – 75y  19 OSA patients, ave 8.6y CPAP  19 healthy control participants Dual carriageway 2 h afternoon drive 7 Repeat measure counterbalanced design  Normal nights sleep (8 h)  Sleep restriction to (5 h) Additional study night  OSA participants without CPAP (n=11)

Measures  Driving Incidents: car wheels crossed a lane demarcation line  Incidents were classified as “sleep related” or “non sleep related” 8

Results  Percent of drives successfully completed  Average time to first incident 9

Results – Percent of Successful Completion 10

Results – Percent of Successful Completion 11

Results – Percent of Successful Completion 12

Results – Safe Driving Time 13

Results – Safe Driving Time 14 Condition [F(1,36) = 9.24, p<0.05] Condition, group interaction [F(1,36) = 4.16, p<0.05]

Results – Safe Driving Time 15 OSA. Condition [F(2,20) = 8.8, p<0.05]

Summary of findings  UK Highway Code recommends to break from driving every 2 hours to avoid driver fatigue.  52.6% of all 2h drives were completed successfully.  The drive presented was a ‘worst case scenario’.  Sleep restriction significantly affected both control and OSA participants.  OSA participants were more affected by sleep restriction than controls. 16

Implications  Recommend older drivers take a break from driving every 90 minutes, more often if sleep restricted.  Older drivers do not cause a high percent of road traffic incidents so may break from driving every 2 hours for reasons other than sleepiness.  Education of OSA patients: non-compliance with CPAP can significantly impair driving performance and vulnerability to sleep restriction. 17

Conclusion  It is important to get a full night’s sleep prior to completing a long motorway drive.  It is important for OSA drivers to be compliant with CPAP treatment every night. 18

Acknowledgements 19 Prof. Jim Horne, Loughborough University Dr Andrew Hall and Dr Chris Hanning, Leicester General Hospital Thank you for listening