Is the 2 h recommended maximum driving time appropriate for both

healthy older and treated obstructive sleep apnoea drivers?

A.J. Filtness, L.A. ReynerESRS 2010 - Occupation and environment

Thursday, 16 September 2010

2

Overview

BackgroundMethod

Driving simulatorResults

Successful completion Safe driving time

Conclusion

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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.

Driver fatigue recommendationThe 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 91Driving 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).

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UK Highway Code

The Highway code - Fitness to drive: rule 91Driving 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).

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6

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

Method – Driving Simulator

38 participants male, age 50 – 75y 19 OSA patients, ave 8.6y CPAP 19 healthy control participantsDual carriageway2 h afternoon drive

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Repeat measure counterbalanced design Normal nights sleep (8 h) Sleep restriction to (5 h)

Additional study night OSA participants without CPAP (n=11)

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Measures

Driving Incidents: car wheels crossed a lane demarcation line

Incidents were classified as “sleep related” or “non sleep related”

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Results

Percent of drives successfully completed Average time to first incident

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Results – Percent of Successful Completion

Normal sleep Sleep restriction0

102030405060708090

100

Control

OSA with CPAP

OSA without CPAP

Perc

ent

11

Results – Percent of Successful Completion

Normal sleep Sleep restriction0

102030405060708090

100

Control

OSA with CPAP

OSA without CPAP

Perc

ent

12

Results – Percent of Successful Completion

Normal sleep Sleep restriction0

102030405060708090

100

Control

OSA with CPAP

OSA without CPAP

Perc

ent

13

Results – Safe Driving Time

Normal Sleep Sleep Restriction0

20

40

60

80

100

120

Control

OSA with CPAP

OSA without CPAP

Tim

e (m

in) t

o fir

st in

cide

nt

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Results – Safe Driving Time

0

10

20

30

40

50

60

Control

OSA with CPAP

OSA without CPAP

Tim

e (m

in) t

o fir

st in

cide

nt

Condition [F(1,36) = 9.24, p<0.05]Condition, group interaction[F(1,36) = 4.16, p<0.05]

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Results – Safe Driving Time

0

10

20

30

40

50

60

Control

OSA with CPAP

OSA without CPAP

Tim

e (m

in) t

o fir

st in

cide

nt

OSA. Condition [F(2,20) = 8.8, p<0.05]

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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.

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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.

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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.

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Acknowledgements

Prof. Jim Horne,Loughborough UniversityDr Andrew Hall and Dr Chris Hanning, Leicester General Hospital

Thank you for listening