The OSLER examination is typically used to determine whether you can continue driving despite having a condition that causes daytime sleepiness, such as sleep apnoea or narcolepsy.
OSLER examination
The OSLER examination is a behaviour-based wakefulness assessment. It measures your ability to stay awake in monotonous situations
Check the patient instructions you received in advance for specific preparation guidelines. For the examination to be valid, it is important that you sleep normally the night before—preferably at least 6 hours.
In the OSLER examination, you sit quietly in a dimly lit room and try to stay awake for 40 minutes. You look at a device in front of you where a small light flashes every three seconds. Your task is to press a button on a handheld device each time the light flashes. There are three 40-minute test sessions during the day.
A nurse monitors your performance via video from another room. If you fail to press the button for seven consecutive light flashes, it is considered that you have fallen asleep and the test ends.
A normal examination result means that pressing the button helps you stay awake and you do not fall asleep during the test sessions.
The examination does not require follow-up and does not impose any restrictions on normal daily activities.
The physician who referred you for the examination will inform you of the results and the next steps in your treatment. If you do not have a scheduled appointment or call time, please contact your care unit.
The examination is painless and involves no risks.
Updated 7.11.2025