Multiple sleep latency test (MSLT)
During the MSLT, you are given the opportunity to have four or five naps during the course of one day, with the aim of falling asleep.
For each nap you lie in a quiet, darkened room in a sleep centre. You are asked to close your eyes, lie quietly and try to fall asleep. Sensors are placed on your head, face and chin which monitor your sleep stage. They measure whether you are awake or asleep and whether you are in light, deep or dream sleep.
The time taken to drop off is measured during each nap and an average time recorded. The time taken for you to begin dreaming is also measured. This can help to diagnose certain sleep disorders, such as narcolepsy, and assess whether your treatment is working.
Maintenance of wakefulness test (MWT)
This is the opposite of the MSLT. Instead of trying to fall asleep, the aim is to try and stay awake.
For the MWT, the task is to stay awake for 40 minutes on four separate occasions during the day at two-hourly intervals.
During each challenge to stay awake, the room is dimly lit and you are asked to sit in a bed propped up against a cushion, with instructions to try and stay awake for as long as possible. Sensors are placed on your head, face and chin which monitor your sleep stage (as for the MSLT).
The length of time you stay awake during each challenge is measured and an average time recorded. This can help to measure your alertness for a particular job or task.
OSLER Test
The Oxford Sleep Resistance Test, or OSLER test, can be used to screen for excessive daytime sleepiness.
It measures the likelihood of falling asleep when doing a boring task in a dimly lit, quiet sleep centre room. You are given three or four opportunities to complete the task throughout the day.
The task is to press a button on a small handheld device as quickly as possible in response to a flashing light. The light flashes every three seconds for a total of 40 minutes.
You may be so sleepy that you do not respond to all of the flashes. If seven consecutive light flashes are missed you will probably be asleep, so the test is stopped. The time taken to fall asleep is recorded for each attempt at the test.
