During a Polysomnogram (PSG)

  • Sensors called electrodes are placed on your scalp, face, chest, and limbs. While you sleep, these sensors record your brain activity, eye movements, heart rate and rhythm.
  • You will also have a pulse oximetry which records the amount of oxygen in your blood.
  • Elastic belts are placed around your chest and abdomen. They measure chest movements and the strength and duration of inhaled and exhaled breaths.
  • At the end of the PSG, the technician removes the sensors. If you're further testing such as an MSLT or MWT some of the sensors might be left on for that test.

What to expect during a sleep study? Sleep studies are painless. A sleep technician will make the room comfortable for you. Most of your contact at the sleep center will be with the sleep technicians.

During a Multiple Sleep Latency Test

  • The MSLT is a daytime sleep study that is done after a PSG. The MSLT includes 5 nap periods.
  • This test involves sensors placed on your scalp, face, and chin. These sensors record brain activity and eye movements. They show various stages of sleep and how long it takes you to fall asleep.
  • 1.5-3 hours after you wake from the PSG, you're asked to relax and try to fall asleep in a dark, quiet room. The test is repeated five times throughout the day.
  • You get 2-hour breaks between tests. You need to stay awake during the breaks. During these breaks, you can read, watch television, etc.
  • The MSLT records whether you fall asleep during the test and what types and stages of sleep you have.

During a Maintenance of Wakefulness Test

  • This sleep study can be done the day after a PSG or just by itself. Sensors on your scalp, face, and chin are used to measure when you're awake and asleep.
  • The MWT consists of four trials performed at two-hour intervals, with the first trial beginning about 1.5 to 3 hours after the patient’s usual wake-up time. This usually equates to a first trial starting at 9:00 a.m. or 10:00 a.m.
  • You sit quietly in a chair in a comfortable position and look straight ahead. Then you simply try to stay awake for a period of time.
  • There usually are 2-hour breaks between trials. During these breaks, you can read, watch television, etc.
  • If you're being tested as a requirement for a transportation- or safety-related job, you may need a drug-screening test before an MWT.