The Night Before Your Sleep Study: What NOT to Do
The night before your sleep study shapes how well the recording captures a typical night of sleep. Small habits, such as an afternoon coffee, a glass of wine, a long nap, or hair gel, can blur the data your sleep specialist needs. This guide covers what to avoid before a sleep study, what to do instead, and what to tell the technologist if something goes differently than planned.
This content was reviewed by Dmitriy Kolesnik, MD, Sleep Medicine Specialist at Vector Sleep Diagnostic Center in Queens, NY. Vector has served patients in Rego Park since 2005. Your own center’s written instructions always come first, so use this guide alongside them.
The Night Before Your Sleep Study: Quick Checklist
A sleep study records brain waves, breathing, oxygen levels, heart rhythm, and leg movement during a normal night. The checklist below lists what helps and what to skip. The sections after it explain the reason behind each item.
| Do | Do not |
|---|---|
| Eat a normal dinner | Drink coffee, tea, soda, or energy drinks after lunch |
| Wash your hair and let it air dry | Apply gel, mousse, oils, or hairspray |
| Take prescription medications on your normal schedule | Drink alcohol |
| Remove nail polish from at least two fingers | Take a long afternoon nap |
| Pack two piece sleepwear | Wear one piece pajamas or back tie gowns |
Caffeine Before a Sleep Study: Set the Cutoff Early
Caffeine has a half life of roughly five hours in healthy adults, and the number varies from person to person. An afternoon coffee can still be active at bedtime. Caffeine can lengthen the time it takes to fall asleep, reduce deep sleep, and add awakenings, and each of those changes the picture a sleep study is trying to record. Sleep centers commonly ask patients to stop caffeine by early afternoon on study day, so check the instructions you were given.
Which drinks and products count
- Coffee, tea, and energy drinks
- Sodas that contain caffeine
- Pre workout supplements
- Dark chocolate in larger amounts
- Some pain relievers and weight loss products, so read the label
Alcohol the Night Before Your Sleep Study
Alcohol is a sedative. It can help you drop off faster, but it fragments the second half of the night and can worsen breathing events during sleep. A study recorded after drinking can make sleep apnea look more severe than it is, or can hide a real diagnosis behind an unusual sleep pattern. Skip alcohol on study day. If you normally have an evening drink, tell the technologist so the change from your routine is written down.
Naps and Your Sleep Study Day Schedule
Most patients are asked to avoid daytime naps before an overnight sleep study. A long nap lowers sleep pressure at bedtime, which can make it harder to fall asleep in the lab and cut the total sleep time recorded. A recording with too little sleep may not answer the clinical question, and that can mean repeat testing.
If severe daytime sleepiness makes you nap, ask your sleep physician for specific instructions before the day of the study. Some tests, including the Multiple Sleep Latency Test, ask for a set sleep pattern the night before. If a poor night is part of your story, a sleep diary gives your physician a clearer view of your usual schedule.
Hair, Skin, and Nails: Preparing for the Sleep Study Sensors
Hair products and electrode contact
Polysomnography uses scalp electrodes to record brain waves. Gels, mousses, oils, dry shampoo, hairspray, and leave in conditioner reduce contact between your skin and the electrode, which adds electrical noise to the brain wave channels. Wash your hair clean and let it air dry. Skip styling products until the study is over.
Nail polish and the pulse oximeter
A pulse oximeter clips onto a fingertip and measures oxygen saturation with red and infrared light shone through the nail. Dark polish, glitter, and acrylic nails can block that signal. Remove polish from at least the index and middle fingers of one hand before you arrive.
Lotion and makeup
Many centers ask patients to skip heavy lotion and oil based makeup on the face and body, because oils can keep sensors from sticking through the night. Arrive with clean, dry skin unless your center tells you otherwise.
What to Pack for Your Overnight Sleep Study
Treat the night like a short hotel stay. Familiar items help your body settle, and that helps the study capture normal sleep.
- Two piece sleepwear that is comfortable and easy to move in
- Your own pillow, if you sleep better with it
- A book or magazine for quiet time before lights out
- A list of your medications, and any over the counter sleep aids you use
- Your phone charger, set aside for the evening
- A toothbrush and a change of clothes for the morning
If You Slip Up the Night Before a Sleep Study, Tell the Technologist
If you drank coffee out of habit, used hair product, or fell asleep on the couch at 5 p.m., do not skip the appointment. Tell the technologist at check in. Each variable goes on your study record so the interpreting physician can account for it. A documented variable is far easier to work with than an unexplained finding when the study is read.
Can’t Fall Asleep at the Sleep Study?
Many patients are surprised by how much they sleep in the lab. A familiar pillow, your normal bedtime routine, and a few pages of a book all help. A partial night can still carry useful information. If insomnia is your main complaint and you expect sleeplessness to affect the study, talk to your physician before the appointment about whether a structured insomnia evaluation belongs in your workup.
Traveling to Your Sleep Study in Queens
Patients who live more than an hour away sometimes arrive late, hungry, or tense from traffic, and none of that helps at lights out. Plan to arrive for check in on time, eat a normal dinner before you leave home, and allow extra time for traffic and parking. Technologists need time to place sensors before lights out, so a late arrival can shorten an otherwise normal study.
Choosing between settings? Our guides on hospital sleep labs versus independent centers, the cost of a home sleep test, and the best time to schedule a sleep study can help. Once your study is done, here is what happens with your results, and how accurate a sleep study is. For general background, see the patient pages from the American Academy of Sleep Medicine and the National Heart, Lung, and Blood Institute.
Frequently Asked Questions About the Night Before a Sleep Study
Can I drink caffeine in the morning before my sleep study?
One morning cup is usually fine for most people, but sleep centers commonly ask patients to stop caffeine by early afternoon on study day. If you are sensitive to caffeine, skip it entirely and follow the written instructions your center gave you.
What if I accidentally drank alcohol before my sleep study?
Tell the technologist when you arrive. Depending on how much you had, your sleep physician may still read the study with a note on your record, or may ask you to reschedule.
Why can’t I nap before my sleep study?
A nap lowers your sleep pressure at night. That can make it harder to fall asleep in the lab, shorten the recording, and reduce what the study can show.
Can I wear makeup to my sleep study?
Light makeup is usually fine, but heavy foundation, oil based products, and eye makeup can interfere with the sensors placed on your forehead and around your eyes. Arrive with a clean face if your center asks for it.
Should I take my usual medications the night before a sleep study?
Take prescription medications on your normal schedule unless your sleep physician has told you otherwise, and bring a list of everything you take. Do not stop a prescribed medicine on your own.
Should I bring sleep aids I do not have a prescription for?
Bring them and tell the technologist. Over the counter sleep aids, melatonin, and antihistamines can change how you sleep, so they belong on your study record.
What should I do if I cannot fall asleep during the study?
Stay relaxed and tell the technologist if you need anything. Many people sleep more than they expect in the lab, and even a partial night can give your physician useful information.
When to Talk to a Sleep Specialist
If you have questions about preparing for your study, or you are ready to find out why you are not sleeping well, Vector Sleep Diagnostic Center in Rego Park, Queens, can help. Reach the team at vectorsleep@gmail.com or call (718) 830-2800.
