A sleep study, formally known as a polysomnogram (PSG), is a non-invasive diagnostic test that records various physiological functions while you sleep, including brain waves, eye movements, heart rhythm, breathing patterns, and muscle activity. This test identifies disorders like sleep apnea, narcolepsy, or restless legs syndrome. Proper preparation is necessary to prevent external factors from skewing the results and ensure the diagnostic data accurately captures your natural, untreated sleep state.
Dietary and Behavioral Restrictions
Manage your ingestion and daily routine for the 24 hours leading up to the study to avoid altering your sleep drive or neurological activity. The primary restriction involves caffeine, a central nervous system stimulant that can delay sleep onset or disrupt sleep stages. Completely stop consuming all sources of caffeine, including coffee, tea, cola, and hidden sources like chocolate, for at least 12 to 24 hours before your scheduled arrival time.
Alcohol must be avoided entirely for the full 24 hours before the test, as it fragments sleep and suppresses the important rapid eye movement (REM) stage. Similarly, nicotine products, including cigarettes and vaping devices, contain stimulants that interfere with sleep onset and maintenance; centers recommend cessation or strict restriction. Avoiding a nap on the day of the study is also important to ensure a sufficient homeostatic sleep drive, which helps you fall asleep more easily in the unfamiliar lab environment.
Strenuous exercise, particularly a high-intensity workout close to bedtime, can raise your core body temperature and release alerting hormones that may delay sleep onset. Avoid intense physical exertion in the late afternoon or evening before your study; light activity is acceptable. Eat dinner as usual before arriving at the center, but avoid excessively heavy or spicy meals that might cause gastrointestinal discomfort or heartburn.
Specific Guidance on Medications
Addressing prescription and over-the-counter (OTC) medications is important, as many common drugs directly impact the physiological data collected during a sleep study. Never stop taking a prescribed medication on your own, even if it is a known sleep aid, stimulant, or psychoactive drug. Abrupt cessation can be medically unsafe and can invalidate the study by causing an artificial withdrawal effect on your sleep.
Compile a list of every medication and supplement you currently take, including dosages and the exact times you take them. Discuss this list with the referring sleep physician, who will provide personalized instructions on whether to continue, adjust, or temporarily pause any specific drug. Some medications may be temporarily paused days or weeks before a Multiple Sleep Latency Test (MSLT) to assess baseline sleepiness, but this is always under direct medical supervision.
For routine medications, take them as you normally would, including any evening doses, unless explicitly told otherwise. This allows the study to capture data under your current medication regimen. Bring all necessary prescription bottles with you to the sleep center, especially for any doses you need to take during the night or immediately upon waking.
Physical Preparation and Logistics
The day of your sleep study requires preparation to ensure the monitoring sensors can adhere properly and function without interference. You must shower and wash your hair thoroughly on the day of the study using only shampoo, avoiding conditioners, oils, hair sprays, or gels. These products leave a residue that can break the seal between your skin or scalp and the electrodes, leading to poor signal quality.
Avoid applying lotions, creams, makeup, or moisturizers to your face, neck, chest, or legs, as the adhesive used to attach sensors requires clean, dry skin. Remove all nail polish or artificial nails from at least one index finger, as the pulse oximeter device that measures blood oxygen saturation is typically clipped onto a bare fingertip.
For the overnight stay, pack comfortable, loose-fitting, two-piece pajamas, as technicians need access to your torso and legs to attach monitoring bands and sensors. Confirm the exact location and time of your appointment. You should also bring:
- Your standard overnight toiletries.
- A change of clothes for the morning.
- Any non-stimulating reading material to help you relax before lights out.
- Your insurance card and photo identification.
- Any sleep diaries or questionnaires the clinic may have provided.