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Most Frequently Asked Questions

Lofta At-Home Sleep Test

• What is WatchPAT?

  WatchPAT is an FDA-approved portable diagnostic device that uses the most innovative technology to ensure the accurate screening, detection, and the follow-up treatment of sleep apnea. Its ease of use is unparalleled in the marketplace and it is greatly complemented by the fact that WatchPAT testing is done in the comfort of your own bedroom, an environment that best reflects the pattern of your sleep habits. That fact alone may prove to be a lifeline for the millions of undiagnosed individuals who are unwilling to spend the night away from home in a sleep lab. And for those patients who are waiting for a polysomnography (PSG) but can’t be tested due to sleep center backlog, WatchPAT offers an immediate solution. WatchPAT has been validated against PSG.

• How accurate is WatchPAT in comparison to a full sleep lab Polysomnography study?

  Numerous validations studies demonstrated a high degree of correlation in RDI (Respiratory Disturbance Index) and AHI (Apnea-Hypopnea Index) between same-setting WatchPAT and polysomnography (PSG) sleep studies with R= 0.85- 0.96. Moreover, the RDI and AHI scores are highly reproducible, showing correlation between at-home and in-laboratory sleep studies.

• How does WatchPAT detect apnea, hypopnea, and respiratory effort related arousal (RERA) events?

  WatchPAT utilizes Peripheral Arterial Tone (PAT), a physiological signal that mirrors changes in the autonomic nervous system caused by respiratory disturbances during sleep. The automatic algorithm of WatchPAT analyzes the PAT signal amplitude along with heart rate and oxygen saturation to identify respiratory events. Using specific signal patterns, the algorithm provides the two critical indices—AHI and RDI.

• How does WatchPAT detect rapid eye movement (REM)?

  Rapid eye movement (REM) sleep is associated with considerable attenuation of the PAT signal and physiology coupled with specific variations in the PAT amplitude and rate. Based on this specific variability in the PAT and pulse rate signals, REM sleep stage is differentiated from non-REM sleep. In addition, it is differentiated from the wake state by WatchPAT’s advanced actigraphy algorithms.

• How does WatchPAT detect sleep architecture?

  WatchPAT’s sleep/wake detection is based on data recorded by the built-in actigraph. The propriety software's automatic actigraph algorithm discriminates between sleep and wake states in normal subjects and those with obstructive sleep apnea (OSA). This algorithm makes WatchPAT superior to all other actigraph devices—most of them fail when used with OSA subjects. WatchPAT's sleep/wake algorithm has been validated and published in peer-reviewed journals. The results show close agreement between actigraphy and PSG in determining sleep efficiency, total sleep time, and sleep latency (agreement 86% in normal subjects, 86%-mild OSA, 84%-moderate OSA, 80% severe OSA). Hedner J, Pillar G, Pittman DS, Zou D, Grote L, White D. A Novel adaptive wrist actigraphy algorithm for sleep-wake assessment in sleep apnea patients. Sleep, 2004, 27(8):1560-6.

• How does WatchPAT differentiate between light and deep sleep?

  WatchPAT’s zzzPAT algorithm is based on 14 features extracted from two time series of PAT amplitudes and inter-pulse periods (IPP). Those features are then further processed to yield a prediction function that determines the likelihood of detecting a deep-sleep epoch stage during Non-REM sleep periods. Ma'ayan Bresler, Koby Sheffy, Giora Pillar, Meir Preiszler, Sarah Herscovici, Differentiating between light and deep sleep stages using an Ambulatory Device Based on Peripheral Arterial Tonometry. Physiol Meas. 2008; 29(5): 571-584.

• What is the advantage to using sleep time vs study time when correlating AHI and RDI?

  One of the biggest problems with the vast majority of ambulatory sleep apnea devices is the lack of “real sleep” monitoring—the other devices record both sleep and awake time. These devices then provide “total study time,” in which case the respiratory disturbances index (RDI) is calculated by dividing the total number of respiratory events by a substantially longer time period, thus providing a lower RDI (or AHI) than the actual one—which is the time asleep.

• Can the raw data of the WatchPAT sleep study be edited?

  All raw data provided by WatchPAT’s zzzPAT software can be edited and over-written by the physician. While we do not suggest that this be done, because the accuracy of the algorithms has been proven, the physician has free reign over all collected data.

• What is the PAT signal?

  PAT technology is a non-invasive window to the cardiovascular system and autonomic nervous system. The Peripheral Arterial Tone (PAT) signal is a proprietary technology used for non-invasively measuring arterial tone changes in peripheral arterial beds. The PAT Signal is measured from the fingertip by recording finger arterial pulsatile volume changes.

• How long does the test take?

  The amount of time people sleep varies from person to person. The WatchPAT is put on when you go to bed. It is taken off when you wake in the morning. The WatchPAT will record your particular sleep cycles.

• What is sleep apnea?

  Derived from the Greek word for “lack of breath,” sleep apnea is a serious, potentially life-threatening sleep-related breathing disorder that is often linked with loud, heavy snorers. Sleep apnea can be the result of an abnormality in the respiratory pacemaker in the brain (central sleep apnea) or, more commonly, it may be triggered by an obstruction in the upper airway (obstructive sleep apnea), which decreases the amount of inhaled air, collapsing the tissue in the back of the throat, and disrupting sleep. An episode of partial airway closing is called a sleep hypopnea. Individuals with OSA experience repetitive episodes of obstruction of the upper airway during sleep, lasting anywhere from 30 seconds up to two minutes. With no air flowing into the lungs, oxygen levels drop and carbon dioxide levels rise in the blood. The reduction in oxygen and increased carbon dioxide alert the brain to resume breathing and cause an arousal. Finally, the patient awakens with a jolt and resumes breathing, and quickly falls back to sleep—and resumes the loud snoring. Blood pressure spikes up during the arousal, sometimes by as much as 30 mm Hg systolic, the top number in your hypertension reading. As the person goes back to sleep, typically unaware of having awakened, the throat muscles relax once again, the airway closes, and the sleep apnea pattern is repeated again. And again. And again. These subsequent and frequent arousals, although necessary for breathing to restart, prevent you from getting enough restorative, deep sleep.

• How many people develop sleep apnea?

  As many as 4% of American men, 2% of all women, 3% of children, and as many as 20% to 30% of adults older than 60 develop sleep apnea, making it as common as diabetes and asthma. The Greek philosopher Homer, who once described sleep as “the brother of death” might have said the same about apnea had he known that it quadruples the risk of heart attack and triples the risk of stroke.

• What are the symptoms of sleep apnea?

  Sleep apnea has one major tip-off: Loud and harsh snoring interspersed with long pauses when breathing stops for extended periods. This is followed by a violent snort, gasp, or moan when the brain signals a need for more oxygen. It’s these constant disruptions throughout the night, with its reduced levels of oxygen in the blood and increased levels of adrenaline from the autonomic nervous system, that are thought to cause unnatural surges in blood pressure experienced by people with sleep apnea. Not everyone who snores has sleep apnea, but almost everyone who has sleep apnea snores. Common symptoms of sleep apnea include: Awakening due to gasping or choking Restless sleep Memory impairment Morning headaches Morning sore throat or dry mouth Frequent awakening to urinate Memory impairment Erectile dysfunction.

• What causes sleep apnea?

  Sleep apnea is caused by abnormal closure of the airway during sleep. The cause of this may be multi-factorial. Sleep researchers used to think that sleep apnea occurred in obese patients due to their upper airway closing during sleep because of the fat that surrounded the airway, narrowing it and making it more collapsible. However, it’s much more complicated than that. While it is true that obesity is a major risk factor for sleep apnea, there are many obese people who don’t have sleep apnea, and there are also non-obese people who do have it. Clearly, sleep apnea is more than just upper airway closure related to obesity. Sleep experts are now looking into neuromuscular control issues as a possible cause.

• How does sleep apnea affect hypertension?

  Sleep apnea results in periods of higher blood pressure, or hypertension, as the heart tries to counter the build-up of carbon dioxide by pumping harder. Increases in arterial pressures of 30 mm Hg or more are not uncommon. By contrast, adults who do not have sleep apnea will typically experience nighttime blood pressure drops of about 10%.

• What is the link between apnea and heart arrhythmias?

  Atrial fibrillation (AF), the most common arrhythmia (abnormal rhythm), is a rapid-fire beating of the heart’s upper chambers, called the atria, which then leads to an irregular and often rapid beating of the lower chambers, called the ventricles. While AF may cause bothersome symptoms for some, other people diagnosed with AF experience no symptoms whatsoever. Unlike ventricular arrhythmias—the rapid and controlled/uncontrolled beating that originates in the heart’s lower chambers (ventricles) that can cause sudden death—AF usually poses no immediate danger. However, for some older patients, and those with underlying heart disease, AF does present a risk for stroke if left untreated. While it’s not always possible—or even necessary—to restore the heart to normal rhythm, some physicians believe it’s logical to restore the normal tempo of a healthy heart.

• What effect does sleep apnea have on memory?

  Many people develop memory deficits due to sleep apnea and they will often complain of daily forgetfulness, losing their keys, forgetting phone numbers, or forgetting to complete daily tasks. The good news is that most individuals with obstructive sleep apnea may improve their memory by using Continuous Positive Air Pressure, also known as CPAP.

• Is sleep apnea linked to depression?

  Depression is a very common ailment in this country and there’s a very strong link between the two ailments. People with sleep apnea often complain of fatigue, lack of energy and poor sleep, all of which are hallmarks of depression. However, sleep researchers don’t know if the depression is due to sleep deprivation, or if it’s a specific manifestation of the sleep apnea itself. What we do know is that when sleep apnea is effectively treated, the depression often gets better.

• Does sleep apnea adversely affect marriages?

  Sleep researchers know that sleep apnea can cause problems in marriages. Loud snoring will certainly make it difficult for anyone to sleep, and this includes even the most loving and understanding of partners. Moreover, for many bed partners forced to sleep with someone who snores, it’s often a long and troubled sleep as they lay in bed listening to their partner’s long periods of not breathing, followed by the violent gasping and struggle for air. Using a CPAP device on a nightly basis not only eliminates sleep apnea but in almost all cases fully eliminates snoring.

• If you haven’t had sleep apnea as a young adult, why does it suddenly show up when you’re 30, 40, or 50?

  That’s a complicated question with a complicated answer. With most people, it gets back to being overweight or obese. Leading sleep experts believe that if a person gains weight, that’s what leads to their sleep apnea. Seasonal allergies or sinus problems that people may not have had before can suddenly cause sleep apnea. For women, menopause seems to play a significant role in sleep apnea. It’s quite common for older menopausal women to develop some fat in their necks and that obstructs breathing. During the post-menopausal years, sleep apnea is almost as common for women as it is for men, perhaps due to both the increase in testosterone and the decrease in progesterone and estrogen that occur in menopause.

• Do I Have Sleep Apnea?

  You may, if you are overweight or obese or if you snore loudly. High blood pressure, decreased airway size, and a family history of apnea are also risk factors. Sleep apnea is a serious condition that requires prompt attention to avoid potentially life-threatening complications. The good news is that a host of effective therapies for sleep apnea—including lifestyle and medical—can control sleep apnea and help you avoid such potentially devastating complications as heart attack or stroke. Take the Lofta Sleep Apnea Quick Screen on this site to see if you are at risk.

• What is the Apnea-Hypopnea Index?

  In severe sleep apnea cases, people are briefly awakened hundreds of times every night due to oxygen deprivation (imagine someone sitting at your bedside, tapping you on the shoulder every minute or so to awaken you), leading to poor sleep and extreme fatigue during the day. The number of these episodes per hour of sleep—as measured with an at-home WatchPAT sleep study or a sleep-laboratory study—is called the Apnea-Hypopnea index, or the AHI. This index specifically calculates sleep apnea severity based on the total number of complete cessations (apnea) and partial obstructions (hypopneas) of breathing per hour of sleep. Some individuals have 50 or more episodes per hour; most sleep experts use a cutoff of 10 events or more per hour before considering treatment with a continuous positive airway pressure (CPAP) device or some other sleep apnea therapy.