The Downward Slope: Your Metabolism Working Overtime
The Downward Slope is a sign that your metabolism is working overtime. Did you have a late meal, a late workout, or a glass of wine before bed? If your RHR starts high and reaches its lowest point right before you wake up, you may start the day feeling groggy.
If you regularly see this downward slope, it may be wise to stop and reassess your evening routine. For example, if you normally work out late at night, exercising 12 hours earlier can result in positive changes.
Cpap Therapy Can Prevent The Damage That Sleep Apnea Does To The Heart
Fortunately, there is a solution. Treatment of sleep apnea earlier in life can prevent this cascade, and halt the series of insults that lead to heart failure and death, says Redline. A research team based in Ireland followed 168 patients over several years after they started continuous positive airway pressure therapy. The team found that the development of new cases of heart disease reached 14 percent in the group of people who did not use CPAP, compared to 5 percent in a group that did ^10. The fact that the treatment saves lives also strengthens researchers certainty that there is a connection between cardiac-related problems and sleep apnea.
Another research group, this time in Spain, also followed up after an initial sleep study to see if CPAP made a difference in the participants survival. Every year for over a decade, the team checked in on 264 healthy men, 377 male snorers, 403 men with untreated mild-to-moderate obstructive sleep apnea, 235 with untreated severe sleep apnea and 372 men with sleep apnea who used CPAP. After 12 years, the group of men with untreated severe sleep apnea had the worst outlook. More than a third had experienced a non-fatal cardiovascular event such as a heart attack, and about 17 percent had a fatal event . In contrast, the men who used CPAP experienced such events only at about the same rate as the healthy men ^11.
Why Could A Low Heart Rate Be Bad In Some Situations
The heart needs to pump out a certain amount of blood to provide the body with the blood it needs to function. The amount of blood pumped is known as cardiac output and is usually defined as liters per minute. Heart rate of course affects this output. In some patients a low heart rate can lead to a low output and cause symptoms such as dizziness, shortness of breath and fatigue. These symptoms are associated with low output heart failure. In other patients a low heart rate causes no effect whatsoever as the heart simply pumps out more blood with each beat to compensate.
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What You Need To Know About How Sleep Apnea Affects Your Heart
Snoring can keep you awake, ruin your sleep cycle and your daily rhythm, even harm your relationships. But more than being just an annoyance, snoring may bring about life-threatening consequences.If youve ever awakened yourself with a sudden snore or if your partner nudges you awake to get you to turn over its possible you could be affected by sleep apnea, which is associated with high blood pressure, arrhythmia, stroke and heart failure.
Pathophysiological Consequences Of Sleep Apnea Adversely Affect Progression Of Heart Failure
In regards to sleep apnea , both CSA and OSA, is associated with three immediate adverse biological consequences: A) arterial blood gas abnormalities consisting of repetitive episodes of hypoxemia/hypercapnia which occur due to apnea, followed by reoxygenation/hypocapnia associated with recovery from apnea, and B) large negative swings in intrathoracic pressure and C) arousals. These consequences are qualitatively similar for both OSA and CSA, but more pronounced with OSA.
These nocturnal events occurring night after night, eventually adversely affect various cardiovascular functions and structure.1 These adverse effects should be most detrimental in the presence of established left ventricular systolic and diastolic dysfunction and coronary artery disease.
In regards to sympathetic activity which has a profound effect on the natural history of heart failure, multiple studies have shown that both OSA and CSA, independent of HF, are associated with increased sympathetic activity as measured by an increase in both plasma and urinary catecholamines, heart rate variability and muscle sympathetic nerve activity.
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Obstructive Sleep Apnea As A Model Sleep Disorder
Obstructive sleep apnea is a sleep disorder characterized by repetitive cessations of respiratory flow for at least 10s. Typically sleep apnea events last for 3060s. The respiratory cessations are owing to a collapse of the upper airways that are normally kept open during breathing. With the drop of muscular tone during the period of falling asleep in patients with sleep apnea there is a faster drop in muscular tone of the upper airways than the diaphragm and the accessory respiratory muscles. Thus with a continued muscular effort of breathing during sleep, the upper airways collapse when the negative intrathoracic pressure created for inspiration during each breath becomes too strong to keep the upper airways open. Each apnea ends with a central nervous activation , which reconstitutes the regulation of breathing. The arousal is caused by the drop in oxygen and the increase in carbon dioxide during the course of the apnea. These arousals remain below the level of wakefulness and are not noticed by the patient affected by sleep apnea. A patient with sleep apnea may have 600 single apnea events in one night. Not always the upper airway obstruction needs to be complete. A partial obstruction is called hypopnea. A patient suffers from sleep apnea if he has more than five apnea and hypopnea events per hour of sleep. This number is defined as the apnea-hypopnea index .
Sleep Apnea Coronary Artery Disease And Cariovascular Mortality
The association between sleep apnea and coronary artery disease and cardiovascular mortality was considered in a Spanish study of 1,500 patients followed for 10 years, which reported that CPAP therapy reduced cardiac events in patients with OSA. Patients with sleep apnea had an increased risk of fatal myocardial infarction or stroke. Survival of patients treated for sleep apnea approached that of patients without OSA.
In a study of a racially diverse cohort, an association of physician diagnosed sleep apnea with cardiovascular events and survival was identified. Diagnosed sleep apnea was estimated to confer a two-to threefold increase in various cardiovascular outcomes and all-cause mortality.
All-cause mortality data from the Sleep Heart Health Study of more than 6,000 participants showed that progressive worsening of OSA as defined by the apneaâhypopnea index resulted in poorer survival even after accounting for confounding factors . Decreased survival appeared to mostly affect men or patients under age 70.
Sudden death from cardiac causes by time of day
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Activating The Sympathetic Nervous System
Each time a person with sleep apnea stops breathing, the level of oxygen in the blood decreases. As the body becomes deprived of oxygen, specialized cells called chemoreceptors detect these changes and activate the sympathetic nervous system to respond, which is the part of the nervous system responsible for reacting to stressful or dangerous situations. The sympathetic nervous system triggers the body to gasp for air, which sometimes wakes a person out of sleep.
The sympathetic nervous system also responds to a low level of oxygen by constricting blood vessels and increasing heart rate and blood pressure. As the pauses in breath continue throughout the night, repetitive changes in blood pressure may lead to hypertension or make existing hypertension worse.
Impact Of Osa On Mortality And Effect Of Treatment With Cpap
A prospective study11 reported a significantly greater death rate in 37 untreated heart failure patients with OSA than in the 113 patients without OSA. The death rate was significant after controlling for confounding factors. Furthermore, the authors reported no deaths among the 14 heart failure patients with OSA who were treated with CPAP devices, the treatment of choice for OSA. However, n was small and this difference was significant at .07 p value.
In a French study, comparing 50 patients with AHI < 5/hour to 236 patients with AHI 5 hour Damy and colleagues15 reported excess mortality associated with OSA. Furthermore, the authors reported that treatment of OSA with positive airway pressure device was associated with improved survival in 62 patients compare to the 48 untreated patients with AHI 20/hour.
In a study AHI from Japan,12 in patients with HFrEF and moderate to severe OSA , use of a CPAP device was associated with significant reduction in the rate of hospitalization and mortality when compared to 23 untreated OSA patients. The improved survival was only in CPAP adherent patients.
In the only study from US, of several thousand Medicare beneficiaries,4 we reported improved survival , less hospitalization and cost of couple of hundred treated patients compared to several thousand untreated HF patients after accounting for a number of confounders
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Technical Features Of Hrv Measurements
There are some important technical features that affect HRV analysis. In this respect, ECG sampling rate could be critical to the accuracy and reliability of the HRV time series. Two hundred and fifty hertz or higher are recommended, however, given the minor relative errors among various ECG sampling rates, over 100 Hz are acceptable in time-domain, frequency-domain, and non-linear HRV analysis . Concerning the extraction of RR intervals, there is a big variety of algorithms aimed at detecting the R peaks , being the Pan and Tompkins the most well-known one . However, artifacts and ectopic beats are usually present in ECG recordings, which can result in non-normal RR intervals, thus affecting HRV analysis. This issue is addressed by detecting and correcting non-normal beats. The detection of non-normal beats can be performed using different automatic methods: time and morphological approaches, methods based on the morphological transformation, wavelet-based approaches, empirical mode decomposition methods, and neural network approaches . Conversely, deletion, interpolation , and adaptive approaches are used to correct non-normal beats . However, these methods can also cause measurement errors in the HRV signal, which demands more research efforts on the development of correction methods.
Why Might Osa Increase A
The researchers are unable to describe the precise mechanisms that drive the link between OSA and increased risk of A-fib, but senior author Dr. Richard S. Leung, of the University of Toronto in Canada, has some theories:
âGreater endothelial dysfunction, higher propensity to develop pulmonary and systemic hypertension and impaired heart rate responses to autonomic challenges in women with OSA may explain these findings,â he says, âbut further studies are needed to confirm this finding and understand the potential mechanisms.â
The researchers admit that there are some limitations to their study. For example, they did not have data on patientsâ adherence to treatment with continuous positive air pressure, which is the primary therapy for patients with OSA.
What is more, the team was unable to determine whether or not patients were being treated for high blood pressure.
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Sleep Apnea May Cause Weight Gain
While not everyone who is overweight has sleep apnea, people who are obese are more likely to be diagnosed with the disorder, according to the NSF. And if you have sleep apnea, youre also at risk of gaining weight.
Whats behind the obesitysleep apnea link? When you gain weight, fat can accumulate in the neck area and obstruct your breathing, leading to sleep apnea.
Plus, adds Dasgupta, when you dont get enough sleep, your body doesnt produce enough of the appetite-regulating hormone leptin, which helps reduce hunger, says Dasgupta. The lower the levels of leptin, the harder it is to control appetite and lose weight, he explains.
Sleep apnea may also increase your risk for excessive daytime sleepiness, which may decrease your physical activity levels and lead to weight gain. According to the NSF, losing 10 percent of your body weight can make your sleep apnea less severe or even get rid of it completely.
What Causes Sleep Apnea
Obstructive sleep apnea is caused by a blockage of the airway, usually when the soft tissue in the rear of the throat collapses during sleep. Central sleep apnea is usually observed in patients with central nervous system dysfunction, such as following a stroke or in patients with neuromuscular diseases like amyotrophic lateral sclerosis . It is also common in patients with heart failure and other forms of heart, kidney or lung disease.
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How Does Your Heart Rate Change While You Sleep
During sleep, the stimulation of your nervous system is reduced and most of your body processes slow down, says Dr. Lawrence Epstein, associate physician with the division of sleep and circadian disorders at Harvard-affiliated Brigham and Womens Hospital.
Within about five minutes after you drift off to sleep, your heart rate gradually slows to its resting rate as you enter whats known as light sleep. Your body temperature drops and your muscles relax. People typically spend about half the night in light sleep. But during the next phase, deep sleep, your blood pressure falls and your heart rate slows to about 20% to 30% below your resting heart rate.
When you dream, you enter the sleep phase known as REM . Your heart rate can vary quite a bit during REM sleep because it reflects the activity level occurring in your dream. If your dream is scary or involves activity such as running, then your heart rate rises as if you were awake, says Dr. Epstein.
Sleep Apnea And Bradycardia: The Cardiovascular Connection
So whats the connection between sleep apnea and bradycardia? The Mayo Clinic lists obstructive sleep apnea as a potential cause for bradycardia due to its tendency to interrupt your bodys sleep patterns.3 A slow heart rate can mean youre not getting enough oxygen, and failure to get enough oxygen is symptomatic of sleep apnea, a condition that causes you to continually wake up throughout the night because of obstructed breathing.
In a broader sense, bradycardia is a condition affecting the heart, and sleep apnea has a well-known association with heart conditions.45 Numerous studies have been published that support that connection a 2007 study in the European Respiratory Journal stating that considerable evidence is available in support of an independent association between and cardiovascular disease is a good example.6
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Sleep And High Blood Pressure
Several studies have shown that people with obstructive sleep apnea are at a much greater risk of having high blood pressure. OSA causes your oxygen level to drop. Your heart beats faster due to the lack of oxygen. This causes your blood pressure to rise. Over time, this can lead to an ongoing increase in blood pressure. It is important to treat high blood pressure since it is a proven cause of other forms of cardiovascular disease. This includes heart attack, heart failure and stroke.
But treating high blood pressure may not be enough. When high blood pressure does not respond well to treatment, it is often due to the presence of untreated sleep apnea. Once the OSA is treated, then the high blood pressure tends to improve as well. It is vital for your doctor to determine if a sleep disorder such as OSA is a factor in your high blood pressure.
What Does It Mean If Your Resting Heart Rate Is High
There are a number of reasons why your RHR may be high and usually, there are simple solutions to combat that. Metabolism is a key indicator in an increased heart rate, so try eating or exercising earlier in the evening. If your heart rate goes up right after you fall asleep, then chances are youre just overly tired. To have a consistent heart rate, try to keep your bed time routine consistent. This will also help you get a better nights sleep. By having a consistent night time routine, your body wont have any surprises and youll be able to take perfect care of your heart rate!
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Hrv Changes Due To Hypoxia
Exposure to hypoxia is a leading cause of oxidative stress, inflammation, and sympathetic hyperactivity . Recurrent oxygen desaturation induced by sleep apnea, one of the distinct features of OSA differing from non-OSA, may be associated with elevated sympathetic nervous activity and blood pressure . Additionally, Watson et al. found that the severity of hypoxia is related to graded autonomic dysfunction. Both animal and human experiments demonstrated that the failure to restore cardiovascular adjustment capacity can be ascribed to impaired nerves and blunt responses of the autonomic system as a result of intermittent hypoxemia in OSA . A systematic review shows that either SpO2 or SaO2 used to assess arterial oxygen saturation is correlated with time-frequency HRV during hypoxia in normal people at rest . Botek et al. found lower arterial oxygen saturation in significantly reduced vagal withdrawal and increased sympathetic-vagal balance, suggesting SpO2 level is related to the reaction of autonomic control to hypoxia. Their aim was to investigate if HRV could be used as a predictor of SpO2 response to hypoxic challenges in subjects normoxic at rest. Nevertheless, it is admitted that changes in detailed HRV parameters are not consistently similar due to the varying experimental protocols .
Daytime Sleepiness And Hrv
On the other end of arousal, daytime sleepiness, a multifactorial psychophysiological state, is one of the predominant symptoms in OSA . Currently, the existing findings suggest that daytime sleepiness depends on the quantity and quality of prior sleep. Patients with OSA commonly suffer from reduced sleep quality that is related to fragmented sleep . Sleep disturbances caused by arousal are important contributors to sleepiness . Moreover, the frequency of arousal has more impact on sleep recovery than the amount of sleep . Subjective and objective sleepiness is often assessed by the Epworth sleepiness scale and multiple sleep latency test . ESS is a measure of a person’s general daytime sleepiness, where a score 10 could be diagnosed as excessive daytime sleepiness. As a gold standard, the cut-off point of MSLT is still debatable based on the types of patients. According to the AASM, a sleep latency during MSLT of < 8 min is defined as sleepiness. However, it is also suggested that mean sleep latency in MSLT < 5 min is considered as pathological sleepiness, 510 min is suspected sleepiness, and 1020 min is normal .
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