Dr. Kelly Olson

Tag: Research Note

  • Sleep Apnea + Symptoms and Causes

    Sleeping is good for the mind, body, and soul. Sleep apnea is a severe sleeping disorder that continuously starts and stops. One of the signs that you may have sleep apnea is if you snore loudly, but you wake up feeling tired or foggy even after a whole night of sleep.

    There are three main types of sleep apnea:

    Obstructive sleep apnea, which is a common form that occurs when the throat muscles are relaxed.

    Central sleep apnea occurs when our brain does not send proper signals to the muscles that control our breathing.

    Complex sleep apnea syndrome, also known as treatment-emergent central sleep apnea, which occurs when someone has obstructive and central sleep apnea.

    If you or a loved one believes they have sleep apnea, please see your primary doctor. Treatments can help ease your symptoms and may help to prevent future heart problems or other complications.

    How to know when to see your doctor

    Loud snoring may indicate a potential problem, but not everyone who has sleep apnea snores. Talking with your doctor about signs or symptoms you may have will help you get a good night’s rest.

    Sleep Apnea Causes

    Obstructive sleep apnea

    This occurs when the muscles in the back of your throat relax. These muscles support the soft palate, the triangular piece of tissue hanging from the soft palate (uvula), the tonsils, the sidewalls of the throat, and the tongue. When the muscles relax, your airway narrows or closes as you breathe in. Meaning, you are not getting enough air, which lowers the oxygen level in your blood.

    Your brain then senses your inability to breathe and briefly awakes you from your sleep so that you can reopen your airway. This awakening is so brief that you may not remember it. You may snort, choke, or gasp. This pattern can repeat itself five to thirty times (or more) each hour or all night. Thus, impairing your ability to reach a night of deep, restful sleep.

    Central sleep apnea

    This less common form of sleep apnea occurs when your brain fails to send signals to your breathing muscles. Meaning that your body makes no effort to breathe for a short period. You may awaken with shortness of breath or have a difficult time getting to sleep or staying asleep.

    Risk Factors

    Sleep apnea can affect anyone, including children. Certain factors may increase your risk.

    Obstructive sleep apnea

    These factors listed below are increased risk factors for this form of sleep apnea.

    Medical conditions: congestive heart failure, high blood pressure, type 2 diabetes, Polycystic ovary syndrome, hormonal disorders, prior stroke, chronic lung diseases, and Parkinson’s disease are just some of the conditions that may increase the risk of obstructive sleep apnea.

    Smoking: smokers are three times more likely to get obstructive sleep apnea than people who have never smoked. Smoking can increase the amount of inflammation and fluid retention in the upper airway.

    Family history: having family members with sleep apnea may increase your risk.

    Nasal congestion: If you already have difficulty breathing through your nose – whether from an anatomical issue or allergies – you are more likely to develop obstructive sleep apnea.

    Use of alcohol, sedatives, or tranquilizer: these substances relax the muscles in your throat, which can worsen obstructive sleep apnea.

    Being older: Sleep apnea occurs significantly more often in older adults.

    Excess Weight: Obesity dramatically increases the risk of sleep apnea. Fat deposits around your upper airway can obstruct your breathing.

    Neck circumference: Those with thicker necks may have narrower airways.

    A narrowed airway: You may have inherited a narrow throat. Tonsils or adenoids can also enlarge and block the airway, particularly in children.

    Central sleep apnea

    Heart disorders: Having congestive heart failure increases the risk.

    Using narcotic pain medications: Opioid medications, especially long-acting ones such as methadone, increase the risk of central sleep apnea.

    Stroke: Having a stroke increases your risk of central sleep apnea or treatment-emergent central sleep apnea.

    Being older: Middle-aged and older individuals have a higher risk of central sleep apnea.

    Being male: Central sleep apnea is more common in men than women.

    Sleep Apnea Complications

    Sleep apnea is a severe medical condition; complications may include:

    Daytime fatigue: When you have repeated awakenings associated with sleep apnea makes normal, regenerating sleep seem impossible. Therefore during the day, you are likely to have severe daytime drowsiness, fatigue, and irritability.

    Having daytime fatigue may leave you with difficulty concentrating and finding yourself falling asleep during your day-to-day tasks. Individuals with sleep apnea have an increased risk of a motor vehicle and workplace accidents.

    With the lack of sleep may come quick-tempered, moody, or depression swings. Children and adolescents with sleep apnea may perform poorly in school or have behavioral problems.

    High blood pressure or heart problems: When your body has sudden drops in blood oxygen levels that occur during apnea, increase blood pressure and strain on the cardiovascular system. Having obstructive sleep apnea increases the risk of high blood pressure.

    Obstructive sleep apnea may also increase the risk of recurrent heart attacks, stroke, and abnormal heartbeats. If an individual has heart disease, multiple episodes of low blood oxygen can lead to sudden death from an irregular heartbeat.

    Type 2 Diabetes: Living with sleep apnea increases your risk of developing insulin resistance and type 2 diabetes.

    Metabolic Syndrome: This disorder includes high blood pressure, abnormal cholesterol levels, high blood sugar, and an increased waist circumference. This is all linked to a higher risk of heart disease.

    Complications with medications and surgery: Obstructive sleep apnea is a serious concern with certain medications and general anesthesia. Individuals with sleep apnea may be considered to have high chances of complications after surgery because of being prone to breathing problems – considering when lying on one’s back and being sedated.

    Liver Problems: Due to sleep apnea, those individuals are more likely to have abnormal results on liver function tests. Their livers are more likely to show signs of scarring (nonalcoholic fatty liver disease).

  • Clinical Application of Brain Circuitry

    Specific brainstem regions regulate the transitioning of the five sleep stages. For example, NREM occurs when the noradrenergic LC and serotonergic dorsal raphe (DR) suppress the cholinergic pedunculopontine tegmentum (PPT) and lateral dorsal tegmentum nuclei (LDT) neurons. In contrast, entry into REM sleep is associated with a decrease in noradrenergic LC and serotonergic DR activity that permits enhanced activity of the cholinergic PPT and LDT (Pace-Schott & Hobson, 2002). Perturbations in neurotransmitter signaling between these nuclei can interfere with REM/NREM oscillations, leading to impaired sleep.

    Neurocircuitry utilizes maps depicting interactions between specific neuronal centers in the brain and periphery in order to relate urinary neurotransmitter output to central nervous functions. Activity in specific brainstem nuclei is associated with the release of neurotransmitters in the periphery (Lechin et al., 2004; Vgontzas et al., 1998). Analysis of night-time urinary neurotransmitters can be helpful in determining perturbations in neurocircuitry, and in guiding and monitoring therapeutic interventions. For instance, overactivity of certain wake centers in the brain can trigger sympathetic nerves to release norepinephrine in the periphery, with elevated urinary norepinephrine levels correlated with an overactive sympathetic nervous system (Vgontzas et al., 1998). Therapeutic strategies that successfully target CNS nuclei to regulate sympathetic outflow will result in a decrease in urinary norepinephrine output.

    In another example, exercise-induced increases in epinephrine correlate with a delay in REM sleep onset (Netzer et al., 2001), and total REM sleep is significantly lower following exercise (Netzer et al., 2001). Correlating with this, exercise has been shown to stimulate an increase in urinary epinephrine (Netzer et al., 2001). Therefore, urinary catecholamines appear to be biomarkers of altered REM sleep.

  • The Neurobiology of Sleep

    With the development of accurate and sensitive assays for measuring urinary and salivary biomarkers, researchers have made great strides toward understanding the brain circuitry that controls sleep-wake states (Burgess & Fogg, 2008; Lechin et al., 2004; Westermann et al., 2002).

    During wakefulness, the brain is kept active and alert by the actions of acetylcholine, norepinephrine, serotonin, dopamine, and histamine (Pal & Mallick, 2007). A region in the brain called the suprachiasmatic nucleus (SCN) entrains the body’s response to light (Turek et al., 2001), and is referred to as the master internal circadian clock (Castillo et al., 2004). Light activating photoreceptors in the eye promotes glutamatergic projections to the SCN. The SCN triggers several pathways that activate wake centers in the brain, such as the locus coeruleus (LC) and the tuberomammillary nucleus (TMN). The LC primarily releases norepinephrine, a neurotransmitter that contributes to elevated energy, mood, and vigilance (Comings et al., 2000). The TMN releases histamine, a neurotransmitter that promotes wakefulness and arousal (Wada et al., 1991). Excess release of norepinephrine and histamine results in a state of wakefulness (Lewy, 2002).

    In the absence of light, activity in the SCN is inhibited, while brain regions that are responsible for sleep such as the ventral lateral preoptic (VLPO) area and pineal gland are activated. The VLPO sends inhibitory GABAergic projections to wake-promoting centers in the brain, and in doing so reinforces sleep onset (Pace-Schott & Hobson, 2002). An increase in pineal gland activity results in the release of melatonin, a hormone that further dampens the activity of the SCN (Redlin, 2001). Therefore, excess release of GABA and melatonin results in a sleep-state (Lewy, 2002).

    There are four stages of sleep defined by electroencephalogram (EEG) readings, include three stages characterized as non-rapid eye movement sleep (NREM), and another stage classified as rapid eye movement (REM) sleep (Dotto, 1996). REM sleep encompasses dreaming, increases in respiration, heart rate, and body temperature. During a typical night’s sleep, a person completes five cycles of these sleep stages. The REM periods become incrementally longer with each cycle, ranging from 10 minutes to about an hour (Figure 2) (Dotto, 1996).