Multiple Sclerosis and Sleep Disorders: Fatigue and Daytime Sleepiness
Earlier this month, I learned that I have mild sleep apnea. The path that led to my diagnosis was a bit round-about. If you remember in April, I was dealing with some increased anxiety and depressive symptoms. We increased my antidepressant and I received an as-needed anti-anxiety medication. Both were very helpful.
When my rheumatologist learned of my increased symptoms, which also included extra fatigue and daytime sleepiness, she wanted to discuss the possibility of sleep apnea. My rheumatologist ordered an overnight sleep study. The most common sleep study is the polysomnogram (PSG) which uses sensors (applied to the scalp, face, chest, limbs, and a finger) to record brain activity, eye movements, leg movements, body position, respiratory rate, heart rate, blood pressure, and blood oxygen level while you sleep.
During my night hooked up to the PSG equipment, I experienced 13 instances of apnea and 22 instances of hypopnea. When airflow is reduced by at least 80 percent, an episode of apnea is noted. Hypopnea occurs when airflow is reduced by 50 to 80 percent, accompanied by a drop in blood oxygen level. A sleep study report will indicate the number of times each occurs in total and as an index.
Apnea Hypopnea Index (AHI) is the number of apneas and hypopneas per hour of sleep. Respiratory Disturbance Index (RDI) is the number of apneas, hypopneas, and respiratory effort-related arousals (RERAs) per hour of sleep. Sleep apnea is defined as an AHI of greater than five events per hour. An RDI of 5 to 15 indicates mild sleep apnea, 15 to 30 is moderate, and more than 30 is severe.
My overall AHI was 5.4 and RDI was 12.9. The number of respiratory disturbances increased during REM sleep, giving me a RDI during REM sleep of 26.7. More disturbances also occurred when I was sleeping on my back rather than on my side. During 6.5 hours of sleep, I woke up nine times and became aroused 198 times. My arousal/awakening index was 32.09 (per hour of sleep). Wow.
For more information regarding sleep apnea (a chronic condition characterized by disrupted breathing during sleep), its symptoms, diagnosis, and treatment, please read my posts - Sleep Apnea: Is RA Connected to Sleep Apnea? (Part One) and Sleep Apnea: How is it Diagnosed and Treated? (Part Two).
Multiple Sclerosis and Sleep Disorders
The most common type of sleep apnea is obstructive sleep apnea (OSA), in which the airway collapses or becomes blocked during sleep. Loud snoring, snorting and/or gasping for air may occur as a result. Central sleep apnea, which is less common, occurs if your brain fails to send the correct signals to your breathing muscles. You are not likely to snore with central sleep apnea as your body simply makes no effort to breathe for brief periods of time. Central sleep apnea and obstructive sleep apnea can occur independently or concurrently.
Results of a recently published study suggest that patients with MS have a predisposition for obstructive sleep apnea and accompanying central apneas, especially among MS patients with brainstem lesions. Three groups of patients were included in the study: 48 patients with MS, 84 age/gender/BMI-matched patients without MS referred for sleep study, and 48 randomly selected sleep laboratory-referred patients without MS (Braley, 2012).
MS patients had higher mean AHI (apnea hypopnea index; 17.02 vs. 9.16) and CAI (central apnea index; 3.47 vs. 0.35) as compared to control groups. Among MS patients for whom MRI data was available (n=41), those with brainstem involvement (n=24) had significantly higher AHI (21.28 vs. 8.67) and CAI (6.12 vs. 0.14) than the control groups. For MS patients without brainstem involvement (n=17), the difference in AHI vs. control group was less (11.24 vs. 7.60), and CAI (0.99 vs. 0.34) did not significantly differ.
In a previous study, the relationship between fatigue and sleep disorders was examined in 66 MS patients using PSG testing (Veauthier, 2011). The group was stratified into a fatigued MS subgroup (n=26) and a non-fatigued MS subgroup (n=40). Testing revealed that 96% of the fatigue group suffer from a relevant sleep disorder, along with 60% of the non-fatigue MS group. Of the entire cohort, eight patients (12.1%) suffered from sleep-related breathing disorders (7 in fatigue group, 1 in non-fatigue group). Sleep-related breathing disorders were more frequent in the fatigued MS patients (27%) than in the non-fatigued MS patients (2.5%).
The Veauthier study (2011) demonstrates a significant relationship between fatigue and sleep disorders. Patients with sleep apnea, whether OSA or CSA, complain about fatigue, lack of energy, or tiredness more often than sleepiness (Cherwin, 2000). Braley et al. (2012) suggest that neurologists should consider sleep apnea as a potential cause of fatigue in patients with MS, especially those who have brainstem lesions. When sleep apnea is treated, complaints of fatigue and sleepiness tend to improve.
Untreated sleep apnea can lead to depression, heart disease, diabetes, obesity, and excessive daytime sleepiness. Stress hormones released during frequent drops in blood oxygen level caused by sleep apnea increase the risk of high blood pressure, heart attack, stroke, irregular heart beats (arrhythmias) and heart failure. Excessive sleepiness can lead to fatal car crashes and accidents at work.
If you suffer from fatigue and/or your housemates notice that you stop breathing, snore or gasp for air while you sleep, please talk to your doctors about the possibility of sleep apnea or another sleep-related disorder. It's better to get tested and treated than to risk your cardiovascular health.
SOURCES and SUGGESTED READING:
Attarian HP, Brown KM, et al. The Relationship of Sleep Disturbances and Fatigue in Multiple Sclerosis. Arch Neurol 2004 Apr;61(4):525-8.
Braley TJ, Segal BM, Chervin RD. Sleep-disordered breathing in multiple sclerosis. Neurology 2012;79:929; Published online before print August 15, 2012; DOI 10.1212/WNL.0b013e318266fa9d
Chervin RD. Sleepiness, fatigue, tiredness, and lack of energy in obstructive sleep apnea. Chest 2000;118:372-379.
Manon-Espaillat R, Gothe B, Ruff RL, Newman C. Sleep Apnea in Multiple Sclerosis. Neurorehabil Neural Repair 1989;3:133. DOI: 10.1177/136140968900300304
Stanton BR, Barnes F, Silber E. Sleep and fatigue in multiple sclerosis. Mult Scler 2006 Aug;12(4):481-6.
Veauthier C, Radbruch H, et al. Fatigue in multiple sclerosis is closely related to sleep disorders: a polysomnographic cross-sectional study. Mult Scler 2011;17:613; originally published online 28 January 2011.
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