Restless legs syndrome and parkinson disease

I was taught that Restless legs syndrome (RLS) is not related to Parkinson Disease (PD), even though they can be treated with similar medications. However, here is a study that shows a potential relationship between RLS and PD. Researchers studied almost 23,000 men with self-reported RLS and documented PD. The results showed that RLS symptoms were associated with higher risk of developing PD during the first 4 years of follow up. This relationship was only statistically significant in the men with severe RLS symptoms, occurring 15 or more times per month.

The researchers speculate that RLS may be an early feature of PD, and be a distinct entity from RLS that is not associated with PD.

Sleep fragmentation and cancer

Some studies have linked obstructive sleep apnea (OSA) to cancer. This study shows that sleep fragmentation in mice was associated with larger, more aggressive tumors than mice that did not have sleep fragmentation. Since I don't have access to the full article, it's unclear how the sleep fragmentation was produced. Also, OSA can cause sleep fragmentation but also low oxygen levels, and low oxygen could be linked to tumors. Either way, it's thought that OSA causes a systemic inflammatory response, and this may be what is linked to cancer.

Low testosterone and sleep apnea

Foxnews has two articles about low testosterone (here and here). The diagnosis is being made more frequently and many more men are receiving testosterone therapy. I'm not writing about this topic to weigh in on the supposed controversy, but just to point out that neither article mentions the fact that obstructive sleep apnea (OSA) can be related to low testosterone. Specifically, untreated OSA may reduce testosterone levels. Also, OSA causes fatigue and sleepiness, and thus could mimic the symptoms of low testosterone. Therefore, if you suspect you have low testosterone or are diagnosed with low testosterone by your doctor, consider getting evaluated for obstructive sleep apnea if you snore regularly or have witnessed pauses in your breathing.

L-Carnitine and narcolepsy

Narcolepsy is a sleep disorder that causes excess sleepiness. Recently, a study has shown that narcolepsy may be associated with low levels of a compound called carnitine, which is involved in fatty acid metabolism. This study looked at the effects of supplementing L-carnitine in 28 patients with narcolepsy. The study was a randomized, double-blinded, cross-over, and placebo-controlled design that lasted 16 weeks. The participants took 340 mg of L-carnitine in the morning and 170 mg of L-carnitine in the evening. The participants were allowed to take traditional medications for narcolepsy. The primary outcome measure was the patient's subjective assessment of their sleepiness, which was based on the total time the person reported they dozed off during the daytime as recorded in their sleep logs. Of note, there was no objective measurement of sleepiness, such a multiple sleep latency test.

Results showed a statistically significant reduction in subjective dozing time when participants took L-carnitine. Specifically, participants dozed for 49 +/- 34 minutes / day on L-carnitine versus 58 +/- minutes per day on placebo. This may be statistically significant, but I wonder how clinically significant it is. Researchers reported no side effects to the L-carnitine.

The researchers also noted that low carnitine levels may be seen in chronic fatigue syndrome, and that it's been reported that L-carnitine supplementation resulted in significant improvement in fatigue severity after two months of use.