Human growth hormone and sleep quality

Human growth hormone (HGH) is popular amongst some athletes who use it for performance enhancement. A significant amount of HGH is secreted at night when asleep. Sleep deprivation can reduce HGH levels. HGH levels also naturally decrease with age. HGH can be used to treat certain medical conditions, like Prader-Willi Syndrome, which can cause sleep problems. I've not seen it used however in otherwise healthy people to improve sleep quality.

This study did just that - subjects took HGH at bedtime and reported significant improvement in time to fall asleep. They also had less time awake in the middle of the night and woke more rested in the morning. No reason for why HGH may improve sleep quality is given. Perhaps scientists will discover a novel mechanism of action to help those with reduced sleep quality.

Sleeping pills and heart failure

Patients with heart failure are at increased risk of having sleep difficulties. Sleep-related breathing difficulties like sleep apnea are also more common in heart failure patients. Here is a study that looked at sleeping pills and heart failure patients. Specifically, the researchers investigated the relationships between drugs prescribed at hospital discharge, going back into the hospital, and cardiovascular events in heart failure patients.

The results showed that sleeping pills increase the risk of cardiovascular events in heart failure patients by 8-fold. The type of sleeping pills that were most risky were the benzodiazepines like valium. At the end of the article, the researchers speculate that benzodiazepine sleep aids could reduce cardiac function or cause respiratory depression, and this could worsen any underlying sleep-related breathing disorders. The latter is certainly possible and underscores the importance of heart failure patients getting evaluated for sleep apnea. Prior to prescribing sleep aids, it's best to rule out sleep-related breathing disorders. If sleep apnea is present, that needs to be treated, rather than just giving sleep aids.

Sleep apnea and cardiovascular effects

Obstructive sleep apnea (OSA) is associated with high blood pressure and cardiac arrhythmias. When someone has a sleep apnea event, their heart rate typically slows down. Heart rate then speeds up during the subsequent recovery breaths. It's this repetitive slow-fast cycle during the night that is thought to contribute to arrhythmia. And research has shown that the more oxygen levels decrease during sleep apnea, the greater the risk to the heart and blood vessels. This study was done in a rat model of OSA. The results showed that the low oxygen levels from OSA damaged vital neurons in the rats' brains that regulate blood pressure and heart rate. This could explain why OSA increases risk of high blood pressure and cardiac rhythm problems. More research will be needed to determine if treating OSA can reverse the damage to those neurons.

Yawning may cool the brain

I sometimes get asked why we yawn and I am not sure. I was taught that it was to increase oxygen supply to the blood, but research has not demonstrated that definitively. This study showed that yawning may be a way that the brain gets cooled. Specifically researchers studied contagious yawning - that type of yawning which occurs when you see another person yawn. This is in contrast to spontaneous yawning. The results showed that contagious yawning was more common at warm temperatures. However, it was not more common at very hot temperatures, such as in Arizona in the summer.