An Interesting Link Between Sleep Apnea and Memory

Joshua March 28, 2017 4 Comments

If you’ve checked out our previous post on obstructive sleep apnea, you probably think you have a pretty good idea by now regarding the seriousness of the condition. But wait…there’s more! (Read that with epic foreshadowing, not unmitigated glee). Over years of study, scientists have derived a link between sleep apnea and memory loss, one which indicates that a lack of treatment of the former can actually accelerate cognitive deficiencies–especially in the elderly. While the link between sleep apnea and memory isn’t clearcut, there’s no doubt that just losing a single night of sleep can lead to an increase in what we call ‘senior moments’. Have you ever crammed all night before an exam and just totally drawn a blank while staring at the test paper? How about staying up all night before that big football game? Make no mistake, sleep interruptions don’t just have a short-term effect–they can cumulatively worsen your ability to retain and process information far into the future. This article intends to explore this phenomenon, with the aim of empowering you to better understand the impact of untreated sleep apnea on your memory.

Why Should This Matter to Me?

If you haven’t checked this out before, here are some interesting stats you should know:

• Approximately 40 million Americans suffer from sleep disordered breathing
• Of the 40 million mentioned above, 45% (~18 million) are likely to have sleep apnea
• 1 in every 15 Americans has moderate to severe sleep apnea, but 1 in 50 will go undiagnosed
• Drowsy driving is responsible for up to 100,000 car accidents, 40,000 injuires and 1,550 deaths annually
• Untreated sleep apnea can also affect bed partners, causing them to lose up to one (1) hour of sleep per night. In some cases where sleep apnea is accompanied by loud snoring episodes, bed mates have also been known to suffer mild hearing loss!
• 50% of hypertension patients also suffer from sleep apnea
• Sufferers of sleep apnea experience a risk of stroke that is four (4) times higher than normal
• Cardiovascular problems related to sleep apnea account for 38,000 deaths annually

Stats are great,?but funny thing is, not many people care about them. So let me bring this to you on another level. Has your partner, family, coworker (insert just about anybody here) ever complained about your snoring? Does your partner sometimes sleep in a separate room to get away from your nightly noises? Do people regularly compare you to a buzzsaw? Do you wake up at night out of breath, and/or do you?have regular nocturnal bathroom episodes? Do you find that you’re always tired in the day, even after getting the eight hours of sleep that are recommended? Is your on-the-job performance suffering because you’re always sleepy in the day? If your answer to any of these is a big YES, then go see a sleep specialist right away! It’s a small intervention that can have big payoffs for your future health and well-being. Remember you’re not just doing this for yourself…you’re doing this for your friends and family who want to have you around for as long as possible!

So…What Happens to My Memories?During Sleep?

As it turns out, your brain is awfully busy during sleep. Much of this activity is focused on replaying the day’s events, sorting through new data and stabilising existing memories to enable recall later on. If you’ve read our article on sleep architecture, you will realise that a lot of this takes place during stage NREM2 (Non-Rapid Eye Movement Stage 2), with proportionally less happening in REM sleep. This stage is so important that it takes up almost 50% of your sleep cycle. Thus if you were to shave your sleep time in half, for a single night, you would technically be making your ability to store and process new information 50% less efficient for the next day!

Acquisition of new information and recall of existing data happen all the time during our regular day-to-day lives. And as we age, we can definitely expect that some things will become harder to remember and that our ability to learn new concepts may also be affected to some degree.?That said, lack of sleep actually inhibits our ability to learn efficiently, and also impairs focus and concentration. Memory is really just a generic term for us, but our brain sees things differently. Some memories have to do with specific episodes in our lives (like your first graduation), while others simply deal with factual data (eg. the name of the presidents). We also heavily rely on procedural memory to do more complex tasks (like manage a project, etc) and these allow us to be meaningful contributors to our places of work, our families and society at large. Each type of memory is important, so it’s always best to make sure that we get enough sleep to keep our brains healthy.

How Exactly Does Sleep Apnea Impair Memory?

Hold on to your hats…this is where the fun (or not so fun) science comes in. Your brain has a little area within it called the hippocampus. It’s name is derived from the Greek word for ‘seahorse’ due to its characteristic shape. This part of your brain is responsible for–you guessed it–memory! To be very specific, it handles short-term and long-term memory along with spatial navigation. In this way, access to all the stuff you’ve ever learnt is controlled by this single area, which has complex relationships to other parts of your brain such as the neocortex. It goes without saying then that damage to this area can really mess with cognitive capabilities, such as our ability to remember names, and places. Indeed, the hippocampus is normally found to be the first brain locality that suffers damage in patients with Alzheimer’s disease. Patients with amnesia are also found to have physiological issues with said area in the brain.

Now that we’ve learnt about what controls how we process memory, let’s look at the chain of events that happen with untreated sleep apnea that can negatively affect our retention and recall. One of the major problems that tends to occur during an apneic episode is oxygen desaturation. That’s just a really fancy term for a drop in the level of oxygen in the blood. Normally this should range?anywhere between 94-98%, but suffers of obstructive sleep apnea can sometimes find themselves at dangerously low levels (oftentimes below 80%). This leads to a condition known as hypoxia, a condition characterised by inadequate oxygen reaching bodily tissues. This is known to affect the normal functioning of internal organs, and can even worsen existing health conditions. Since your brain is one of the busiest organs in the body, it is particularly sensitive to changes in oxygen levels (without oxygen, you can’t generate energy to fuel cells efficiently). In fact, cells without oxygen will undergo atrophy: a progressive degeneration which ultimately leads to cell death.

Tissues undergoing atrophy will normally show a notable decrease in size. Think of what happens to someone who may have broken a limb. When the cast comes off, the limb is very thin, because not only have they lost muscle mass, but the bone itself has become thinner from lack of use. If we relate this to the brain, which is doing memory processing and consolidation during sleep and needs you to breathe properly to supply it with oxygen, the end result is obvious. In severe cases of sleep apnea, hypoxia is equally severe. Low oxygen levels place the brain?under stress, and chronic stress has been shown to inhibit new cell growth. The cells in the hippocampus therefore fall into decline, which explains why suffers with sleep apnea usually display smaller hippocampal sizes?than those without the condition. Chronic hypoxia also causes a build up of ‘brain waste’, known scientifically as beta amyloid plaque. Your brain flushes this out into the lymphatic system during sleep, but if your sleep quality is poor and your sleep duration too short on a regular basis, you may end up with deposits in the brain tissue. While we’re not entirely sure that this causes cognitive deficiencies, we are sure it is associated with it.

Research has indicated that both snorers and sleep apnea suffers are?likely to exhibit cognitive impairment a full ten (10) years or more earlier than their peers who did not have those issues. This stacks up at the approximate ages of 77 and 90 respectively, a huge difference! Ultimately, apneic events can really shorten the overall time for which you are in full control of your mental faculties.

These facts also beg a scarier, more philosophical question.?Do your memories make you…well…YOU? In other words, if you took any random guy of the street and subtracted his memories, would he still be him (or her)? It’s said that persons with brain damage sometimes come back ‘different’. In a sense, that’s exactly what happens to people with Alzheimer’s, amnesia or traumatic brain injury. They’re never really the same again. Perhaps the mind-brain link is a bit stronger than we think.

Wow, That’s Scary! What Are the Treatment Options?

Thankfully, there are quite a number of options available, so it’s best to talk to your sleep specialist to determine which ones may be right for you.

• Continuous Positive Airway Pressure (CPAP): This tends to be the go-to solution for most sleep specialists. The technology used generates a steady stream of air though and a hose and mask intended to prevent the tongue and soft palate from obstructing the airway. Many CPAP machines leverage special sensory capabilities that help to detect when an increase in air pressure is needed. The best thing about CPAP treatment as well is that in some cases it has allowed partial repair of the hippocampus, hence improving memory! While proven to be an effective intervention however, not all patients remain compliant with the treatment. It should be used every night, but for various reasons some persons do not respond well. For some, they may feel mildly claustrophobic with a mask (indeed some have compared the full face mask to the facehugger from the move Aliens!). in others the pressure settings may actually disrupt sleep more than promote it. And yet others may suddenly start showing periodic limb movement disorder or restless legs syndrome for no reason at all. Sadly, this keep success rates at under 50%.

• Dental Appliances: For those who have difficulty complying with CPAP, oral appliance therapy is a great alternative. These come in two flavours: mandibular advancement devices (MAD) like the ZQuiet, or tongue retaining devices (TRD) like the Good Morning Snore Solution. The former works by repositioning the lower jaw so as to prevent the tongue from blocking the airway. The latter holds the tongue in the forward position without bringing the jaw forward. They both serve to accomplish the same thing: keep the airway open so as to reduce turbulence and obstruction, thus reducing the likelihood of frequent snoring and arousal.

• Orofacial Myofunctional Therapy: This is an increasingly popular form of treatment that works on the principle of proper head and neck posture. It emphasises breathing techniques along with postural alignment with the goal of ‘reshaping’ the oral cavity. Combined with sleep apnea exercises, this can actually have a very positive effect on those suffering from sleep disordered breathing.

• Surgery: There are a host of surgical solutions available. Most are focused on reshaping the soft palate so as to increase the size of the upper airway.

• Lifestyle changes: Many lifestyle factors can affect our breathing during sleep as well as our cognitive capacity on a daily basis. Obesity for instance can interfere with sleep since an increased neck circumference (due to fatty deposits) may contribute to laboured breathing. Bad allergies are another, but we can take several steps to manage these such as doing saline flushes, and using nasal sprays. Alcoholism has a sedating effect which can precipitate snoring and smoking can cause inflammation of the respiratory tract. Both are bad so please stay far away! Additionally, your sleeping position is also important. Some say sleep on your side, but our recommendation is to be on your back once you can avoid snoring problems. Keeping your brain healthy with physical exercise and learning challenges will also help to keep your memory skills sharp.

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In this article we covered the relationship between sleep apnea and memory. As you can observe, sleep disordered breathing can seriously influence your daily performance, and may even put you at risk for more serious conditions later on such as Alzheimer’s disease. It is my hope therefore that you will take this information seriously and start going about making changes that will improve how you breathe during sleep.

Have you ever noticed what happens to your memory when you’ve been sleep deprived for a while? Have you ever tried any of the recommendations above and did they work for you? Tell me your story in the comments below, I’d love to hear it!

Sleep well until next time.

–Josh