Sleep & It's Effects on Memory - An Interview with Kelly Bennion, PhD. - Part 1
I had the opportunity to interview Kelly Bennion a researcher and faculty member in the Psychology & Childe Development department at Cal Poly San Luis Obispo on the topic of Sleep. Read more of our fascinating conversation below:
Jill: Would you please start by introducing yourself, where you earned your degree and how you came to be in San Luis Obispo.
Kelly: I am an Assistant Professor of psychology in the Department of Psychology and Child Development at Cal Poly. There I do a lot of research on how sleep affects cognition. I'm relatively new to the San Luis area; I started in the Fall of 2016, but prior to this I earned my PhD and Master's in Cognitive Neuroscience at Boston College, and then before that earned a Master's in Education from Harvard, focusing on how research from psychology and neuroscience can be applied to improve education. This was immediately following my undergraduate degree at Middlebury College in Vermont.
Jill: What made you choose the path of psychology and specifically memory and sleep which you are studying now?
Kelly: I think I came to psychology a very different way than many of my colleagues. I feel like you primarily become a professor either because you really want to teach, or because there is a specific experimental question that you are really interested in. For me I had always wanted to become a teacher. For instance, when I was five I wanted to be a kindergarten teacher, and when I was in middle school I wanted to be a middle school teacher, and then finally I got to college and became really excited about this idea of teaching not only to convey already existing knowledge, but also the ability to contribute to whatever field I was interested in. I took an Intro to Psychology class my first year of college that really piqued my interest and shortly following that I took a cognitive psychology class, which is where I became really interested in both sleep and memory. I had always loved school and learning about studying and test-taking strategies, but this also happened to be a time that I wasn't sleeping much (like many college students), so I became interested in sleep. Those two experiences helped me decide that this was an area I would be passionate enough about to contribute the field, and it seemed like a perfect blend of my interests.
Jill: Can you tell us about the sleep study that you are focused on?
Kelly: Most of my studies have to do with how sleep effects memory. What we know about the affects of sleep on memory is that they are not universal; rather, sleep selectively enhances memory for certain experiences over others. My interest in this started in graduate school, when my advisor, who mainly specializes in emotional memory, and her collaborator collaborator discovered that sleep selectively enhances memory for emotional experiences over neutral experiences. So for example, if you are held up at gun point, and then you go to sleep shortly after that, your memory for the details of the gun would be enhanced because that is the emotionally salient aspect of the experience. However memory for the neutral background details, like maybe the car the attacker drove up in, would actually be impaired. Essentially, there is an emotional memory "trade-off", and they found that sleep enhanced this trade-off; sleep selectively enhanced memory for the emotional aspect of the scenes, while impairing memory for the neutral parts. So I then became really interested in that finding - and more specifically the question of how sleep determines which aspects of your experience are important to remember. For instance, how does sleep know that it should preserve the details of the gun or what a poison ivy plant looks like relative to other plants? So I started investigating other questions that could help determine how information preferentially strengthened by sleep is essentially selected: For example, does the stress hormone, cortisol, predict our memory performance and does that interact with sleep to enhance memory? I've also started investigating heart rate variability and skin conductance response during those experiences to see how physiological arousal during an experience related to memory performance, depending on if you sleep or stay awake during the interval between experiencing something and then having your memory tested.
Jill: The interesting thing is that the two things you mentioned were kind of fear-based, and cortisol-based. You mentioned emotional responses, so what about the positive emotions?
Kelly: I was about to touch on that regarding my second line of research which although does not focus on positive emotions, it does have more positive implications for education. The first line of research we spoke about has implications for affective disorders, and perhaps even the development of PTSD. After years of focusing on the negative emotions, I then became curious about this question: If we know that sleep automatically strengthens memory for certain experiences more than others, is it possible that we can use sleep as a tool to enhance memory for the things that we want to remember? Essentially, what other tools (in addition to sleep) can we use to improve memory? What can teachers be doing to emphasize important information? Or if you highlight or bold information, or tell students that certain information is important for a later memory test, and then one group takes a nap and another groups stays awake - will sleep strengthen memory for those important, future relevant experiences? Some of my prior work shows that it does. There are certain ways that we can manipulate instructions to bias sleep to preferentially strengthen what we want to remember.
Jill: What do scientists know about sleep and what happens when we don't sleep?
Kelly: Sleep is immensely important. I am really excited that people in recent decades have become increasingly excited about sleep research, and that the public is taking sleep much more seriously. Let me step back a moment and say not all sleep stages are equal.
Each night we cycle through approximately 90 minute cycles comprised of Stages 1 and 2 (light sleep), and Stage 3 (deep sleep) - and then REM or Rapid Eye Movement sleep.
Deep sleep is particularly important for immune function, such as when recovering from a cold or flu. REM sleep, on the other hand, is really important for emotional processing. However please note that this is certainly an oversimplification of the science, but generally what studies have shown to be true. For instance come of the areas of the brain responsible for processing emotions are more active in REM sleep than when we are awake. Other areas, like the prefrontal cortex, which is important for logic and our critical thinking skills are deactivated during that stage. Our prefrontal cortex helps inhibit some of our emotional processing regions, such as the amygdala, which helps us be even keeled. However when we are sleep deprived, our ability for our prefrontal cortex to control our amygdala is weakened. Because our REM sleep is concentrated in later stages of the night, this is one reason why when we cut off our sleep in the morning, ability to keep an even keel.
Jill: So we may find ourselves short tempered?
Kelly: Exactly. Our prefrontal cortex down-regulating our amygdala helps us function on a daily basis without being overwhelmed with anxiety, stress or fear. But when you are sleep deprived, essentially that communication between the prefrontal cortex and the amygdala is severed and you instead tend to have an over-active amygdala. So, sure, you may be able to go through your day feeling more-or-less fine, but it is much more likely that something that wouldn't normally bother you when you are fully rested will be the thing that sets you off.
Jill: So if someone is cutting off this portion of their sleep on a regular basis, is it possible that it gets worse and worse? Is there an exponential effect?
Kelly: It does get worse and worse. What I often tell students is that you can't just make up your sleep. A lot of people wonder if they sleep 6 hours throughout the week but then get 9 or 10 hours of sleep on the weekends, does it average out? And the answer is that it doesn't. It takes a really long time to recover from from sleep loss. There are studies showing that even one hour of sleep lost from jet lag can take up to a week to recover. So, if you are crossing multiple time zones, it could take a full week to recover from that. Definitely get that extra sleep on the weekend if you can, as it will only do you good. However it is very important for you to get sleep on a regular basis.
Jill: Do you have any recommendations for better sleep?
Kelly: I think the biggest thing to focus on is how your sleep environment is set up. Most importantly, you need to create a quiet non stressful environment. So, if you have roommates, you might need earplugs to do that. Also your bedroom should be dark, so do your best to remove all artificial light in the room. I sleep with a sleep mask because there is a lot of ambient light from outside, or alternatively, blackout shades are really good for that function.
On that nite, light is really important to consider. Even an alarm clock with the typical red or blue digital display can be hidden inside a drawer or placed so that the display is not facing you. Similarly, you should place your cell phone face down and on silent, and make sure that the path from your bed to the restroom is clear so that you don't need to turn on any additional lights. Light is a really powerful signal for our body to reset its circadian rhythm. Ideally, sunlight is what resets this rhythm, and essentially tells us that it is time to wake up. Before artificial light, we operated on that system. In the evening hours, your body begins to produce the hormone melatonin which make you start to feel tired. Artificial light created by our phones, computer screens, and televisions is particularly problematic because the blue light emitted by these screens suppresses our own body's production of melatonin. So if you are having trouble sleeping, it is a good idea to turn off these devices at least an hour before bedtime. You can also try taking a melatonin supplement 30 minutes before bed time, but I'd first consider that you can reap a lot of the same benefits, just by getting off your phone and letting your body produce melatonin naturally.
Technically the bedroom should be reserved for sleep. So, even watching television or reading in bed can keep your mind too engaged. If you like to read in bed, perhaps you can instead read in a comfortable recliner chair or if you watch TV, perhaps you can do that on the couch, and then once you are tired, retreat to the bedroom. Even reading the paper, magazines, or books in bed should be done outside of the bedroom.
Jill: I had never thought about not reading in bed. I have heard about getting rid of the screens before bed, but I hadn't thought about reading being engaging in that way.
Kelly: Our bodies learn a lot of things through conditioning. So the more you can do to make your environment as simple and relaxing as possible, you should. If you don't have sleep problems, then you can continue to do what is currently working for you - but these are suggestions research has shown to improve sleep efficiency. Another thing that is important for those struggling with sleep is to try to not to stress about it. Particularly if you suffer from insomnia, it would be much better to get out of bed and do something calming, like have some decaf tea or read a book, and then return to bed when you are more tired. What can be really detrimental is if you are tossing an turning and you begin counting down the hours of sleep you are losing. So the more you can do to make sure that you don't associate your bedroom with a stressful environment, the better. For instance, even making sure that your desk is not in your bedroom is important.
Jill: It's funny you mention conditioning, I recently conditioned myself to put my phone to bed. Ariana Huffington started a company called Thrive Global, which is a wellness-based business, and she challenged us to put our phones to bed at night. So I bought the Phone Bed which is a charging station shaped like a bed with a little blanket and now I put my phone to bed at night before I get ready for bed. It really does help me get some down time. It's helped me let myself off the hook for having to read that email that comes in at 10:30 at night.
Kelly: Fun. Yeah, there is a lot you can do to create a routine. I think may people thinkthe idea of not being on your phone an hour before be is ridiculous - that they have to check their phone immediately before bed - but it is possible that with just some minor changes, you could change your routine: You could check your phone, put it in whatever special place you have for it, and then you brush your teeth and take a shower. There are also some apps that you can use, like the Flux App, which reduces the blue light emitted by cell phone screens and computers, so you don't have to worry as much about that issue.
If you'd like to donate to Kelly's further research at Cal Poly, you can donate here. Make sure to specify that you would like the donation to go toward "Bennion Sleep Research".
Part 2 of my Conversation with Kelly will appear in two weeks. Stay tuned!
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