Chronic sleep restriction affects behavioral and ERP correlates of psychomotor vigilance - AKA My First Poster

I suppose this entry is technically late. Tuesday represented my big debut into the fascinating world of sleep research with my first-ever poster session. Sure, I was able to assist in a presentation in January at an aging conference but this was the first work that I've ever presented solo. It was both terrifying and exhilarating. I probably spent the first 15 minutes alternating between terror that someone would ask a question and worry that no one would ask me about my research. But, unsurprisingly, the session went well with polite, friendly people asking a few questions and some even complementing me on my research. And now that I've run through my little spiel in an academic setting, I feel comfortable in sharing it here on the internet. Keep in mind, this isn't an exact replica of my academic-version of the presentation because I know how daunting such technical jargon can be.

The Constellation in Baltimore's Inner Harbpr

My lab was interested in how chronic sleep restriction (a lessening, but not total deprivation of sleep) affects sustained attention, both as a behavioral measure and through recordings of EEG*. Past research has shown that the PVT (psychomotor vigilance task) is an accurate measure of sustained attention. For an abbreviated, modified version of the task, click here. But essentially, participants were asked to watch the screen and hit the spacebar whenever they saw a stopwatch appear on the screen.

Our experimental design began with recruiting 24 undergraduate students with no neurological or psychological problems (including sleep disorders). We had them come into the lab where we recorded resting state EEG (which is sort of a baseline cortical activity) and recorded EEG while they performed the PVT. We then gave them actigraphs (wristwatches that record movement and thereby objective measures of sleep-wake cycles) and asked them to fill out a sleep log entry each day. There were approximately 6 weeks between each of the 3 EEG sessions so we got a span of the full semester.

Based on this data, we found that average daily sleep decreased between session 1 and sessions 2 & 3 (from around 7hrs to 6.5hrs) and this negatively predicted reaction times on the PVT. In other words, sleep went down and time it took to react went up.

My poster

On the EEG side, we found the amplitude of the P3 component significantly decreased from session 1 to sessions 2 & 3. P3 is a change in voltage which has been linked to decision-making in past research. We also found that alpha reactivity amplitude decreased between session 1 and sessions 2 & 3. This component is a little difficult to explain in layman's terms, but essentially a lowered amplitude in alpha reactivity has been linked to dementia, traumatic brain injury, and aging.

The changes in P3 amplitude and alpha reactivity each negatively predicted reaction times both across and within-subjects. What makes this incredible to me is that we saw such clear effects from only avery small change in average daily sleep. We plan to look from here at more specific measures of sleep such as circadian rhythms and sleep latency.

So, that's more or less what I got to present at the conference. It was pretty incredible to talk to so many experts in the field and I look forward to attending next year (hopefully!). For now, I've just settled into my room at Albert Einstein College of Medicine and have started to learn a little about what I'll be doing this summer. More to come on the New York experience next time!

*EEG or electroencephalography is a technique used to record electric potentials created by brain activity and recorded through the scalp. EEG is known for its high temporal (time-based) resolution, but low spatial (location-based) resolution. This makes it good for looking at timing in activation in the brain, but we cannot always locate the origin of the activation.

After a successful, if exhausting, first poster session.

Sleep Conference 2013- The Stuff of Dreams

I can't believe I'm here in Baltimore, MD at the annual Sleep Conference! This is my first real academic conference and already I'm exhausted and delighted. There are talks and posters over an entire spectrum of sleep-related fields (cognition, disease, metabolic rates, etc.)

While I've had a full day of presentations, I think my favorite topic of the day has been sleep, circadian rhythms, and metabolism. I suppose it could be because this is the issue most relevant to my current lifestyle. As an undergraduate student, twice a year the dreaded finals swing around and you find people living in the library and barely sleeping. These same students, afraid to waste precious procrastinating studying time, bring boxes of goldfish and coolers filled with red bull to sustain them. Personally, I try to avoid this behavior but I'm not always successful. And it's usually on nights when I'm scarfing down a whole box of cookies that I wonder, 'how the heck can I be so hungry when I've been sitting perfectly still for the last 8 hours?'

Well I'm not saying that the Sleep Conference is my personal answer to this question, but there has been quite a bit of recent research linking sleep deprivation with increased hunger, caloric consumption, and (in the end) weight gain. What I found most interesting was that one study (which I believe came out of this link) showed that sleep deprived participants did consume more calories, but statistically consumed less calories per waking hour than non-sleep restricted participants. This indicates to me that caloric intake isn't the whole story, and perhaps metabolic rates are shifted because of the lack of sleep so that the calories consumed are not efficiently put to use.

Mind you, this is just my take on a particular presentation and I suggest checking out original sources such as this to get the full story. Please feel free to chime in on the comments below as well!