Insomnia among Service members receives a lot of well-deserved attention, as evidenced by the need for the Cognitive-Behavioral Therapy for Insomnia (CBT-I) workshops CDP provides. That said, insufficient sleep or sleep deprivation is arguably more common. Data shows while approximately 20% of soldiers score above the cutoff score on an insomnia screener (Taylor et al, 2016), 69-72% of Service members obtain six hours or less sleep nightly (Mysliwiec et al, 2013; Luxton et al, 2011). In other words, only a little over a quarter of Service members get into the recommended range of 7-8 hours of sleep nightly. Personally, I would go so far as to say that even seven hours of sleep is insufficient for the majority of people based on my evaluation of sleep research.
So, let’s take a deeper look at what exactly the research does say about insufficient sleep. In this blog, I will interview Dr. Tracy Jill Doty, a cognitive neuroscientist at the Sleep Research Center at the Walter Reed Army Institute of Research who has been studying among other topics sleep deprivation, alertness, and performance.
1. We all would probably like to get a little more sleep. So when we say that Service members experience insufficient sleep or sleep deprivation, how is that operationally defined in research?
TJD: Previously sleep in our Service members was almost exclusively defined by self-report. Unfortunately self-reported sleep can differ wildly from actual sleep. We have an operational research arm of our group (the Behavioral Biology Branch) that is going out into the field and measuring sleep objectively with actigraphs. We currently have over 2000 research grade actigraphs that are being taken out into various field environments. The team is currently analyzing those data and hope to publish some of the first large-scale studies of objective sleep in the military soon.
2. What are the consequences of sleep deprivation?
TJD: Major consequences include impaired executive functions – judgment, problem-solving, and decision-making capabilities take a hit - as well as slowed reaction times and reduced ability to concentrate. Other consequences are decreased mood and motivation, and increased irritability. I would also add that it suppresses your immune system, making it harder for you to fight off colds and heal from infections.
3. In the military, we emphasize the impact of substances, such as alcohol, on readiness and fitness for duty. There are many programs aimed to reduce alcohol use, such as “0-0-1-3” and “That Guy/Girl.” So how does sleep deprivation compare to say being intoxicated when it comes to duty performance?
TJD: Previously published literature shows a linear relationship between the cognitive deficits caused by sleep loss and those caused by alcohol; that is, the impact of sleep deprivation directly compares to the impact of being intoxicated. Our group developed the 2B-Alert webtool in collaboration with the Biotechnology High Performance Computing Software Applications Institute (BHSAI). Anyone can use the webtool for free by registering using the “Register” button on the page. You can enter your sleep schedule and caffeine consumption and the tool will predict your performance and also show if/when you reach the equivalent of 0.05 and 0.08 BAC. There will be a new version of the webtool coming soon which will allow you to receive recommendations of when and how much caffeine to take in order to optimize performance during a defined time period.
4. How do we measure sleep deprivation? Is there a biomarker?
TJD: How to measure the impact of sleep deprivation is a great question. We talk about this as a fatigue biomarker. We know from previous work from our group and other groups that sleep loss impacts individuals differently. So it is not enough just to know how much sleep loss someone has, but also to understand how that sleep loss is impacting their functioning. The 2B-Alert algorithm has an app component in development that will do just that. It allows the participant to take the Psychomotor Vigilance Test (PVT) on the smart phone. The PVT is the gold standard for measuring the impact of sleep loss on attention. It is a very simple reaction time test that is incredibly sensitive to sleep loss. It is probably our closest “biomarker” of fatigue, but it does require the person to sit down for 5 minutes to do the test, which is not great for the field, to ask someone to stop what they are doing and sit down to take a test on a phone. We are actively seeking biomarkers that can continuously be measured with no interference in the person’s daily life, but it is a tall order.
5. What are clues that someone is chronically sleep deprived on a regular basis?
TJD: It’s important to note that we are all very bad at being able to recognize how much sleep loss impacts us. So asking someone if they are sleep deprived is usually not accurate. This is another example where the PVT is critical to understanding how sleep loss impacts an individual. One of the most prevalent phenomena that occurs with sleep loss is lapsing. The PVT measures lapses along with basic reaction time. Lapsing is where you space out for a short period of time. This occurs more and more frequently with sleep loss.
6. We know that a person can feel subjectively alert and awake, and still have reductions in their performance. What are countermeasures for insufficient sleep that not only improve alertness but also resolve performance impairments?
TJD: There’s no magic pill, eventually countermeasures will fail. We have a recent study showing that caffeine stops working after three nights of chronic sleep restriction (i.e., 5 hours sleep/night). Eventually you just have to sleep.
7. It seems like the best solution to not getting enough sleep is to get more sleep, even though that might not be as simple as it sounds. Is that a fair summary?
TJD: Yes! Sleep seems like a simple answer, but it can be difficult to find time to sleep or difficult to have quality sleep. We have the mantra that more sleep is better. Of course, as you start to pay off your sleep debt, sleeping more gives you less of a return. There are studies out there showing that mortality increases with more sleep – you see them in the popular media a lot. What you don’t see is that a lot, if not all, of these studies do not account for medication use and mobility and are often not done with objective measures of sleep. More sleep is always better. Our group’s mission is to attack the epidemic of sleep loss in the military from both angles-quantity and quality.
In summary, I think it is pretty clear to me the benefits of obtaining sleep. In the past, I used to think people were “X hour” sleepers, that if we got a specific, individually variable, physiologically determined number we would be good to go. Now, I am going to recommend everyone (and in particular Service members) maximize their sleeping opportunities as much as possible, especially before or after periods of acute sleep deprivation. I would like to take a moment here to thank Dr. Doty for all of her time and expertise in sharing her knowledge about this topic, and I would also like to encourage all of you to stay tuned for the results of her group’s study on objective sleep amounts in the military, and other research. Thanks Dr. Doty!
The opinions in CDP Staff Perspective blogs are solely those of the author and do not necessarily reflect the opinion of the Uniformed Services University of the Health Science or the Department of Defense.
Diana Dolan, Ph.D., CBSM, is a clinical psychologist serviing as a Military Behavioral Health Psychologist with the Center for Deployment Psychology at the Uniformed Services University of the Health Sciences in Bethesda, Maryland.