Science Interviews


Tue, 20th Jan 2015

Fighting off sleepiness

Dr Nancy Wesensten, Center for Military Psychiatry and Neuroscience

Listen Now    Download as mp3 from the show The Secrets of Sleep

Work, friendships, exercise, parenting, eating, reading — there just aren’t enough Soldiers Dismantling Patrol Base in Afghanistanhours in the day to get all these things done! So, many of us find our day-to-day activities eating into the time when we should be tucked up in bed. But what are the consequences of sleep deprivation? Nancy Wesensten is a research psychologist at the Center for Military Psychiatry and Neuroscience at the Walter Reed Army Institute of Research in Maryland and she told Chris Smith how she's finding ways to fight the effects of sleep deprivation in soldiers...

Nancy - So, we know that in deployed environments, the soldiers report that they're often getting less than 6 hours of sleep per night. So, we’re looking at a substantially reduced opportunity to sleep in soldiers in deployed settings.

Chris - What effect does that have on the people when you measure how they perform when they're subject to this sustained loss of sleep?

Nancy - Right. So, when we bring volunteers into the laboratory and we deprive them totally of sleep, which we’ve done for up to 3 nights in a row, the main characteristic that we see in their performance is their response time to any kind of stimuli is substantially slowed. So, what this translates to in the field environment is basically, your ability to respond rapidly is degraded.

Chris - Do we know why that happens?

Nancy - Yes. We have some ideas based on brain imaging where if we sleep deprive individuals, and then we look at the brain activity while they're awake and sleep deprived, what we see is that glucose utilisation or that is metabolic activity in the brain is reduced. And those areas of the brain that are more metabolically deactivated by sleep loss, that is the areas of the brain that appear to be particularly susceptible to sleep loss also turn out to be the areas of the brain that are involved in higher order cognitive processes such as decision making, anticipation, the ability to formulate novel responses. All those kinds of things that we know are important in the operational setting.

Chris - Do you think that those areas become less metabolically active as a protective mechanism, that the brain is effectively tired and therefore, it turns down their thermostat if you like and just ticks along a bit slower in order to limit damage?

Nancy - That's possible. We don't know the answer to that for certain. But that's definitely a hypothesis that's being investigated.

Chris - What about doing something about it? A strong cup of coffee being at the fairly modest end of the scale, there are also now drugs that increasingly, students, academics, we’ve got reports that maybe 1 in 5 academics are taking drugs like modafinil which apparently boost their cognition, but also keep people awake. They can do all nighters and things and so, they get no cognitive, no brain decrement from doing this. What about chemically helping these soldiers?

Nancy - We can in fact use drugs or other naturally occurring substances such as caffeine to temporarily boost mental performance to well-rested levels. Caffeine for example, a lot of us use caffeine on a daily basis but caffeine and compounds such as modafinil and dextroamphetamine, they are only temporary patches. Eventually, you do have to make up the sleep that's lost. Now, you don't have to make it up on an hour by hour basis. So for example, if you lose 2 nights of sleep, you do not have to then subsequently sleep an extra 16 hours in addition to your regular sleep to make that up. What happens is that your sleep deepens so that you actually payoff the sleep debt by deepening sleep, but you do have to some extent also increase the amount of sleep you obtain as well. So, there's no free lunch. If you take a substance to temporarily restore performance, you have to pay the price sooner or later.

Chris - Is there a price to pay in the long term? Could robbing Peter to pay Paul in this way lead to long term brain damage?

Nancy - There's no evidence right now that insufficient sleep causes brain damage. We believe based on laboratory results that in the short term, not obtaining sufficient sleep can cause glucose intolerance and things that eventually will lead to type 2 diabetes. But right now, again, the long term consequences of insufficient sleep are speculative. It’s correlational in nature.


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