Hans Van Dongen spends his waking hours thinking about sleep. Or, to be more accurate, lack of sleep.

An expert on sleep deprivation and how it affects the way we make it through the day, Van Dongen, a research associate professor of sleep and chronobiology in Penn’s School of Medicine, also knows more than most people about the biological clock. His current research involves studying the effects of both sleep loss and jet lag on astronauts.

But Van Dongen is quick to point out how little he knows about the non-scientific approach to sleep and dreams. That’s why he proposed the topic as the theme for this year’s Penn Humanities Forum.

“ I figured this was one everybody can talk about it and has an opinion about,” says Van Dongen.

Since accepting the role of topic director for this year’s Forum, Van Dongen has been busy finding speakers, which include a former astronaut, a New York architect, an expert on myths and fairytales and a fatigue management guru, as well as leading sleep scientists from Penn and elsewhere.

“ Some of the speakers I know, others I haven’t got a clue about, but I will learn from that, which is nice,” he says.

Q. You’ve devoted your career to studying sleep, but in general do you think it has been a neglected subject?
A. If you consider how important sleep is in people’s lives, and how much time we spend sleeping, it hasn’t been studied that much.

Q. Why not?
A. First of all, we got a late start. It wasn’t until the 1960s that people realized that sleep was not a blank state where nothing happens. In fact it was very active. And that started the whole thing. Another reason is that it’s a very difficult field. We still don’t know what sleep is for. We’ve got theories, but none of them have been proven.

Q. I’ve heard people say they do fine on six hours of sleep. Are they just wrong?
A. Your perception of your ability may not match at all your actual performance. It seems that for very short periods of time if you just have to do something very quick or focus very quickly, even with sleep deprivation you might still be able to perform that task well. For something that requires extended attention or if you have to continue to do a task over a long period of time, then the deficit shows. People in normal life don’t engage in long tasks on a regular basis so as far as they can tell things seem to be going fine and it’s only when they’re driving home after a long day, for example, that the deficits get exposed.

Q. If sleep is so important, why do you think most of us continue to give it short shrift?
A. What people do in their lives is trade out things. They prioritize what they think is most important. It’s so hard to recognize how important sleep is because oftentimes nothing goes wrong if you’re sleep deprived. The problem is that oftentimes is not always. And when you do get in an accident then the consequences are disproportionate.

Q. Why are some people “owls” and others “larks”? Is it just a personality thing?
A. One of the papers that came out of my Ph.D. dissertation showed that morningness and eveningness, as we call it, originates from a group of cells in the brain. It’s not a personality trait and although you might be able to overcome it, you can’t actually change it. As for the reason, we don’t have a definitive answer to that. There are some theories that have to do with evolutionary reasons that would make the difference useful. The idea would be that in animals, for instance, it would make sense for different animals not to come to the same resource like the drinking pool at the same time. They would scatter over the day by virtue of the biological clock. That’s one hypothesis, though to prove that would be virtually impossible.

Q. Are you an owl or a lark?
A .I’m definitely an evening-type person. That’s one of the reasons why I scheduled this interview this late in the morning.

Q. If six hours of sleep is too little, what happens if you sleep a lot more than that? Can you then stay awake longer and still perform well?
A. You can’t really bank sleep as far as we can tell. You can’t oversleep and then hope to spend it later in wakefulness. If you go over that 16-hour boundary of wakefulness each hour seems to cause wear and tear on the brain. The longer you stay awake the more you add to that wear and tear.

Q. The Forum is on dreams as well as sleep. Do you study dreams here?
A. Dreams have been interpreted a lot, but in a strictly scientific context dreams are very hard to study. One thing we do know is that, whereas we used to think dreams were tied to the REM sleep state, that seems no longer to be true. Now it seems they’re just easier to recall when we have them in REM sleep. One of the reasons the Humanities Forum is interesting to me is that I have virtually no idea how dreams have been studied in other fields.

Q.Tell me about your current research.
A. I’ve been working a lot with reconstructing life in space. The main issue is that we’ve shown that six hours of sleep on a regular basis is not sufficient, but in space for reasons that are not quite clear astronauts only sleep roughly six hours a night. It follows then that they would suffer the consequences of sleep loss, including performance impairments, and that might have big implications, because you can’t afford to make an error in space.

Q. So how do you mitigate that?
A. Since astronauts suffer jet lag and sleep loss, we’re trying to come up with schedules that assign their most challenging work at times when they’re most alert. We’re also trying to predict who will deal better with sleep deprivation. If you have a small crew, you might want to send the person who’s most resilient out to do the job. We’d like to get a sense of who’s going to be most vulnerable to sleep deprivation.

Q.Back to the Forum, what talks are you most looking forward to?
A. I put in a strong vote for Robert Stickgold [October 20]. He’s one of the people who argues that sleep plays a role in learning and memory. That will be a really fun presentation. I also brought in Mark Rosekind [November 3], who’s a fatigue management expert. He tells people how they can manage problems related to sleep loss.

Q. Other highlights?
A. The concert by Marc-Andre Hamelin and Jody Karin Applebaum [October 12] will be a real treat. I know them personally and they’re fabulous.

Q. I understand you’re a tenor vocalist yourself.
A. Yes. I used to have a band when I was in the Netherlands. I sing classical songs but I don’t perform at the moment. I don’t have time. Sleep deprivation is a 24-hour business here. We never stop.

For more information on the Penn Humanities Forum, go to http://humanities.sas.upenn.edu.