[music playing]

Vic: I like to sleep about eight hours a night I'd say, ideally.

Male Volunteer: There you go, Ollie.

Ollie: Thank you very much. I actually get a lot of sleep. Every evening I try to get as much as possible, at least eight hours. If I can get a few more in then I will try.

Male Volunteer: Pick your sizes, any size. I'm usually out late on the weekend, but I usually will sleep and I will stay around the house and just nod off in the afternoons.

Narrator: And they're off with just 59 hours, 59 minutes, and 55 seconds to go. For the next three days, we'll continually monitor our volunteer's performance, as well as physical tests. We'll be giving our Guinea pigs a series of intentionally boring tasks that will measure their judgment and ability to concentrate. As Ollie responds to this flashing light, his brain's activity is measured.

The smooth lines on his EEG mean he's awake and alert. And a driving test will recall the volunteer's ability to stay on the road. 60 hours is a long time, but all stimulants like tea and coffee, even chocolate, are banned from The Human Zoo. As the first day turns to the first night, the volunteers settle down in front of the TV. To help make sure they don't drop off, there's a security guard and a team of student minders.

It's getting to about half of us are getting a bit tired now so we're trying to do things to keep ourselves going.

[shouts]

[crash]

Narrator: As day breaks, our human Guinea pigs are feeling the effects of a sleepless night.

DR. ADRIAN KENDRICK: Well, the body needs to recover from the day's work. And what happens is that during part of sleep you get into very deep sleep. And this is what we think is the recuperative phase of sleep to make the body feel good the next day. Right. Well, folks, you're halfway through. How's it feel?

Vic: This morning I felt really elated. And in my lungs, my chest, I felt this very nervous feeling, but I didn't feel nervous. But it was like I had the symptoms of feeling quite anxious.

Male Volunteer: Last night was really, really heavy, but I think we've learned lessons from last night.

Vic: You need to be moving and jumping around.

Ollie: Yeah, really jumping around a bit.

Male Volunteer: Yeah.

Vic: Sitting is not good. Definitely.

Male Volunteer: No.

Narrator: Exercise helps them stay awake and warm. Later, Vic writes her website diary.

Vic: It's particularly late on Saturday night. In fact, it's— oh, no it's not. It's only 5 to 11, which isn't late at all.

Camera Man: It just feels late.

Vic: It just feels terribly late.

Male Volunteer: And I know that this is going to seem like a really long night like last night did and I'm not really looking forward to that too much to tell you the truth.

Ollie: Hopefully, we'll see each other through for the next few hours to Sunday morning.

[music playing]

Male Volunteer: It's 25 past 4:00 in the morning. We've done some 43 and nearly 1/2 hours. I'm not good. I'm really not good.

Vic: I'm not good.

Narrator: Dawn breaks. They've now been awake for two days and two nights.

Ollie: Last night was absolute hell to be quite blunt about it. It was very, very difficult. The last four hours, I would say, especially were— we all got to this state where unless we actually stood up and walked around—

Male Volunteer: We were going to fall asleep, weren't we?

Narrator: Just six hours left. Staying awake is proving extremely difficult. In the last round of tests, the volunteers are nodding off. You can see it in their brain activity.

DR. CHRIS ALFORD: This is what we call a microsleep. He's not only not processing the information, if something was to pop up in front of him he wouldn't see it. He's not going to respond. And that's also reflected in the eye channels here. We've got slow, rolling eye movements lasting several seconds. And that typical pattern you see as somebody begins to nod off.

DR. ADRIAN KENDRICK: You seem to have been traveling a bit off road here.

Ollie: Yeah. I think whether I actually dozed off longer in this period because actually in that period I'd gone so far off the road that I didn't quite know which direction to turn back in in order to find the road again.

DR. ADRIAN KENDRICK: Right. OK.

Ollie: So hence, I crashed.

Narrator: For 60 hours, he's nearly up. And even the thought of sleeping in the zoo is enticing. Cruel as it sounds, before we let our volunteers escape we want to measure their recovery.

Volunteers: 10, 9, 8, 7, 6, 5, 4, 3, 2, 1.

[alarm ringing]

Ollie: Good morning. I think that was a good sleep, that was.

Narrator: After 12 hours' sleep, the volunteers are assessed for their recovery. All three are revitalized. And Ollie and Vic are virtually back to normal.

Woman: We've got some of their results here. And what we're doing is recording their reaction time and how well they managed to drive in a straight line. And these are the results for Ollie before he had any sleep deprivation. He's doing pretty well. 24 hours later, not so good. 48 hours later, look at this. He actually ended up crashing.

Narrator: Not that surprising.

Woman: No, but with just 12 hours' sleep he's straight on the road again.