First presidential debate: Reading their body language

HOUSTON (KTRK) -- The first presidential debate will kick off in less than 24 hours, and each candidate will have a lot to talk about. But if you look closely, they'll be saying a lot more with nonverbal communication.

Presidential nominees Donald Trump and Hillary Clinton will be squaring off Monday night in their first presidential debate. While there's a lot to say, forensic body language expert Jan Hargrave says we should also be paying attention to what they're not saying.

"Everything we do with our body shows some kind of secret," Hargrave says.

From being sincere to insecure, Hargrave says there's a few things to look for, starting with Hillary Clinton.

RELATED: Hillary Clinton, Donald Trump look for victory at debate with expected record TV audience

"She's very difficult to read," Hargrave said. "She gives slight gestures of discomfort, or gestures of when she's really nervous or someone is picking on her. She does take her left hand and her left index finger and she does move them back and forth."

Another move to watch out for is head nodding.

"When you agree, you usually go two head nods. When you are ready for someone else to shut up, you typically go three or more head nods. So when you see her doing this a little bit too much, she wants to take the upper hand," Hargrave adds.

At the other podium, Hargrave says Trump's movement are quite abrupt.

"When Donald points, he points with his thumb up this way. Reminiscent of some kind of weapon that you're sending to someone. Anytime you point, that is teacher/student. It's as though someone is saying, 'I know better than you and you need to listen to what I'm saying,'" according to Hargrave.

"In body language, anytime you see a steeple formation is when you see the finger tips put together. in this kind of fashion. it's a big big sign of confidence."

If one of the candidates are not being truthful, watch out for these signs.

"When someone is not telling you the truth, there's certain displacements they do, primarily with the left hand and they do come and touch something on the left side of the face," Hargrave explains.

And no matter what they're saying in tomorrow night's debate, all eyes will now be watching to see what they're truly telling us.