Nancy Guthrie’s disappearance is being investigated as a possible abduction from her Arizona home in the early-morning hours, with experts raising concerns about her potential confusion and disorientation upon waking up suddenly.

The disappearance of Nancy Guthrie continues to raise new questions as experts examine what may have happened in the early-morning hours, which is when authorities believe the 84-year-old was abducted from her Arizona home. Guthrie has been missing since Sunday, Feb. 1.

Speaking about the case on the March 7 episode of Nancy Grace’s Crime Stories podcast, sleep specialist Pat Bryne said one particular scenario left him immediately” concerned, pointing to how the human brain reacts when someone is abruptly awakened in the middle of the night—especially during the deeper stages of sleep.

Expert Says Nancy Guthrie Was at ‘Very High Risk’ of a Heart Attack

Bryne explained that if someone is suddenly woken around 2 a.m., they may experience what’s known as sleep inertia, a period when the brain struggles to transition from deep sleep to full awareness, potentially leaving a person confused and disoriented for several minutes.

“So what I started to think about was what’s going on in her brain? What sleep stage was she at? And how did that affect her emotions and her thought process once she woke up? So our human brains do not go from fully asleep to fully awake,” he told Grace on the podcast.

“There’s this process and it’s called sleep inertia. There’s this process of waking up. And that depends partly on how you’re woken up and what sleep stage you’re at. So, at 2 a.m., [Nancy Guthrie] was probably either in a very deep sleep or in what’s called REM sleep, which is rapid-eyed movement sleep, which is where we dream. And the interesting thing about that is if she was in a deep sleep, then she would be incredibly confused.”

Byrne explained that Guthrie likely wouldn’t know where she was for a period of time, if she’d been woken up so suddenly. Couple that confusion with the fact that Guthrie had a heart condition (she had a pacemaker), and Bryne says it puts her at a “very high risk of a heart attack.”

“That concerned me immediately,” he said, before diving a bit deeper into the possible scenario. “The research just shows that elderly people who, even without heart conditions, are at a high risk of heart attacks and being violently woken up from a deep sleep. So that’s what the scientific research shows. And so you add on the fact that she has a pacemaker, which means she has a heart condition, makes it worse.”

Did Nancy Guthrie Leave Her Home Alive?

Investigators have not disclosed whether or not they have evidence that Guthrie was alive when she exited her home in the middle of the night (whether she walked on her own or was carried is also unclear).

There were drops of blood on the front stoop that were confirmed to be Guthrie’s, but it’s unclear where the blood came from exactly. In an interview with Fox News Digital, forensic pathologist Dr. Michael Baden explained that he believes that Guthrie was bleeding from the hands or face.

“The nature of the blood spots with little pale centers or donut shapes are typical for drops that come from the nose or mouth, because they’re mixed with air,” he told the outlet last month.