#How to know when to call 911

What the late Bob Saget might have assumed was a bruised head could be the reason he never woke up last month.

The comedian passed away on Jan. 9 while staying at a Ritz-Carlton in Orlando, Florida. Investigators found no sign of foul play or drug use.

However an autopsy revealed something perhaps equally scary: brain bleed.

Though no one can be sure what happened in the hours before the 65-year-old’s untimely death, Florida medical examiners concluded that he’d hit his head, fracturing his skull. Then he lied down and fell asleep.

The report also stated that Saget had bleeding and contusions to his brain and that his death was “the result of blunt head trauma.”

The fatal mishap left fans shocked — and wondering if the same could happen to them.

Indeed, even a mild headache following a bump or fall could spell a potentially fatal hematoma in the brain, a condition that causes the gaps in and around your mind’s organ to fill with blood.

It’s easy to overlook the potentially deadly signs, said Dr. Neha Dangayach, director of Neuroemergencies Management and Transfers for Mount Sinai Health System.

“Often adults who have headaches, they may think [it] is a simple headache, or they start self diagnosing themselves,” he told The Post.

But this can be an especially dangerous scenario for those who are prone to headaches, whether they’ve been diagnosed with migraines, cluster headaches or believe it’s just a bad hangover.

“Even in those patients who have other kinds of headaches, if they develop a headache, that is not the same as the headaches they usually get, or the intensity is much more, or it’s not going away … those are red flag signs, you have to get that headache checked out.”

Brain hemorrhage can present in different ways. Those who suffer severe head trauma, say in a traffic accident, will often become symptomatic within a few hours, presenting with excruciating headache, paralysis or coma.

In others, even a “trivial trauma,” a bump that one might forget occurring, could lead to a chronic type of hematoma that builds slowly over time, with much more subtle symptoms, Dangayach said.

“For patients who have chronic subdural hematomas, they may not develop symptoms right away, but over the course of a few weeks,” Dr. Dangayach told The Post.

Though it can happen to anyone at any age, risk increasing factors include underlying conditions such as high blood pressure, those taking blood thinners, and “frequent falls,” added Dangayach.

“It may be a second fall for them, or a third, which tips the balance of the developed symptoms because of rebleeding,” she added.

Symptoms of brain bleed can be acute — nausea, vomiting, seizures. But it’s often more much subtle than that, with signs of muscle weakness, impaired vision or a “new” sort of headache that develops over time, and won’t seem to go away even with medication.

Dangayach implores anyone who suffers from headaches to talk to a doctor, whether or not it turns out to be life threatening: “There are very good treatments available” for any headache. And, in the case of traumatic brain injury, timely treatment is key to survival.

“Patients should not wait,” she said. “You know, often it’s very sad to hear that somebody was developing symptoms, and they decided to sleep it off and didn’t come to the hospital. All of these treatments are time sensitive.”