There are certain occasions where it's considered pretty normal to hear your own heart beating - examples being during a medical examination, or the pulsating in your own head following rigorous exercise.
But if you're someone who hears this sound when your head hits the pillow at night, this could indicate that a health risk is brewing behind the scenes.
Someone who has recently shed light on this concern is Detroit-based physician Dr. Anthony Youn.
The medic often goes viral online after sharing examples of overlooked ailments and doling out wellbeing advice on TikTok, and this week, he turned his attention to the heart.
In his latest lecture, Dr Youn began by firstly disclosing that, in the majority of cases, hearing your heart beating - whether audibly or inside your own head/ears - is a pretty normal phenomenon.
The condition affects sufferers the most when they're lying on their sides (Koldunova_Anna/Getty) "If, every once in a while, you’re lying on your side and you hear your heart beating, it’s most likely your carotid artery basically sitting against your pillow," he began.
Apparently, however, if you catch wind of the unnerving beating on a relatively regular basis, this could actually be one of the earliest signs of a chronic hearing condition.
"If you’re hearing your heart beating all the time when you’re lying on your side, or especially when you’re standing up, then it could be pulsatile tinnitus," the board-certified plastic surgeon disclosed.
What is pulsatile tinnitus?
According to the NHS, this condition is a variation of tinnitus, which describes the perception of sound even when there is no source.
In its regular form, this ailment often leaves patients enduring an uncomfortable sound, like ringing in the ears or a buzzing sensation.
In cases of pulsatile tinnitus, however, the sound has been described by sufferers as somewhat rhythmic and is heard regularly in the head and ears as a heartbeat.
This is triggered by a change in blood flow in the vessels near the ear and has been described by others as a 'swooshing' sound, similar to their actual pulse.
One patient recently told the New York Post that the sound is somewhat like 'a washing machine in a spin cycle and a vacuum'.
It's most prominent in sideways sleeping (Daniel de la Hoz/Getty) What are the causes of pulsatile tinnitus?
According to the Cleveland Clinic, several conditions may be the cause of pulsatile tinnitus, including:
- Anaemia that increases blood flow and the amount of noise in your head
- Head injuries that affect veins and arteries near your ears
- Atherosclerosis that can cause uneven blood flow
- Hyperthyroidism, which may increase heart rate and boost blood flow
It can also be sparked by a blockage in the ear, as well as high blood pressure, narrowed veins or arteries in the head and neck, an obscured connection between arteries and veins, or benign head or neck tumours.
High blood pressure during pregnancy can also be a cause, HealthyHearing.com says, with 1 in 3 women experiencing tinnitus while expecting.
According to Tinnitus UK, the chances of doctors finding a specific cause for pulsatile tinnitus are more likely than for regular tinnitus, but it is still difficult.
NHS experts also advise that, if you suspect that you're beginning to experience pulsatile tinnitus, you should speak to your GP, who will suggest tests and treatments.
"Although it’s usually benign, there are some potentially concerning causes, so it’s best to see your doctor," Dr Youn said.