A mysterious sleep disorder is now being uncovered by fitness trackers.
The disorder, known as sleep eating (eating in your sleep), is something many people don't even know they have.
Doctors suggest it often occurs when people try to stop smoking - and it can be discovered on devices like Fitbit, which tracks sleep and movement.
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According to sleepeducation.org, sleep related eating disorder (SRED) is a parasomnia. A parasomnia involves undesired events that come along with sleep. SRED consists of repeated episodes of compulsive binge eating and drinking after waking up in the night.
It adds: "Foods that are high in calories tend to be eaten the most. It is common to eat or drink thick and sugary foods such as peanut butter or syrup. The foods eaten during sleep are usually not preferred during the day."
One man, Jason Carny, has told how he was tracking his calories in the day but just wasn't losing weight.
He would wake up and find food wrappers in the kitchen. His Fitbit showed he had been up in the night as many as six or seven times.
Other health problems with the disorder can include: eating or drinking toxic substances, such as cleaning solutions; eating foods to which you are allergic; suffering from insomnia due to sleep disruption; sleep-related injury; loss of appetite in the morning; stomach pain; high cholesterol; excessive weight gain and obesity.
Dr Ranji Varghese explains: "They're not awake, their brain is still sleeping, they're just engaging in these complex behaviours. They might eat unusual foods and then go directly back to bed and have no recollection of it."
To diagnose SRED, you may need to do an overnight sleep study. This is called a polysomnogram, which charts your brain waves, heart beat, and breathing as you sleep. It also records how your arms and legs move. The best sleep study will also record your sleep on video and will record any unusual behaviours that occur during the night, helping to reveal if your eating binges are related to any other sleep disorder.
The disorder can be treated with medication, like anti-depressants, but this is not always necessary.
Doctors say that sometimes having better 'sleep hygiene' can help, like a strict sleep schedule, less computer or phone time, and keeping your bedroom dark and cool.