In a TikTok video, Dr Rajan explains that if your partner snores or moves around too much while asleep, this will probably prevent you from entering REM (rapid eye movement) sleep - aka the deepest stage of a person's sleep cycle.
In an video shared with his almost five million TikTok followers, Dr Rajan, who works as a surgeon and is also a lecturer at the University of Sunderland in the UK, explained that not everybody will have the same type of sleep cycle, which means that one partner could end up chronically sleep-deprived, while the other is perfectly well-rested.
"Body temperature is also an issue here, as sharing a bed with someone naturally raises body heat, which could in turn lead to insufficient sleep."
Sleep divorce is trending
And that's why many couples are considering sleep divorce.
Sleep divorce is basically an arrangement between couples to sleep apart to improve their sleep hygiene – which could actually end up helping their relationship and their health.
According to Dr Erin Flynn-Evans, a consultant to the American Academy of Sleep Medicine, a sleep divorce is actually a really good idea.
"There are benefits for some partners to sleep separately," Flynn-Evans explained to CNBC.
"Studies demonstrate that when one bed partner has a sleep disorder it can negatively affect the other sleeper. For example, bed partners tend to wake up at the same time when one has insomnia.
"Similarly, when bed partners differ in chronotype, like when one is a night owl the other is an early bird, these differing sleep preferences can negatively impact both partners' sleep."
And it seems the idea of a sleep divorce is catching on – with the term now trending online.
On TikTok, there are currently more than 355,000 views for the hashtag #sleepdivorce.
Dr Karan explained: "One of the triggers you need to be able to fall asleep is the drop in core body temperature. Sharing a bed increases body heat so it'll take longer for you to fall asleep."