Did you have a rubbish sleep last night? Unfortunately, it may have done more than just make you feel a bit grumpy at work.
It turns out that not getting enough kip could actually be affecting your WEIGHT. Bad news for Netflix bingers, right?
A new video from BrainCraft - a YouTube series exploring psychology and neuroscience - explains (depressingly) how this works.
Apparently, upsetting the balanced community of microbes living in your gut can cause weight gain. And that's exactly what a lack of sleep does.
Not sure about the science behind this? Put simply, when this community - also known as your microbiome - is disrupted, it can affect your mood, stress levels and sleep.
As your microbiome is 'intertwined' with your sleep-wake cycle, it's connected to changes in your metabolism, which can lead to weight gain.
BrainCraft's Vanessa Hill says: 'Disrupting our body's internal clock can lead to cravings for unhealthy food and then eating unhealthy food messes with your appetite.
'Some researchers even think the bacteria in your gut are responsible for the calories you burn in your sleep.'
This is all because a poor night's sleep leads the body to continue its production of the stress hormone cortisol, which negatively affects the microbiome.
To prove this theory, Vanessa has given us an example of a study on mice.
Rodents that were fed a high-fat diet ended up becoming obese, because their diet had caused the microbes in their gut to change - and therefore their metabolisms.
This made them crave more high fat food, eat at the wrong times of day, have multiple lunches and indulge in midnight snacks.
In comparison, mice on a low-fat and high-fibre diet stayed lean.
Worried this could affect you? Watch the BrainCraft video below...