But checking your phone before you fall asleep could be the reason that you're not losing weight, according to new research published in the journal PLOS One.
For the study, 19 people were randomly assigned either to three hours of blue-enriched light exposure (the same kind emitted from your phone of computer screen) right after waking up or just before they went to sleep.
In both cases exposure to bright light changed the participants' metabolic function by increasing their insulin levels which can in turn raise glucose levels. A rise in glucose can lead to weight gain, excess body fat and in some cases diabetes.
They also found that spending time on your screen before bedtime led to a higher peak in glucose levels (AKA blood sugar), than morning exposure. And over time, all that excess glucose can lead to excess body fat.
But the real issue that stands out from the study is how the bright light from your smartphone can disrupt your sleep pattern – pushing your metabolism out of whack.
Lack of sleep can have a huge affect on your metabolism. Talking to WebMD, Michael Breus, PhD, author of Beauty Sleep explains that when you're sleep deprived, your metabolism won't function properly.
Our internal clock (or circadian rhythm) works on a 24-hour cycle, and it tells us when to sleep and when to wake up. But sunlight, artificial light and temperature can mess that up, taking our metabolism along with it.
So if you constantly look at your smartphone before you drift off to sleep, this could affect your sleep pattern, causing a rise in glucose levels as well as weight gain.
Dr Craig Hudson, doctor, psychiatrist, author and creator of Zenbev, the 30 day to better sleep programme says, 'Darkness is essential for you to fall asleep and importantly, stay asleep.'
Darkness in a bedroom is picked up by receptors in your eyes, which sets in motion a process to release the sleep hormone melatonin, he explains.
'Even low amounts of ambient light, such as the glow from a mobile phone, iPad or other device such as a clock radio, will suppress the production of melatonin which will affect not only sleep but has other health consequences as well,' says Dr Hudson.
'If you are sleep-deprived through not getting enough sleep or good quality sleep, your metabolism will not function properly,' says Dr Craig Hudson.
'Exactly how lack of sleep affects our ability to lose weight has a lot to do with our nightly hormones. The two hormones that are key in this process are ghrelin and leptin. Ghrelin is the hormone that tells you when to eat, and when you are sleep-deprived, you have more ghrelin than Leptin, the hormone that tells you to stop eating. More ghrelin plus less leptin equals weight gain.' Dr Hudson explains.
Dr Mark Winwood, AXA PPP Healthcare's psychologist, says 'The portable nature of these devices means they can be used at bedtime and if that's the case the brain can interpret the light they emit to mean it's daytime, which can prevent a person from switching off and winding down for bedtime properly,'.
If you're a slave to your smartphone before you drift off to sleep, try having a bit of detox if you can! Or alternatively iPhones have a 'Night Shift' setting, which automatically adjusts the display to give off a warmer, less intrusive light.