You aren't the only grown-up who struggles to have a lie-in.
Now, sleep experts have revealed exactly why your habits as a teenager are a thing of the past.
After a long week of work, the idea of having a lazy lie-in sounds great, but as we get older, many of us struggle to stay in bed.
The stereotypical teenager who needs to be woken up by their parents - or by a bucket of water - is long gone.
Well, according to experts, there happens to be two reasons why you wake up earlier as you get older.
It's to do with your brain and your eyes.
“The wiring of the brain is likely not sensing ... and responding to the inputs as well as it should because it’s an ageing brain,” Dr. Sairam Parthasarathy, the director of the Center for Sleep and Circadian Sciences at the University of Arizona Health Sciences, told HuffPost.
“These are all what we call time givers, or they give time to the brain.”
So what this means is that a younger person's brain is able to connect the dots better than an older person.
An inability to sense 'time cues', i.e. when to wake up, when to lie in, has a big impact on your decision making.
“Like most of the things that change with age, there’s not just one reason, and they are all interconnected,” said Cindy Lustig, a professor of psychology at the University of Michigan.
Your eyes are also equally as important.
“Interestingly, one of [the reasons] seems to be that the vision changes that come with age reduce the intensity of the degree of light stimulation that our brain receives, which plays an important role in ‘setting’ our circadian clock and keeping it on track.”
Parthasarathy added: “If there’s cataracts, the evening light doesn’t go into the eyes as much, so, according to the brain, sunset is earlier than when it actually set.”
Keep your blinds shut folks.
Now, our parents are always telling us how important it is to get our 'eight hours' of sleep per night, and they might just have a point.
Doctor Dan Friederich has warned us of the potentially deadly consequences of having between four and five hours of sleep.
"Do you think that you can survive on only four to five hours of sleep every night?" Dr Friederich asks his followers.
The award-winning eye care doctor from St. Louis, Missouri, insists that not getting enough sleep could lead to an 'early death'.
"And so studies have shown again and again that the optimal amount of sleep is between six and eight hours a night, preferably at least seven," he explained in a now-viral video posted on his TikTok page.
"If you go more than nine hours it's also bad for your health. But sleeping less than five is the worst thing you could possibly be doing.
"Increased mortality all across the board, cardiovascular disease, all types of diseases are associated with sleeping that little."
Now and again, your parents might be telling the truth.