Not being able to sleep at night is something everyone has experienced. We often stay awake late for trivial reasons.

From worries like "What will happen at work tomorrow?" to feeling heavy-hearted over family or romantic issues, we toss and turn.

I've also stayed up very late on weekends watching dramas like "The Summer I Turned Pretty."

The problem arises when this happens not just for a day or two, but for a week, several weeks, or even months.

What doctors refer to at that time is 'sleep debt.'

Literally, it is the accumulation of the difference between the time I should be sleeping and the actual time I sleep.

If I sleep late for a day or two, it's not a big deal, but if I consistently sleep less, it accumulates like a debt in my body.

For example, if my body needs 8 hours of sleep a day but I only sleep 6 hours, I am accumulating a debt of 2 hours each day.

By Friday, it's as if I haven't slept for a whole day.

I remember working until 2-3 AM for several days due to escrow issues, and by the weekend, I felt dazed and was irritable over trivial matters.

That's the scary part of sleep debt.

Experts say that this sleep debt goes beyond mere fatigue and impacts our overall health.

It slows down brain response times, weakens concentration, and clouds decision-making abilities.

Moreover, it can negatively affect insulin regulation, inflammatory responses, and cardiovascular health, leading to bigger problems.

Long-term, it increases the risk of diseases like diabetes, hypertension, heart disease, and depression.

There are even studies suggesting that poor sleep after the age of 40 can reduce life expectancy.

What's even scarier is that lack of sleep changes our appetite.

Normally, we stop eating when we feel full, but in a sleep-deprived state, we crave sweets and carbohydrates more intensely.

Because we're tired, we tend to reach for sugary drinks, snacks, and bread. Ultimately, we gain weight, our immune system weakens, and we fall into a vicious cycle.

That's why doctors firmly state, "Sleep is not a luxury, but the foundation of health."

Here's an important question: Can we just catch up on sleep over the weekend?

I used to believe that 'sleeping in' on weekends would solve the problem, but experts say that's a misconception.

Even if you sleep a lot on weekends, you can't fully repay the sleep debt accumulated during the weekdays.

In fact, sleeping in on weekends can disrupt your biological rhythm, making Mondays even harder.

This phenomenon is commonly referred to as "social jet lag."

So what should we do? There are no short-term fixes.

The body cannot recover with just a day or two of extra sleep; it needs a consistent sleep schedule.

Doctors advise going to bed a little earlier than usual and maintaining this for several days or weeks to reset your body clock.

A short nap is fine, but it should be strategic so it doesn't interfere with your evening sleep.

Ultimately, the key is 'rhythm.' You need to go to bed and wake up at the same time every day.

Sleeping late and waking late on weekends will only add to your sleep debt, so it's best to avoid that.

The bedroom environment is also important. If it's too hot or bright, you won't be able to sleep deeply, so creating a cool, dark, and quiet environment is essential.

As I've hit my 40s, I definitely feel it. I used to be able to push through a night without sleep, but now it takes a long time to recover even after just one night of poor sleep.

If you ignore the signals your body sends, your health can completely deteriorate.

These days, I realize that what I lose by cutting back on sleep is far greater than what I gain.

In the end, sleep is an 'investment.' For both my present self and my future self, I must ensure I get 7-8 hours of sleep every day.

Money and time can be earned back, but health cannot.