It’s not just exercise and eating better that I’ve had to focus on since my heart scare in 2024. One of the many things doctors and health experts had to teach me was how important sleep really is.
I’ve lived with an anxiety disorder most of my life. For decades, I believed it caused my insomnia. I couldn’t fall asleep and would lie awake for hours, but I still thought that broken sleep was enough.
I was too stubborn, or more honestly, too stupid, to ask for help. Looking back, I see I had it all wrong. And it finally caught up with me (deep sleep, it turns out, can affect heart health).
That’s why sleep is a focus for me now. Poor sleep played a part in my health issues, and I’ve learned just how much it affects both the body and the mind.
This is where “core sleep” and “deep sleep” come in.
Core sleep is the basic amount of sleep your body needs to get through the day. It’s usually the first 5 or 6 hours of the night and includes a bit of deep sleep and some REM sleep. This part of sleep helps with your energy, mood, and memory, and keeps your body going.
Deep sleep, also called slow-wave sleep, is a special part of the sleep cycle. It’s when your body fully relaxes and starts to heal. Your brain slows down, your muscles rest, and your body begins repairing itself. It helps your immune system, fixes tissues, balances hormones, and locks in memories.
Here are some facts I’ve learned about core and deep sleep that surprised me, and they show why both types of sleep matter so much for your physical and mental health.
1. Deep Sleep Helps Protect Your Heart, Brain, and Body
Fact: Not getting enough deep sleep can raise your risk of serious health problems, like heart disease, type 2 diabetes, Alzheimer’s, and other long-term conditions.
This was the fact that made me sit up and listen. I had ignored the issue for too long, thinking my sleep was fine as long as I got some rest. But deep sleep is different, it’s when your body does its best healing.
What helped me most was getting up and moving, even just 10–15 minute walks during the day. I found that a mix of light regular exercise and better late-night eating habits made it much easier to fall asleep.
I stopped eating big amounts of carbs and sugar at night. I also set a regular bedtime and wake-up time. These small changes made a big difference to me, and they added up fast.
In just one year, my sleep pattern has improved massively, and I only paid attention to it because of this terrifying fact.
Also Read: The 12 Best Foods for Heart Health That You Should Eat More Of
2. Deep Sleep Only Happens When Core Sleep Is Solid
Fact: Most adults need 6 to 8 hours of core sleep each night. But out of that, only about 1 to 2 hours is deep sleep, the most healing part of sleep.
This made me realize. If deep sleep only happens for a small part of the night, and you need solid core sleep to get there, then broken or choppy sleep just doesn’t cut it. Even if you sleep for enough total hours, it might not be helping your body the way you think.
Deep sleep is when your body repairs itself. Your brain slows down, your muscles rest, and your immune system gets stronger. But to get there, you need good sleep habits.
That means having a regular bedtime and wake-up time, a quiet and calm space to sleep, and avoiding things that wake you, or stop you from sleeping in the first place, are all essential to mental and physical health.
3. Core Sleep Gives You the Daily Boost You Need
While I’ve talked a lot about deep sleep, core sleep matters too, and it’s where most of your nightly rest happens.
Fact: Core sleep helps your body stay steady day to day. It gives you energy, supports your immune system, balances your hormones, and helps your brain work better. It also helps your body build and store memories and repair itself, even if it’s not doing the heavy healing of deep sleep.
Core sleep includes the lighter stages of non-REM sleep and some REM sleep. It’s not as deep, but it’s still important.
When you don’t get enough core sleep, it can affect your mood, memory, and ability to think clearly. It can leave you feeling foggy, low, or worn out, even if you think you slept “enough.”
So while deep sleep is where the body does its most powerful recovery work, core sleep is the foundation. You need both to feel and function your best.
4. Deep Sleep Is When the Body Does Its Best Work
The more I learned about deep sleep, the more I realized how powerful it is, especially for someone like me with heart health concerns.
During deep sleep, your brain waves slow down, your heart rate and blood pressure drop, and your muscles fully relax. This is also when your body releases growth hormone, which helps repair tissue, grow muscles, and refresh your cells.
Fact: Deep sleep plays a big role in keeping your hormones in check. It helps control cortisol, which is linked to stress; insulin, which manages your blood sugar; and leptin, which affects your appetite. It also strengthens your immune system by helping your body make more cytokines, tiny proteins that fight off infections and reduce inflammation.
So it’s not just your heart that benefits. Deep sleep helps your whole body heal, recover, and stay strong.
Also Read: 10 Fun Facts About the Mouth That Will Surprise You
5. Deep Sleep Helps Protect Your Brain as You Age
Fact: Deep sleep isn’t just about physical recovery; it plays a big role in memory, learning, and clear thinking.
This is when your brain processes what you’ve learned and stores it, helping you make sense of the day. It’s also the stage of sleep that’s hardest to wake up from. If you do get woken up during deep sleep, you often feel groggy or foggy for a while afterward.
As we get older, the amount of deep sleep we get naturally drops. But even though we may get less of it, deep sleep is still just as important, especially for brain health.
The more I write this, the more I see how many things I let slide, things I should have been watching to protect both my mental and physical health:
Dementia is a real issue in my family. My mom, her siblings, and my grandmother all had it. While not all dementia is passed down, it’s still something I should have been doing more to delay or possibly prevent.
And once again, this brings me back to sleep. Deep sleep helps clear out waste in the brain, supports memory, and keeps the mind sharper for longer. It’s one more reason why I now treat sleep as seriously as diet or exercise.