Why can't I sleep well? Keys, myths and advice from Dr. Estivill

By: Rene Z.Z. Published: 19 Jun 2025Updated: 24 Sep 2026Reading: 6 min

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Dr. Eduard Estivill visited René on ZZEN Talks, and today we tell you everything they talked about.

Dr. Estivill is one of the leading specialists in sleep medicine in Spain, and answers one of the most repeated questions in any medical consultation or conversation: why can't I sleep well?

Throughout the interview, the doctor debunks myths, explains key concepts and shares practical tools to understand and improve the quality of our rest. These are the most notable ideas from the episode.

Sleep, a repair workshop

“The first thing to understand is that sleep is a repair workshop.”

Dr. Estivill

Estivill starts with this phrase. For him, sleeping isn't a luxury or a reward for the day: it's a biological necessity that lets us repair everything we've used up during the day, both physically and mentally. And the amount of repair each person needs varies, especially according to age.

How many hours do I need to sleep

It depends on the life stage you're in:

Age	Hours of sleep	Why
Children aged 5	At least 11 hours	They move, learn and use energy constantly
Teenagers aged 16 to 17	About 9 hours	They're still learning and developing, with high demands
Adults	Between 7 and 8 hours	The key isn't just the number, but how you feel the next day

What he emphasises above all is that it's no good sleeping five hours from Monday to Friday and catching up on Saturday and Sunday. Because you recover something, yes, but not everything you've lost.

“The only way to know if you've slept well is to see how you are during the day.”

Dr. Estivill

If you've slept 6 hours but you feel in a good mood, focused, with energy and able to react normally, then that time has been enough for you. The problem is that many people believe they sleep what they need, but in reality they live dragging around a chronic tiredness that they already consider normal.

The sleep routine starts on waking

One of the most powerful concepts of the episode is the chronobiology of sleep. The process of sleeping well starts from the moment we open our eyes in the morning.

“Sleep is born when you open your eyes in the morning.”

Dr. Estivill

Throughout the day, the body accumulates signals that prepare the brain to rest at night. This includes:

Exposing yourself to sunlight, which regulates the biological clock.
Doing some physical activity, even if it's walking a kilometre a day.
Avoiding major stimulants, such as excess caffeine.
Reducing screens at night.
Having dinner early and disconnecting from work before sleep.

Therefore, sleeping well isn't something that's activated when you turn off the light. It's a process that's prepared throughout the day.

The mistake of thinking that sleeping little is for successful people

Dr. Estivill clearly criticises one of the most dangerous ideas on social media: that sleeping is for lazy people or that successful people sleep very little.

He states that even public figures who say they sleep little actually do it in bits or through compensatory naps. The body needs to sleep. And when it doesn't, it pays for it: lack of concentration, irritability, metabolic or cardiovascular diseases and cognitive deterioration.

And do sleep supplements work

Dr. Estivill is in favour of using natural supplements, such as ZZEN Sleep or Magnesium 7+, but only as support, and never as a substitute for proper habits. He even mentions that his daughter, Dr. Carla Estivill, is the creator of the three-layer melatonin, valerian and passionflower pills.

He also reminds us that there are more than 40 different causes of insomnia. Therefore, no supplement will work the same for everyone. Before turning to a product, it's essential to review lifestyle habits, stress levels and sleep hygiene and, if necessary, consult a specialist.

Because, as Dr. Estivill comments, if you drink 20 coffees a day, the sleep supplement will be of no use to you. You must accompany it with good habits, and the one that can help you with that is the ZZEN Challenge.

How to prepare quality sleep according to Estivill

These are Dr. Estivill's recommendations for improving the quality of rest realistically and without magic solutions:

Wake up at the same time every day.
Have a good, early breakfast.
Do moderate physical activity and get some sun.
Change small habits: get off one stop earlier and walk 10 or 15 minutes.
Have dinner early.
Disconnect from work at least two hours before going to bed.
Avoid screens and intense stimuli at night.

*Extra tip: of the whole list, the one that pays off most if you can only change one thing is the first. The time you wake up is what sets the clock for the whole day, including weekends.

And if you need it, you can rely on natural sleep supplements, always as a complement to these guidelines.

Sleeping well is a daily responsibility

Sleeping well isn't a matter of luck, or genetics, or age. It's a matter of respecting the body's rhythms, of knowing how sleep works and of applying daily habits that favour it. As Estivill states, it's not just about counting hours, but about knowing whether your repair workshop has worked.