Why You Sleep Badly, Then Get Ill and Have No Energy - It's Not a Coincidence

Have you ever heard the phrase: "Get some sleep and you'll feel better"? It's not just a comforting throwaway line from your grandma. It's an actual biological truth. The problem is that most of us treat sleep as an optional add-on to life - something that can be cut short to watch one more episode or finish a project.

And then we wonder why we're catching our third cold of the year, why we're tired from the moment we wake up despite drinking coffee, or why we can't lose weight despite dieting. Spoiler alert: sleep has far more to do with all of this than you might think.

What happens when you sleep? (Hint: much more than you think)

When you go to bed, your body doesn't shut down like a computer. Quite the opposite - it fires up an entire command centre for regenerative processes. Sleep isn't downtime. It's intensive behind-the-scenes work whose results you see (or don't see) the next day.

And we're not talking about some esoteric "energy cleansing" - we're talking about concrete physiological processes you can measure, test, and feel. But only if you give your body enough time.

Sleep and immunity - why do we keep getting ill in winter?

Anna, 29, works in an office as an accountant. Every winter she goes through at least 3-4 infections. Runny nose, cough, sore throat, runny nose again. She supplements with vitamin D, vitamin C, drinks ginger tea. Nothing helps. She finally went to an immunologist. The diagnosis? "How much do you sleep?" "Well... 5-6 hours." "Then start with that."

Anna rolled her eyes. But she tried it. She started going to bed earlier, paying attention to regularity. After three months she got through the entire flu season without a single illness. For the first time in years.

How does sleep support the immune system?

When you sleep, your immune system works at full capacity. The production of white blood cells, antibodies, and cytokines - proteins that fight infections - peaks at night.

Studies show something alarming: people who sleep less than 6 hours per night are four times more likely to catch a cold than those who sleep 7-8 hours. Four times. That's more than most dietary supplements can offer.

What happens when you don't sleep enough?

• Antibody production drops - your body doesn't have time to produce enough "soldiers" to fight pathogens
• Cortisol levels rise (the stress hormone) - which further weakens immunity
• Inflammatory processes intensify - meaning even a minor infection can develop into something more serious
• Vaccines work less effectively - yes, if you're not sleeping enough, even a flu jab may be less effective

Here's something interesting: a single night without sleep can reduce the activity of NK cells (natural killers) - special immune cells that kill viruses and cancer cells - by as much as 70%. One night.

Why do you feel sleepy when you're ill?

Have you ever wondered why when you have a cold, you can sleep 12 hours a day and still feel tired? It's not laziness. It's your immune system sending signals to your brain: "Hey, lie down and sleep, we've got work to do."

Sleep during illness is a form of therapy. The body uses energy that you'd normally spend on movement, thinking, and digestion to fight the infection instead. That's precisely why when we're ill, we shouldn't drag ourselves to work. Treatment isn't just about medication - it's primarily about rest.

Sleep and hormones - why you gain weight despite dieting

Now we're entering territory that will blow your mind. Maybe not literally, but it will certainly change your approach to sleep.

Remember Mark, the colleague from the sales department? He started going to the gym, went on a diet, counted calories obsessively. Three months - zero results. The weight stayed the same. Frustration grew. Finally, his trainer asked: "How much do you sleep?" "4-5 hours, I have to get up early." The trainer sighed. "Start with sleep. Then we'll get back to training."

Mark thought it was nonsense. But he tried. After a month of regular sleep (7-8 hours), he lost 4 kg. Without changing his diet or workout.

Leptin and ghrelin - hormones you need to know about

Imagine two hormones that control your feelings of hunger and satiety:

• Leptin - says: "I'm full, I don't need more food"
• Ghrelin - says: "I'm hungry, give me something to eat"

When you sleep too little, leptin levels drop (you feel less satisfied) and ghrelin levels rise (you feel hungrier). This isn't a matter of willpower. It's biochemistry.

Studies show that after a single night of 4-5 hours' sleep:

• Leptin drops by about 18%
• Ghrelin rises by about 28%
• Appetite for sweets and carbohydrates increases by 33-45%

That's why after a sleepless night you crave pizza, sweets, and everything calorific. It's not your fault. It's your hormones throwing a party.

Insulin and diabetes risk

Insulin is the hormone responsible for regulating blood sugar levels. When you don't sleep enough, your cells become less sensitive to insulin - a state called "insulin resistance." What does this mean? That your body needs more insulin to process sugar.

In the long run, this leads to:

• Increased risk of type 2 diabetes
• Greater fat accumulation (especially around the belly)
• Problems with carbohydrate metabolism

One study found that people who regularly sleep less than 6 hours per night have nearly twice the risk of developing type 2 diabetes compared to those who sleep 7-8 hours.

Cortisol - the stress hormone that ruins your body

Cortisol is a hormone that in natural doses is your friend - it helps you wake up in the morning, gives you energy to function. The problem appears when its level is constantly elevated.

Sleep deprivation causes cortisol to remain high throughout the day and night. The effects?

• Belly fat accumulation
• Weakened immune system
• Problems with memory and concentration
• Increased emotional tension and anxiety
• Sleep problems (a vicious cycle)

If you constantly feel "on edge," nervous, have trouble concentrating - before reaching for a calming supplement, check whether you're simply not sleeping enough.

Testosterone, oestrogen, and other sex hormones

In men: sleep deprivation lowers testosterone levels. One study found that men who slept 5 hours for a week had testosterone levels 10-15% lower than before the experiment. This can mean:

• Decreased libido
• Difficulty building muscle
• Reduced energy and motivation
• Fertility problems

In women: chronic sleep deprivation disrupts the menstrual cycle, affects oestrogen and progesterone levels, which can lead to:

• Irregular periods
• Worsened PMS symptoms
• Fertility problems
• Poorer skin quality

Growth hormone - not just for children

Growth hormone (GH) is produced mainly during sleep, particularly during the deep sleep phase. In adults, it's responsible for:

• Tissue and muscle regeneration
• Fat metabolism
• Bone density
• Healthy skin

Athletes and gym-goers know that sleep is when muscles are built. Without enough sleep, there's no recovery. Without recovery - there's no progress.

Sleep and energy - why you're tired all the time

OK, this seems the most obvious. Little sleep = you're tired. But there are more details worth knowing.

Mitochondria and energy production

Your cells contain small "power plants" called mitochondria. They produce ATP - the molecule that's the universal "energy currency" in the body. Everything you do - from blinking to running - requires ATP.

When you sleep, mitochondria have time for regeneration and repair. When you don't sleep enough, mitochondria work less efficiently. The result? Lower energy production = greater fatigue.

Why does coffee stop working?

You know that feeling when you drink your third coffee of the day and still feel like a zombie? It's not the coffee's fault. It's the fault of sleep deprivation.

Caffeine blocks adenosine receptors - a compound that signals your brain that you're tired. But caffeine doesn't remove adenosine - it just masks it. When the caffeine effect wears off, all the accumulated adenosine hits at once. That's why you feel the "crash."

And what happens when you're chronically sleep-deprived? Adenosine builds up like a debt. And no coffee will sort that out.

Concentration, memory, and cognitive function

After a sleepless night, your brain works worse than after drinking alcohol. Studies show that after 17 hours without sleep, your cognitive functions are comparable to having a blood alcohol level of about 0.05%.

After 24 hours without sleep? That's like being at 0.1%.

When you regularly don't sleep enough:

• Your attention drops - you make more mistakes
• Reactions are slower - particularly dangerous when driving
• Short-term memory falters - you forget what you wanted to say 5 seconds ago
• The decision-making process is impaired - you choose worse options

That's why "sleeping on it" isn't just an idiom - it's literally the best way to find a solution. During sleep, the brain consolidates memories, connects facts, and builds new neural connections.

How much sleep do you really need?

"5 hours is enough for me" - I hear this regularly. Usually from people who look like the walking dead.

Statistically, about 1-3% of the population are so-called "short sleepers" - people who genuinely only need 5-6 hours of sleep. The rest of us? We need more.

Recommendations by age:

• Adults (18-64): 7-9 hours
• Seniors (65+): 7-8 hours
• Teenagers (14-17): 8-10 hours
• School-age children (6-13): 9-11 hours

But these are averages. The best way to find out how much you need?

The holiday test

For a week of holidays (ideally the second week, once you've recovered from the stress), go to bed at the same time and allow yourself to wake up naturally - without an alarm. After a few days, your body will have paid off its "sleep debt" and establish its natural rhythm.

If you wake up after 8 hours feeling fresh - that's how much you need. If after 9 - that's fine too. Accept it and stop fighting your own biology.

What can you do to sleep better?

Right, you know the theory. Time for practice. Not everyone has the luxury of sleeping 9 hours a day. But everyone can improve sleep quality.

1. Regular hours - yes, even at the weekend

Your body loves routines. When you go to bed and get up at the same time (even at weekends), your circadian rhythm stabilises. Melatonin production starts at a predictable time. You wake up more rested in the morning.

2. Darken the bedroom

Even small light sources (electronic LEDs, street light) can disrupt melatonin production. Blackout curtains cost €15-35 and can completely transform your sleep.

3. Temperature matters

The ideal sleeping temperature is 16-19°C (61-66°F). It may seem cold, but under the duvet you'll be perfectly comfortable. The body needs to lower its temperature to fall asleep - help it out.

4. Avoid screens before bed

Blue light from phones, tablets, and computers tricks the brain into thinking it's daytime. The result? Delayed melatonin production. If you must use screens in the evening - turn on night mode or put on blue light blocking glasses (€8-25).

5. Limit caffeine in the afternoon

Caffeine has a half-life of about 5-6 hours. Coffee drunk at 4:00 PM is still circulating in your system at 10:00 PM. If you have trouble falling asleep - move your last coffee to 2:00 PM and see if it helps.

6. Exercise, but not before bed

Regular physical activity improves sleep quality. But intense exercise 2-3 hours before bed can make falling asleep harder. Best to exercise in the morning or afternoon.

7. Evening routine

Your brain needs a signal that bedtime is approaching. Create a routine:

• Turn off phone notifications at 9:00 PM
• Read for 10-15 minutes (a paper book, not a tablet)
• Do calm breathing exercises (4 seconds inhale, 7 seconds hold, 8 seconds exhale)

What about melatonin and other supplements?

Melatonin can help in short-term situations (jet lag, shift work, occasional insomnia). But it's not a magic solution for chronic sleep deprivation.

In many European countries, melatonin up to 1 mg is available over the counter (prices: €4-12). Higher doses may require a prescription. But before you reach for a supplement, try improving your sleep hygiene first. Supplements should be a last resort, not the first choice.

Remember: Melatonin is not a sleeping pill. It's a hormone that regulates the circadian rhythm. It doesn't put you to sleep - it tells the body that it's time for sleep. The difference is enormous.

If you're considering supplementation - consult a doctor or pharmacist, especially if you take other medications.

When to see a doctor?

If despite all your efforts, sleep problems persist for more than 3 months and affect your daily functioning - it's time to see a specialist.

Warning signs:

• Snoring with breathing pauses (could be sleep apnoea - a serious condition)
• Constant tiredness despite 7-8 hours of sleep
• Difficulty falling or staying asleep most nights of the week
• Restless leg movements at night (restless leg syndrome)
• Sleep doesn't bring a feeling of rest

Don't be a hero. Chronic insomnia isn't a character weakness - it's a medical problem that requires help.

Summary: sleep is not a luxury, it's a necessity

Sleep supports the immune system - people who sleep less than 6 hours are 4x more susceptible to infections

Sleep regulates hormones - it affects weight (leptin, ghrelin), metabolism (insulin), stress (cortisol), and sex hormones

Sleep provides energy - it regenerates mitochondria, consolidates memory, improves concentration and decision-making

Most adults need 7-9 hours of sleep - this isn't a luxury, it's a biological necessity

Quality matters - regular hours, darkness, a cool bedroom, and limiting screens can dramatically improve sleep

Supplements are a last resort - improve your sleep hygiene first, then consider melatonin (after consulting a pharmacist/doctor)

If you want to compare prices for sleep-supporting supplements - use CheaperForDrug. Type "melatonin," "magnesium glycinate," or "ashwagandha" and see which pharmacy offers the best price. Sometimes the difference amounts to several euros.

Disclaimer

This information is educational in nature and does not constitute medical advice. If you have chronic sleep problems, take medications, or have chronic conditions, consult a doctor before changing habits or starting supplementation. Some sleep disorders (e.g. sleep apnoea) require professional diagnosis and treatment.

And remember: If the only thing you do after reading this article is go to bed an hour earlier - that's already a huge success. Your body, mind, and immune system will thank you. And if you need supplements - check prices on CheaperForDrug and save on what truly matters.