Why sleep matters

Chronic tiredness and fatigue is a precursor to all sorts of complications

Feb 02, 2025

“I never sleep more than a couple of hours a night.”
“Sleep is a waste of time.”
“Sleep is for losers.”
“I’ll sleep when I’m dead.”

I used to hear things like this all the time when I was an entrepreneur. LinkedIn and the like are full of people bragging about how little they sleep.1 As a society, we’ve made sleep something to be ashamed of: if you’re sleeping, you’re clearly not living your best life. And yet, 88% of us say we’re regularly fatigued. 13.5% of us say we’re permanently exhausted, to the point that tiredness actively impairs our ability to function.2

But sleep isn’t a waste of time. Far from it. It’s absolutely essential for our minds and bodies.3 A single night without sleep has immediate mental and physical effects. Several nights without sleep can effectively drive you insane. And chronic sleep deprivation will slowly but surely cause long-term damage.

The amount of sleep you require varies from person to person, depending on age, genetics, and many other factors. It’s not as simple as saying you should get eight hours a night, or seven, or whatever. But the vast majority of us aren’t getting as much sleep as we need, whether we’re aware of it or not. We’ve accustomed ourselves to managing on less than we need, often for years, and our natural state has become constant low-level tiredness.

Just ask yourself, when was the last time you woke up and felt fully refreshed, like a character in a romcom or a stock image on a wellness blog? Chances are, you don’t even remember what that feels like.

What sleep deprivation does to you

Sleep is when your body and brain perform their regular daily maintenance cycles. When you’re not devoting energy to anything else, damaged cells get repaired, neurotransmitter and hormone levels get reset, memories get processed and stored, your gut finishes digesting the food you ate earlier in the day, and so on. If you skimp on the maintenance and don’t give yourself enough time to finish the job, your performance will, inevitably, become impaired. Some of the effects of sleep deprivation will be noticeable immediately. Others take a while before they’re apparent.

Elevated levels of stress hormones: stress levels naturally decrease while you sleep. As your breathing rate and heart rate slows, it stimulates your parasympathetic nervous system to start eliminating cortisol, resetting everything back to normal. If you don’t get enough sleep, you wake up with a residue of cortisol in your body, which can build up over time to chronic stress.4 That can manifest itself in many forms, including the following…
More headaches and increased susceptibility to migraines: lack of sleep literally makes your brain hurt. A single night of missed sleep can cause a crippling headache that lasts all day. Long-term sleep deprivation can cause continuous low-level head pain, or break out into full-fledged migraine.
Mental fog, lack of motivation, impaired perception. and reduced attention span: after a single poor night’s sleep, you find it hard to focus and hard to concentrate. Routine tasks take longer and they take more effort - if you can manage to do them at all. Even simple jobs like doing the dishes can be too much. Trying to figure out a grocery list or respond to an email becomes a Herculean task. You end up lost in your own little world, half-asleep and oblivious to what’s going on around you. Even if you are unconsciously aware of things, your brain can’t process them properly. You may be vaguely aware that your dinner is burning on the stove, but your brain doesn’t necessarily make the leap to deciding you should get up and do something about it.5
Memory impairment: every part of your memory is affected. You lose track of what you’re doing because you can’t form short-term memories properly. You can’t recall things you know well because your long-term memory isn’t working. You can’t remember the right words, or people’s names. You forget the things you’re supposed to be doing today - or what you’re doing right now. Yesterday’s a blur because you couldn’t process yesterday’s memories properly overnight. And today’s going to be a blur too because today’s messed-up memories are going to get mixed up with the stuff that’s still waiting to be processed.6
Poor problem-solving: your performance on simple cognitive tasks will degrade. More complex tasks can become impossible. Missing just a couple of hours sleep can reduce exam performance by one or more grades: in professional situations, it can result in critical information being missed.7
Poor decision-making: you can’t focus, you can’t think straight, you can’t remember things, you’re irritable and impulsive…of course you’re going to make bad decisions. These can have far-reaching consequences, for yourself and others.
Irritability: when you get tired, you get grumpy. Your higher brain functions are suppressed, so you’re more reliant on the limbic system, which tends to treat everything as a threat. And all you want is just to be left alone to sleep, which causes…
Relationship issues: when you’re tired, you’re not pleasant to be around. This can drive people away, which causes feelings of isolation and stress, which can then cause even more sleepless nights.
Reduced libido: just to add insult to injury, and threaten your relationships even more, you lose interest in physical contact. Which, ironically, is one of the best things for dealing with sleeplessness, as it triggers oxytocin, serotonin, and dopamine which reduce stress and make it easier to sleep.
Depression: with all the above going on, it’s hardly surprising. Chronic sleeplessness can also trigger anxiety, lack of self-esteem, paranoia, PTSD and more.
Increased drug use: it’s not just cocaine, amphetamines, cannabis and ketamine though those are common enough, especially in high-pressure environments. When you’re tired, you’re more likely to rely on caffeine to wake you up, alcohol to help you prepare for sleep (which doesn’t actually work), and OTC or prescription medication to knock you out. While they can help in the short term under controlled conditions, in the long term, they actually impair your sleep.
Poor diet: when you’re tired, you’re more prone to grab whatever’s quickest and easiest. That usually means making unhealthy choices for the sake of convenience. This has a range of unwanted effects, including…
Increased weight: tiredness can be a major factor in obesity. When you’re sleep deprived, your body releases less leptin, the hormone that signals that you’ve had enough to eat. Instead, it releases ghrelin, which is an appetite stimulant, so you end up eating larger portions, and snacking more often.
Increased LDL cholesterol and reduced HDL cholesterol levels: this affects women more than men, for some reason. Lack of sleep affects the gene responsible for cholesterol transport, which can cause hypercholesterolemia, leading to a range of life-threatening conditions.8
Increased blood sugar levels: sleep deprivation causes your body to release less insulin after you eat, so glucose levels don’t drop as rapidly as they should. Eventually, this can cause diabetes.
Increased blood pressure: when you sleep, your blood pressure drops by up to 20%. If you don’t get enough sleep, it stays high, leading to hypertension. This can be exacerbated by a poor diet, which typically involves high levels of saturated fats, salts and sugars.9
Weakened immune system: if your body isn’t in good condition, it’s less able to fight off infection. But not only are you more susceptible to illness and disease, you’ll also suffer from…
Slower wound healing and disease recovery: there’s a reason your doctor tells you to get plenty of rest when you’re sick. While you’re asleep, your body can devote plenty of resources to recuperation, so you can recover quicker. But if you’re tired, you’ll sicken more easily, it’ll be more severe, and it’ll last longer.1011
Increased risk of accidents: usually caused by loss of balance, loss of digital dexterity, lowered reaction time, blurred vision, or micro-sleeps. You’re more likely to fall, drop things, bump into things, or injure yourself. And if you’re driving a car… well, driving after being awake for 24 hours is more dangerous than drunk driving. An hour of lost sleep slows your reaction by around half a second. That may not sound like much, but that’s 45 feet at 60mph, which can make the difference between braking in time and hitting the semi in front of you.12 In the US, roughly 6,000 people a year die through drowsy driving, compared to around 10,000 through drink and drugs.13
Inability to exercise: when you’re too tired to function properly, the last thing you feel like doing is pushing yourself physically. So your overall fitness declines, which causes a whole load more problems, such as…
Increased risk of sleep apnea, stroke, heart attacks, and dementia: yes, you can literally exhaust yourself to death. Your body literally becomes a wreck, until it gives up. Sleeping less than six hours per night raises your risk of premature death by 12%.14
Insomnia: well, ain’t that a bitch? To cap it all, the more tired you are, the harder it is to get proper sleep. Sleep deprivation messes with your Circadian rhythms, which affects melatonin production, which means you don’t get the right signals to tell your body to get into sleep mode. And then you stress about not sleeping, which makes it all worse, and it all turns into a horrendous downward spiral of exhaustion.

So, no, sleep is not a waste of time. Sleep is absolutely essential. There’s a reason why top athletes sleep a lot - it underpins their ability to achieve peak mental and physical performance.

“You can sleep when you’re dead,” is actually deadly advice.

Sleep - the miracle cure?

Well, no… and yes.

Sleep alone obviously can’t fix all your problems. But on the other hand, lack of sleep is probably at the root of many of them. Better sleep is a prerequisite for almost everything else.

If you can find a way to get more sleep - and better quality sleep, which is a whole different issue - you’ll put yourself in a good position to start making beneficial changes in many areas of your life, both physically and mentally.

I’ll start looking at how to do that in future posts. But the first step, as with so many other things in life, is to be aware of what sleep deprivation is doing to you and accept that it’s something that you need to address.

Unhack Your Brain

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