What causes energy crashes? (And how to fix it)
- MJ Korthals
- 2 hours ago
- 6 min read
Few things are more frustrating than starting the day feeling reasonably productive, only to find yourself completely drained a few hours later.
One moment you are focused, motivated, and getting things done. The next, you are reaching for another coffee, craving something sweet, struggling to concentrate, or wondering why your brain suddenly feels like it has slowed down.
Most people experience energy crashes at some point, but because they are so common, they are often treated as a normal part of modern life. The afternoon slump. The post-lunch crash. The mid-morning dip. The evening exhaustion that arrives long before bedtime. These experiences have become so familiar that many people assume they are simply unavoidable.
The reality is that energy crashes are not random. They are usually the result of underlying physiological processes that affect how the body produces, regulates, and distributes energy throughout the day. Whilst occasional fluctuations are completely normal, repeated crashes are often a sign that one or more systems inside the body are struggling to keep up with demand.
When energy becomes unstable, the body is usually trying to tell you something.
And the good news is that once you understand what is happening underneath the surface, many energy crashes become far easier to prevent.
What Is an Energy Crash (Under the Hood)?
At its simplest, an energy crash occurs when the body's ability to meet energy demand temporarily falls behind what is being asked of it. The result is a noticeable drop in physical energy, mental clarity, concentration, motivation, or alertness. Sometimes this feels like overwhelming tiredness. Sometimes it feels like brain fog. Sometimes it simply feels like your battery has suddenly emptied.
The important thing to understand is that energy is not produced by a single system. It is the result of multiple systems working together constantly. Sleep, nutrition, blood sugar regulation, hormones, stress responses, nervous system activity, hydration, movement, and recovery all play a role in determining how energised you feel from one hour to the next.
When these systems are working well, energy tends to feel relatively stable. Whilst you may experience natural fluctuations throughout the day they are generally manageable and completely normal. When one or more systems become disrupted however, the body's ability to regulate energy becomes less predictable.
This is why energy crashes often involve more than simply feeling tired. Many people describe:
Brain fog
Poor concentration
Irritability
Cravings
Low motivation
Feeling flat
Difficulty making decisions
The body is not necessarily "running out" of energy. More often than not, energy regulation itself has become disrupted. And when that happens, the symptoms can feel surprisingly powerful.
The Modern World and Constant Energy Demand
One of the biggest reasons energy crashes have become so common is that modern life creates enormous demand whilst offering very little genuine recovery.
Humans evolved in environments that contained periods of activity followed by periods of rest. Today, many people spend their entire day moving from one demand to the next without ever truly switching off.
The average day now includes work demands, notifications, emails, messages, social media, decision-making, financial pressures, family responsibilities, artificial lighting, constant information consumption, and ongoing mental stimulation. Even when sitting still physically, the brain may be processing hundreds of inputs throughout the day.
The body is remarkably adaptable, which is why people can often tolerate this lifestyle for extended periods. The problem is that adaptation is not the same thing as optimisation.
The body can compensate for poor habits temporarily, but eventually recovery begins falling behind demand. What makes this particularly challenging is that many people no longer recognise how overloaded they have become.
The lifestyle itself feels normal. The exhaustion feels normal. The crashes feel normal. But biologically, the body is often working incredibly hard simply to keep up.
Think about a typical day:
Wake up and check your phone
Rush through the morning
Sit under artificial light
Work under constant cognitive demand
Skip breaks
Drink caffeine to push through
Scroll in the evening
Sleep poorly
Repeat. Day after day. Week after week.
The body can do this. But it pays a price eventually. And that price often appears as unstable energy.
5 Things That Cause Energy Crashes
1. Poor Blood Sugar Regulation
One of the most common causes of energy crashes is unstable blood sugar regulation. When meals are heavily based around highly processed foods, sugary snacks, or quick-energy options, blood sugar can rise rapidly and then fall just as quickly afterwards.
This creates what is often called the blood sugar rollercoaster (read our blog on this here). Energy rises sharply, feels great for a short period, and then drops away. Hunger returns. Cravings appear. Concentration declines. The cycle repeats.
Many people experience this without realising what is happening underneath the surface. The pattern often looks something like:
highly processed food → energy spike → energy crash → cravings → repeat
2. Poor Sleep
Sleep remains one of the most powerful drivers of daytime energy. During sleep, the body is repairing tissues, regulating hormones, supporting the immune system, consolidating memories, and recovering from the demands of the previous day. When sleep quality drops, every other energy system becomes harder to regulate.
Blood sugar becomes less stable. Stress tolerance falls. Cravings increase. Recovery suffers.
This is one reason poor sleep often creates energy crashes that no amount of caffeine seems capable of fixing.
The body may be awake. But it is not fully recovered.
3. Chronic Stress
Stress is often misunderstood as a purely emotional experience. In reality, stress is a biological process that requires energy and effects almost every system in the human body. Every time the body activates a stress response, resources are diverted toward survival, alertness, and performance.
Initially this can feel energising. You feel switched on, focused, alert. Exactly as nature has intended. But stress-driven energy is not the same thing as sustainable energy.
Eventually the nervous system becomes overloaded, recovery declines, and energy crashes become increasingly common. Many people spend so long operating in "go mode" that they do not realise how exhausted they have become until the body starts forcing them to slow down.
4. Excessive Caffeine Dependence
Caffeine can be a useful tool when used appropriately. The issue is that many people use caffeine to compensate for poor sleep, chronic stress, inadequate nutrition, or general exhaustion. This creates a situation where caffeine becomes the solution to problems that caffeine itself cannot solve.
The result often looks like:
poor sleep → low energy → more caffeine → worse sleep → lower energy
Over time, people become increasingly reliant on stimulation whilst the underlying causes remain unchanged. And this is a dangerous combination when it comes to health, energy and vitality.
5. Under-Recovery
Modern culture celebrates productivity, achievement, and constantly being busy. What it rarely celebrates is recovery. The problem is that the human body requires both. Because recovery is where adaptation occurs, where repair happens, where energy is restored.
Without sufficient recovery, the body gradually accumulates fatigue across multiple systems. Sleep quality declines, stress rises, motivation drops, and energy becomes less reliable. This is why some people feel permanently tired despite doing everything they believe they should be doing.
They are spending energy. But not replenishing it.
Ways To Improve Energy (And Prevent Crashes)
The good news is that most energy crashes can be improved by supporting the same foundational systems we have already explored throughout this blog series. The body generally does not need complicated solutions. More often, it needs consistent support for the systems responsible for creating stable energy in the first place.
This is where many people overcomplicate things. They search for supplements, stimulants, shortcuts, or quick fixes when the biggest wins are often found in the fundamentals.
The foundations matter more than people realise.
If you have already read some of our previous articles, you will probably notice a familiar pattern emerging. Focus on:
These may not be the most exciting solutions. But biologically, they are incredibly powerful.
Because energy crashes rarely exist in isolation. They are usually symptoms of larger patterns, unfolding over time. Improving these patterns and habits improves energy dramatically.
And remember: The goal is not to feel "high energy" all the time. The goal is stable, reliable energy. Energy that lasts.
Closing
Energy crashes have become incredibly common, but they are not something we should simply accept as normal. Whilst occasional dips in energy are part of being human, repeated crashes often signal that the body's energy systems are struggling to keep pace with modern demands.
Most energy crashes are not caused by a lack of willpower. They are driven by physiology.
By poor sleep. By unstable blood sugar. By chronic stress. By overstimulation. By insufficient recovery.
And thankfully, these are all things that can be improved. More often, it is about rebuilding the foundations that allow the body to produce energy naturally in the first place.
Because real energy is not created through constant stimulation. It is created through recovery, nourishment, rhythm, and balance.
And if this resonated with you – then you recognise that fad / extreme approaches rarely work. It is about building sustainable habits over the long term that really drive better health, sleep, energy and vitality.
That’s exactly why I created a FREE Daily Energy Blueprint Guide — a practical system to help you stabilise your energy using food, recovery, and daily habits that actually work.
You can download your free guide – here
And you can access the rest of our blog posts on our blog home page - here
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