Why Am I So Tired?

We tend to use tiredness, sleepiness and fatigue interchangeably, but they aren’t quite the same experience.

Sleepiness is the feeling that you need to sleep. Your eyelids are heavy, you’re yawning and, given the opportunity, you could probably lie down and drift off.

Fatigue can feel very different. You may not feel sleepy at all, but instead feel physically weak, heavy or lacking in stamina. Your brain may feel as though it has stopped cooperating, or perhaps everything simply requires far more effort and motivation than it once did.

You may experience several of these at the same time, but getting more specific about what “tired” actually feels like to you is a useful place to start.

This is one of the questions I often ask because the answer can tell us quite a lot.

If you hit a wall every afternoon and have the opportunity to take a nap, how do you feel when you wake up? If half an hour of sleep leaves you noticeably refreshed, sleep itself becomes a more interesting part of the picture.

Perhaps you simply aren’t getting enough. But it is also possible to spend eight hours in bed without getting eight hours of restorative sleep. Sleep can be disrupted by things like sleep apnoea, pain, hormonal changes, night sweats, alcohol or frequent waking, sometimes without you realising how fragmented it has become.

Another useful question is what happens when you don’t have to set an alarm.

If you normally wake at 6am feeling exhausted but sleep for another two hours on a weekend or holiday and wake feeling considerably better, your usual routine may simply not be allowing enough sleep for your individual needs.

If, on the other hand, it makes little difference whether you sleep for six hours, eight hours or ten, and even a long nap leaves you just as exhausted, it makes sense to look beyond simply needing more rest.

We often talk about energy as though there is a battery somewhere inside us that we run down during the day and recharge while we sleep. Biologically, it is much more complicated.

Food provides fuel and nutrients, which have to be digested and absorbed before they can be used. Oxygen and nutrients need to reach your tissues, and inside your cells, mitochondria help convert fuel into ATP, the form of energy your cells can actually use.

Hormones help regulate how energy is produced and used, while your nervous and immune systems can influence where that energy is directed and how readily it is spent.

So when you say, “I have no energy”, there are many different places where the system could be struggling. The challenge is working out where the bottleneck might be.

Sometimes it is worth starting with the basics: are you giving your body enough fuel and the right raw materials for what you’re asking it to do?

Carbohydrates are broken down into glucose, which can be used to produce ATP, with some stored as glycogen in your liver and muscles for later use. Your body can also use fat for energy and make glucose when carbohydrate intake is low, so this isn’t about suggesting everyone needs a high-carbohydrate diet.

Sometimes, however, people end up eating considerably less carbohydrate, or simply less food overall, than they realise, particularly after gradually restricting foods because of gut symptoms, blood glucose concerns or weight loss.

This can become noticeable with exercise. If you are training regularly without adequately replacing the fuel you have used, you may get through the workout reasonably well but feel depleted later or find that you aren’t recovering properly between sessions.

Fuel is only part of the picture. Iron is needed for oxygen transport, while B vitamins, magnesium and other nutrients are involved in turning food into usable energy. Those nutrients also have to be adequately digested and absorbed.

The useful question isn’t simply whether you eat a “healthy” diet. It is whether your body has enough fuel and raw materials available for the demands you are placing on it.

The timing of your fatigue can provide another useful clue.

Perhaps you wake exhausted but gradually improve as the day goes on. Maybe you wake feeling reasonably well but fade badly in the afternoon, become overwhelmingly sleepy after eating, or function all day only to collapse when you get home.

If you become very sleepy after meals, notice what you ate and whether the same thing happens every time. If you wake every morning feeling as though you haven’t slept, sleep quality deserves closer attention. If your energy changes alongside your menstrual cycle, or changed significantly during perimenopause, hormones may be part of the picture.

Rather than simply noticing that you’re tired, start noticing when you’re tired.

Think about how you feel on a normal working day compared with a weekend, or after you’ve been away from your usual routine for several days.

Perhaps you feel exhausted all week but noticeably better after a few days on holiday. That doesn’t mean your fatigue is “just stress”. Many things may have changed at once.

You may be sleeping longer, spending more time outside, moving differently or resting more. You may be eating differently, you’re not commuting, and there may be fewer deadlines, decisions and demands on your attention.

If your energy improves, what matters is that your energy is capable of changing when something about your circumstances changes. You can then start thinking about what is different.

The opposite is useful too. If you can take two weeks off, sleep as much as you want and remove most of your usual demands but still feel every bit as exhausted, that is also important information.

Exercise gives us another useful window into how your energy behaves.

Perhaps you can exercise reasonably well at the time but completely crash several hours later. Maybe you feel disproportionately exhausted the following day, or even a relatively small amount of activity now requires much longer recovery than it once did.

For other people, movement has almost the opposite effect. A walk clears their head, their energy improves and they feel more alert afterwards.

If you exercise regularly, it is also worth noticing whether you are adequately refuelling afterwards. Sometimes feeling depleted later is at least partly related to not replacing the energy you have just used.

The important clue isn’t simply whether you exercise. It is what happens to your energy when you do.

Energy and mood can be difficult to separate because the relationship can work in both directions.

If you’ve been exhausted for months, it is hardly surprising if you start to feel flat. Things you used to enjoy may begin to feel like effort simply because you don’t have the capacity you once had.

At the same time, low mood, prolonged stress and anxiety can affect sleep, appetite, concentration, movement and motivation, all of which can influence energy. Sometimes the same underlying factors may be contributing to both.

One interesting thing to notice is what happens when there is something you genuinely want to do. Perhaps you’ve felt exhausted all day, but an invitation you’re genuinely excited about suddenly brings some energy back. Or perhaps you desperately want to go, but physically you simply cannot manage it.

There is a meaningful difference between “I don’t feel like doing anything” and “I really want to do this, but my body cannot manage it.”

Sometimes fatigue isn’t simply a problem of not making enough energy. Your body may have competing demands for it.

Think about how you feel when you have influenza. You want to lie down, your motivation disappears, your thinking may slow and you feel profoundly tired. Immune activation changes metabolism and nervous-system signalling as your body shifts resources towards dealing with a threat.

Usually this is temporary, but immune activation and inflammation can also be more persistent, which is one reason fatigue can accompany inflammatory and autoimmune conditions, some gut problems and the aftermath of certain infections.

Your body can also become more economical with energy when resources are scarce or physiological demands are high. Hormones, including thyroid hormones, help regulate metabolic rate and influence how readily energy is spent.

Sometimes, therefore, the question isn’t only whether your body can make energy. It is also what else your body may be dealing with and how that is changing the way energy is used.

Of all the questions you can ask about fatigue, this may be one of the most useful.

Were you always someone who needed a lot of sleep, or can you remember a time when your energy was completely different?

Perhaps you were fine until an infection. Maybe your energy changed when your periods became heavier, after pregnancy, alongside digestive problems or during perimenopause. Or perhaps there was no obvious event, but looking back, you realise the decline has been happening gradually for several years.

The timing doesn’t automatically reveal the cause, but it can dramatically change where you start looking.

If something changed, what else was happening around the same time?

If you’ve spent months or years thinking simply, “I’m so tired”, try getting more curious about the pattern.

You don't need to diagnose yourself from the answers. The purpose is to notice patterns that may have been hidden inside the much broader feeling of simply being tired. 

You might realise that you feel dramatically better whenever you sleep without an alarm, or that your energy reliably disappears after lunch. Perhaps exercise makes you feel better rather than worse, or you notice that even on holiday, with plenty of sleep and very few demands, you feel exactly the same. 

Maybe the biggest clue is that you can pinpoint almost exactly when your energy changed. 

All of that tells you much more than simply "I'm tired all the time." 

Fatigue tells us what you are experiencing. The way your fatigue behaves can start to give us clues about why.