How to Increase Energy During the Day? 10 Science-Backed Ways

Chronic daytime fatigue usually has more than one cause at once, yet popular guides treat it as if a single change — more coffee, one more supplement — should solve it. In practice, it's worth separating two categories of intervention that we deliberately keep together in this article, but clearly label: lifestyle habits you can implement on your own starting today, and signals that a drop in energy might have a specific medical cause requiring a blood test, not another cup of coffee.

This distinction matters in practice: someone who spends months trying to "boost their energy" with morning coffee, cold showers, and motivational podcasts, while the real cause is undiagnosed hypothyroidism or iron deficiency, wastes time and deepens their frustration. That's why the first seven items on this list are about lifestyle, and the last three — deliberately — are about when it's worth getting a simple blood test instead of adopting another habit.

This is the most obvious item on this list, but it earns first place because without it, the other nine methods work much less well. Insufficient sleep duration or quality is one of the most common, best-documented causes of reduced daytime energy — and the subjective feeling of "I got enough sleep" can be unreliable, especially with chronic, partial sleep deprivation that's easy to get used to without fully realizing the loss of performance.

Rather than repeat general recommendations here, we point you to our detailed article on twelve ways to improve sleep quality, where each element — regularity, light, temperature, caffeine — is covered separately with concrete studies. We also cover the role of sleep more broadly in our knowledge-base entry on sleep.

Beyond its effect on sleep itself (covered in detail in the article linked above), bright daylight also has a direct, acute effect on alertness and the subjective sense of energy during the day — this is the basis for light therapy used clinically for seasonal mood disorders and for regulating circadian rhythm in shift workers.

In practice, this means a mid-afternoon energy dip is partly an effect of spending most of the day in a dimly lit indoor space, not solely a matter of physical tiredness or lack of sleep. A short walk outside during the day — ideally in the first half of the day — is a cheap intervention that combines light exposure with the physical activity covered in the next item.

"I'm too tired to exercise" sounds logical, but the data suggests this often works the other way around: regular physical activity is associated with higher, not lower, daytime energy. The largest meta-analysis in this field, however, paints a more nuanced picture than the popular slogan "movement equals energy" suggests.

Feeling drowsy and losing energy 1-2 hours after a large meal high in simple sugars — the so-called "post-lunch dip" — is a real, well-described phenomenon in the literature, though its mechanism is more complex than just "blood sugar swings," and includes a natural, circadian dip in alertness in the early afternoon that's independent of eating.

Studies comparing high- and low-glycemic-index meals show a mixed, context-dependent picture: some studies point to a more favorable, more stable attention and memory profile after meals that cause a slower, more gradual rise in blood glucose, while others, especially with a short post-meal observation window, show no significant difference. Rather than citing a single, uncertain percentage figure, it's more honest to say: meals combining protein, fiber and complex carbohydrates give a more predictable, stable energy profile than sugar or refined carbohydrates eaten alone, but the effect is variable between people and between studies.

Even mild dehydration — on the order of 1-2% of body weight, a level that's easy to reach without feeling strong thirst, especially in air-conditioned spaces or with low fluid intake during the day — has a documented, negative effect on mood and cognitive function.

The practical takeaway isn't to rigidly stick to "8 glasses a day" — a myth we break down in detail in a separate article — but to drink regularly throughout the day, especially in air-conditioned offices and with higher physical activity, where mild, unnoticed dehydration affecting alertness is easy to develop without a clear feeling of thirst.

Caffeine remains one of the most effective, best-studied alertness aids — but its effectiveness as a daytime energy tool depends strongly on dose, timing, and individual tolerance, not simply on how much coffee you drink.

The two most common mistakes are: taking caffeine immediately upon waking, when natural cortisol levels (and alertness with them) are already elevated, making caffeine's effect less noticeable, and drinking coffee too late in the day, which — as we show in our article on improving sleep quality — can disrupt nighttime sleep even when consumed 6 hours before bed, creating a vicious cycle of worse sleep and greater caffeine need the next day. We cover detailed dosing rules by body weight and time of day in our articles on dosing caffeine by body weight and on when to stop drinking coffee before bed.

A short nap is one of the few interventions on this list with a literal, numerical measurement of performance improvement under conditions close to real-world, professional settings — thanks to classic studies on napping in pilots during long flights.

Outside the aviation context, this principle transfers well to everyday life: a short nap (roughly ten to twenty or thirty minutes), ideally in the early afternoon rather than late afternoon or evening, improves alertness with relatively low risk of interfering with nighttime sleep. Longer naps increase the risk of entering deep sleep and waking up with unpleasant sleep inertia — feeling worse than before the nap. We cover optimal nap timing in more detail in a separate article.

This is the first of three items on this list that's a signal to get a blood test, not a habit to adopt. Iron deficiency is one of the most common, and easily overlooked, causes of chronic fatigue — especially in menstruating women — and this holds even before full-blown anemia visible on a basic complete blood count develops.

Vitamin B12 is essential for red blood cell production and proper nervous system function, and its deficiency — like iron deficiency — is one of the classic, well-documented causes of chronic fatigue in the medical literature, sometimes accompanied by tingling in the extremities or trouble concentrating. We cover this phenomenon in more depth, including one of its lesser-known causes in patients taking metformin, in our article on metformin and vitamin B12 deficiency, and in our knowledge-base entry on vitamin B12.

People on a fully plant-based diet, older adults (due to naturally worse B12 absorption with age), and people taking acid-reducing medications or metformin long-term are at elevated risk and should consider periodic testing of this vitamin's level, rather than assuming chronic fatigue is purely a matter of stress or insufficient sleep.

Hypothyroidism is one of the most common endocrine causes of chronic fatigue, sluggishness and reduced energy — and at the same time one of the easier ones to diagnose, since it only requires a simple blood test (TSH, and if abnormal, thyroid hormone levels as well). We cover this condition in more depth in our entry on hypothyroidism.

The problem is that hypothyroidism symptoms — fatigue, weight gain, feeling cold, slowed thinking — tend to be nonspecific and are easy to attribute to stress, age, or lifestyle, which can delay diagnosis by years. If chronic fatigue accompanies other items on this list (weight gain without a diet change, feeling cold, dry skin, sluggishness), it's worth asking your doctor directly about a TSH test rather than assuming upfront it's "just" a lifestyle issue.

If we had to suggest an order for approaching this list, it would look like this: first sleep, daylight exposure, movement, hydration, and organized meals — because they're free, safe, and act on many mechanisms at once. If, after a few weeks of consistently implementing these habits, energy is still clearly low, the next step shouldn't be another diet change or a new supplement, but a blood test — ferritin, vitamin B12, TSH — because these three deficiencies are surprisingly common and surprisingly often left out of the conversation about "low energy."

Caffeine and napping have their place as short-term tools, but treating them as your main strategy while ignoring sleep, movement, and potential deficiencies is treating the symptom without addressing the cause — a strategy that usually stops working over the long run.