Energy drinks can prop you up now, but the combo of high caffeine + other stimulants + sugar can cost you tomorrow by disrupting sleep and nudging up heart strain.
What’s actually in the can?
Energy drinks can prop you up now, but the mix of high caffeine, added stimulants and sugar can cost you later by disturbing sleep and nudging up heart load. In trials, standard energy drinks (not caffeine alone) have raised blood pressure and prolonged the heart’s QTc interval more than matched caffeine, which suggests the full formulation matters, not just the caffeine dose. [1]
Tonight’s trade-off: alert now, worse sleep later
Sleep is one of your biggest recovery tools. Reviews consistently link shorter or poorer sleep with worse next-day outcomes in athletes - higher perceived effort, reduced sprint ability and shakier decision-making. Late-day stimulants make that more likely. If training or competing tomorrow matters, be cautious with evening cans. [3,4]
Heart load: small numbers that add up
Randomised crossover trials report energy drinks can produce measurable rises in systolic BP and prolong QTc for several hours; caffeine-only comparators didn’t explain the whole effect. If you already feel “wired” after hard sessions, layering an energy drink on top can keep HR and BP elevated into the night which is not ideal for recovery. [1,5]
Sugar and “extras.”
Many cans carry 25–55 g of sugar per serving, pushing up total free-sugar intake. UK guidance advises keeping free sugars to ≤30 g/day for adults. [6] Even “zero” versions still stack caffeine and other actives (like guarana) that can add extra, undeclared caffeine. [2]
A smarter alternative
KURE Oxygen Water - A portable and affordable oxygen supplement that fuels hydration and recovery whenever you need it.
Sourced from Cornish spring water and enhanced with up to 10× more oxygen than standard bottled water, KURE offers a clean, daily supplement designed to support active lifestyles, recovery and everyday wellness.
The bottom line
Energy drinks can sharpen you today, but the price is often tonight’s sleep and tomorrow’s legs; if tomorrow matters, keep caffeine earlier, protect sleep and reach for gentler options in the evening such as electrolytes, chocolate milk or KURE Oxygen Water.
References
[1] Randomized Controlled Trial of High-Volume Energy Drink Versus Caffeine Consumption on ECG and Hemodynamic Parameters
[2] German Federal Institute for Risk Assessment (BfR). Health risks associated with high caffeine intakes and energy drinks.
[3] Sleep and athletic performance.
[4] Sleep and athletic performance: the effects of sleep loss on exercise performance, and physiological and cognitive responses to exercise
[5] Effects of energy drinks on the cardiovascular system
[6] NHS — Free sugars: recommendation ≤30 g/day for adults.
