Every day after lunch something strange happens to me. In the morning I can listen to my teachers and finish my work, but at around two o’clock my eyes become heavy and even a simple paragraph feels too long. Last Thursday it became worse. I had eaten lunch, but my water bottle was still almost full because I forgot to drink from it.
During English class, I read the same question three times and still did not understand it. My friend said I was having an “energy crash.” I thought maybe lunch had made me sleepy, but our teacher asked if I had drunk enough water. That made me curious about hydration and energy crashes, because I never thought my water bottle could be connected to my afternoon sleepiness.
What is an energy crash anyway?
An energy crash is not like a real crash with broken things. It is just the name people use when they suddenly feel tired, sleepy, slow or unable to concentrate.
For me it feels like somebody has turned the brightness of my brain down. I can still do my work, but everything takes more effort. I become irritated very easily too. Even the sound of someone clicking a pen starts bothering me, which is not really the pen’s fault.
When I searched “afternoon fatigue causes,” I found that water is only one possible reason. Poor sleep, stress, heat, illness, hunger and the food we eat can also change how energetic we feel. So an afternoon crash cannot be blamed on dehydration every time.
Our body already has an afternoon dip
My teacher explained something I did not know before. Our body follows a 24-hour clock called the circadian rhythm. This clock helps control when we feel awake and when we feel sleepy.
The National Institute of General Medical Sciences says typical circadian rhythms can produce high energy from around 10 a.m. to 1 p.m., followed by an afternoon slump. So feeling a little sleepy after lunch does not always mean something is wrong.
A review called “The Post-Lunch Dip in Performance” also explained that performance can dip during the middle of the afternoon because people naturally become more ready for sleep at that time.
I found this funny because we call it the post-lunch dip, but lunch is not the only reason. The body clock was doing some of it anyway. Lunch just happens to sit there and get all the blame.
Then where does water come into it?
Water does not provide energy like food does. It has no calories, so a glass of water cannot work like a magic battery. But the body still need enough fluid to do its normal jobs, such as controlling temperature, moving nutrients and getting rid of waste.
If someone has not drank enough, they may feel thirsty, tired, dizzy or uncomfortable. The Mayo Clinic lists tiredness, dizziness, dark urine and confusion among possible signs of dehydration.
That is where dehydration tiredness can become part of an afternoon crash. The person may already have the normal sleepy feeling from their body clock, and being low on fluid may add one more uncomfortable thing on top of it.
This does not mean every tired child just needs water. Sometimes a person needs sleep, food, shade or a doctor, not another bottle.
What one water study found
I wanted to know if drinking more water can really change how energetic people feel, so I found a 2014 study published in PLOS ONE. It included 52 adults with different water-drinking habits.
There were 22 people who normally drank between 2 and 4 litres of water each day. Researchers asked them to reduce their water intake to 1 litre a day. Another 30 people who normally drank less than 1.2 litres were asked to increase it to 2.5 litres.
The study found that the low-water group reported less fatigue, confusion and thirst after increasing their water intake. The people who reduced their usual intake reported more thirst and less calmness, positive emotion and energy. You can read the study on PubMed.
At first this sounded like a final answer to me. More water means more energy. But then I noticed the changed drinking period was only three days. The study was also funded by Danone Research, and some researchers worked for or consulted with the company. That does not automatically make the research wrong, but it is important to know.
Also, it was about adults and their reported feelings. It did not prove that water will fix every child’s afternoon crash.
I tried a small experiment on myself
I decided to pay attention for one school week. This was not a real scientific experiment because it only had one child in it, and that child was me.
On Monday I forgot to drink most of my water and felt sleepy after lunch. On Tuesday I drank more regularly and felt better. But on Wednesday I drank water and still felt tired because I had stayed awake late finishing a drawing and then watching one extra cartoon.
So my results was completely mixed.
I searched “hydration for energy levels” and many pages made it sound very simple. But my week showed me that water is only one piece. It may help when low fluid is contributing to tiredness, but it cannot undo a late night or make a boring chapter suddenly exciting.
Can one glass beat the afternoon slump?
One day my friend saw me drinking water before class and asked if I was trying to “charge” myself. I told him maybe a little, but not in the way he meant.
The phrase “beat afternoon slump water” came up when I searched online, and it sounded like water was fighting the afternoon in a boxing match. Drinking enough may help us avoid dehydration, but it cannot completely remove the natural afternoon dip.
Taking a short movement break, getting some daylight, sleeping properly and eating a balanced lunch may also matter. Our teacher sometimes makes us stand and stretch for two minutes, and honestly that wakes me up more faster than staring at my notebook.
Small habits that helped me
I stopped trying to finish my entire bottle only when I became very thirsty. Now I take a few sips after assembly, before lunch and after games. It is easier because I do not have to remember a huge amount at once.
I also look at my urine colour. Darker urine can sometimes be a sign that the body needs more fluid, although medicines, food and health conditions can also change it. There is no one perfect amount of water for everybody because weather, activity, age and health are different.
People with heart, kidney or other medical conditions may receive special fluid advice. They should follow their doctor instead of copying someone else’s bottle target.
Severe confusion, fainting, very little urine, unusual sleepiness, rapid breathing or a fast heartbeat need help from an adult and medical professional. MedlinePlus lists these among signs that dehydration may be serious.
What I understand now
Hydration and energy crashes are connected, but water is not the full answer. Being low on fluid can add tiredness and discomfort to the normal afternoon dip. But sleep, lunch, heat, stress and our body clock also decide how we feel.
I still become sleepy during afternoon class sometimes. Yesterday my bottle was full, I had slept properly and I still yawned during grammar. Maybe grammar has its own special power.
But now I drink small amounts throughout the day instead of waiting until my mouth feels dry. The water I take is more alkaline and more hydrated. It does not turn me into an energetic superhero. It just removes one small reason for feeling tired, and I think that is useful enough.
Sources
- Average Teen Circadian Cycle — National Institute of General Medical Sciences
- The Post-Lunch Dip in Performance — PubMed
- Effects of Changes in Water Intake on Mood — PubMed
- Dehydration — MedlinePlus
Author bio: This guest article was put together with editorial help from the team at Dvine H2O, a company that works on clean, everyday drinking water for Indian homes. You can read more about their work on the [Dvine H2O homepage link].
