keeping strong visual and spatial skills, recognizing shapes
planning and organizing
These are the common symptoms of brain fog. And there are a few reasons why it happens to the best of us.
What are the causes of brain fog?
There are several causes of brain fog. And when I say several, I mean a long list of reasons why it happens to most of us. Are you ready for a scroll marathon?
Here are 8 causes of brain fog:
Lack of sleep
Sleep rejuvenates the brain and prepares it for the next day. According to Scientific American, “Sleep serves to reenergize the body's cells, clear waste from the brain, and support learning and memory.” 
Not having enough sleep can hinder brain functions and may lead to poor focus, concentration and other cognitive functions.
Having trouble sleeping? Then here are a few articles that can give you life hacks and some better-quality snooze:
Sleep apnea is a “potentially serious disorder in which breathing repeatedly stops and starts.” 
A pretty good indication that you have this is when somebody has told you that you snore loudly, and you feel unbelievably exhausted even when you’ve had a full 8-hour sleep.
This just means that you had trouble breathing throughout the night.
Sleep apnea gets in the way of having good quality sleep. It eventually keeps your brain from going through the process of renewing and restoring cells.
Vitamin B-12 is important in maintaining healthy brain function. On the flip side, vitamin deficiency can cause brain fog.
If you want to steer clear of mental fatigue, then be more mindful of what you eat. A great start is removing too much MSG, aspartame, peanuts and dairy from your diet. 
Stress causes several negative effects on our body.  These include heightened blood pressure, hair loss, weak immune system, depression, and yes, brain fog. When we’re stressed, cortisol levels are high, making it hard to concentrate, think rationally, and reason.
A change in levels of progesterone and estrogen during pregnancy and menopause sets off brain fog. Hormonal changes – and sometimes imbalance – like this can result in poor memory and lack of mental clarity, and poor concentration, albeit in the short-term.
A 2013 study showed that women transitioning to menopause suffered from hormonal changes, and eventually, forgetfulness and trouble focusing on challenging tasks. 
Another indication of effects of hormonal imbalance on brain fog is its presence in thyroid disorders. People suffering from hypothyroidism and Hashimoto’s disease also experience difficulty remembering and solving complex problems. 
Depression and anxiety
Imagine a moment when you’re going through high emotions. Was it easy to focus at the time?
It’s really no easy feat to think, concentrate and process information when there’s lack of motivation or a high level of anxiety. Depression and anxiety are both serious mood disorders that alter our brain’s cognitive functions, especially memory, focus, rational-thinking and decision-making.
Brain fog is a common side effect of certain medications and treatments. This is more common in cancer treatments, and is sometimes known as chemo brain.
When this happens, consult your doctor and check if you could switch to a lower dose or another one that will prevent brain fog.
Other medical conditions
Certain medical conditions can also cause brain fog, most of them are linked to fatigue, variations in blood glucose level and inflammation. Some of these medical conditions are: 
Chronic fatigue syndrome
Caffeine stimulates concentration and mental performance.
Within 15 minutes of consuming caffeine, you’ll already feel its stimulating effects. One of them is being more alert, attentive and laser-focused.
Livestrong cites a 2009 study from “Cognitive Science” which validates that caffeine “can improve your mental faculties and alleviate fatigue.” 
The same article, however, warns about going overboard with caffeine. Having one too many cups of joe in a day can be counter-productive, and can cause brain fog:
As you go up with a caffeine boost, so you must come down. If you are prone to ingesting high amounts of caffeine, more than 500 mg a day, brain fog can set in. Insomnia, irritability, poor concentration, anxiety and restlessness are a few of the consequences of heavy caffeine use. These effects can occur hours after your last dose and may prompt you to consume more caffeine to counter the effects. However, the cause is not the cure in this case, and you may want to consider weening yourself off of high-dose use.
Erectile dysfunction. In combination, those are two of the ugliest words known to man. But can caffeine help you get it up?
Science hasn't found the definitive answer to this question, but one study concluded that fewer men who consume caffeine have problems performing. The study said:
Caffeine intake reduced the odds of prevalent ED, especially an intake equivalent to approximately 2-3 daily cups of coffee (170-375 mg/day). This reduction was also observed among overweight/obese and hypertensive, but not among diabetic men. Yet, these associations are warranted to be investigated in prospective studies