Current me scoffs at 5 hours of sleep as well.  Not anywhere near enough sleep.

5 hours of sleep seems a bit light.  If you want to avoid the Con Crud best to think more about 7 -8 hours.

Also, please shower, wear deodorant and wash your hands after going to restroom!

Yeah what is with people not washing their hands? It's gross.

As for sleep, many years of working multiple jobs has conditioned me to get by on less sleep."Younger me's" record was four days of being awake, not for gaming, it might have been an unfortunate amount of work schedule shuffling with multiple jobs, but I no longer remember. I just never went to bed and didn't even really feel tired but by the end of the fourth day I was watching a garbage can melt. It was a "unique" experience. At any rate I am certainly no longer capable of such feats, and don't really recommend them to others.

2013 GenCon I averaged 9 miles per day -- shuttled from airport hotels.  2015 GenCon I averaged 11 miles per day, DownTown hotel.

If you are a RPGr or Magic person and generally just sit most con, you probably can skip your normally skipped meals. If you are me, on the other hand...

• Pack 2 pairs of trustworthy, not too old, but not new-new shoes.
  
• Full clothing change out is essential half way through day. Shower if Downtown, use wipes in rest room if commuting.  Dry shampoo for your hair is handy-dandy too.
  
• Eat when you're hungry. Pack sealed snacks to save money and time. More protein and fat, less sugar.  It's fine to graze from your backpack for breakfast and lunch and have a fulfilling dinner with something fresh and green. 
  

Everyone's individual needs vary wildly. Sticking to a strict number thing is kind of arbitrary. 

For instance, 3 meals a day? 2 showers? 5 hours of sleep? 

Some people are fine with 4 hours of sleep and coffee some nights, and more sleep other nights. Some people are fine eating twice a day and snacking. I personally eat one meal a day and then small snacks most of the day.

The 2 showers is just weird to me. How sweaty are you? I can shower before bed and I am fine the following day, typically. I rarely stand outside in the heat and find that as long as proper antiperspirant deodorant is utilized, you're fine. For larger individuals that don't wear deodorant, I have smelled them pretty far away, but I suspect they aren't showering even once a day at that.

I'm also seeing people start to peddle around the "drink water, wear good shoes, eat food if you are hungry" over and over. These lists are starting to become more like explaining to kids what to do as parents, instead of actual advice. It's a air conditioned building where you'll walk a few miles. Not war.

I suspect soon these lists will include breathing at proper times for good oxygen regulation, too.

If your "con crud" is picking up within 24 hours of the convention ending, odds are very strong you already had it, and the exhaustion exacerbated it.  Incubation periods being a thing and all.

Six hours sleep for me is about right, and man I always have to shower in the morning just to wake up!  Not to mention my hair feels greasy and I just feel plain icky throughout the day if I don't get that a.m. shower.

4 events per day depends on the length of the events you are playing.  I generally play 4 hour RPGs.  Four of those a day would be a brutal 16 hour marathon, especially if they were back to back.  I do 2-3, one usually a seminar or something shorter.  Then spend some time in the dealer area (usually in the morning).  That's plenty and allows for meals.

Yeah I disagree with most of these.

5 hours sleep?  Should be 7.  I agree with others, this is the #1 way to avoid the con crud.  No sleep = weak immune system = sickness.
4 scheduled events?  I do as many as I can fit, leaving some time for dealers and meals.
3 meals?  I usually skip breakfast in real life so 2 is fine.  Hydration is super important though.
2 showers?  Most people don't have connected hotels to be able to do this.  1 shower though, absolutely.
1 trip through exhibit?  Ok, agreed.

Yeah I will definitely be showering twice. At wake up and before bed. But I normally do that already so not a big deal. 

https://www.theguardian.com/science/2016/jan/24/health-foods-immune-system-colds-vitamins

"Why binging on health foods won't boost your immune system"

(Yes, I know what I said...:))

Nah, the Mayo Clinic website says cold symptoms appear 1 to 3 days after infection. If you have a cold right after the Con, it had something to do with those 60,000 people you gamed with.