Black Friday may be the most significant sales day of the year, but there's a darker side of which most people may not be aware.

Black Friday 2015 is upon us, which means millions of shoppers will take advantage of deals from retailers like Walmart, Target, Best Buy, Macy's, Barnes & Noble and many more. For those who brave the cold early on Friday, Black Friday is an essential tradition. And those who don't go shopping on this day tend to mock those who do.

But this holiday tradition isn't as innocent and frivolous as some may think. Retailers tend to manipulate sales in shady ways, some stores save their best sales for other days and many customers have actually lost their lives.

So, here are five dark facts you may not know about Black Friday:

Derivative products everywhere
 

Those flashy doorbuster sales on products like Smart TVs aren't always what they seem. Companies have been known to create "derivative products" that may look and seem like those regularly sold but are actually made with cheaper parts and have slight differences. A Time report wrote about companies like Sony and Samsung making derivative TVs in recent years. Check the model number of what you're buying and research if other stores are carrying it in order to scope out derivative products.

Most traffic is actually in the afternoon
 

The news creates a perception that stores get a majority of their traffic in the early morning hours of Black Friday, which could scare people away. But the afternoon (between 2-4 p.m.) is the most frequent time period for shoppers on Black Friday. You don't have to wake up at the crack of dawn, but shopping in the morning will probably be less stressful than if you do it in the afternoon.

Mail rebate trick

While retailers may boast of big deals, some of them make customers send in a mail rebate in order to get their discount. But they tend to advertise this mail rebate deal in small lettering, and many customers either don't know of the rebate or aren't motivated to mail it. So in a sense, you're going through the hassle of Black Friday and not getting a real bang for your buck. Check sales carefully for this trick.

You may not even find the best deals on Black Friday

Black Friday has traditionally become known as the day of discounts and sales, but this isn't always the case. In the week leading up to Christmas, some retailers sell their products for 10-15 percent less than they do on Black Friday. So even if you think you're getting a good deal on Black Friday, you may get a better one if you procrastinate on shopping.

You're risking your life
 

Perhaps the most significant dark fact about Black Friday is the amount of death it has caused over the years. There is even a website called blackfridaydeathcount.com keeping track of the amount of deaths and injuries incurred either on Black Friday or as a result of it. There have been seven recorded deaths since 2006 and 98 injuries. With crowds storming store entrances and the overall mad dash to snatch products, take extra precaution on Friday.

Tags: black friday Black Friday 2015