I think a lot of adults don't read YA and teens too, for that matter, don't read YA because they believe it is a lighter read. I read a lot of of YA and I typically don't read what I call the bubble gum variety. I prefer my YA to mirror my adult reading at its core. I look for depth, quality writing, complex issues and definitive style or voice. I don't find books that make me think or question not relaxing. Typically if everything sits on the surface, I'm disappointed if not annoyed.

How many readers here specifically read YA because they want something light? Do you only read light or it depends on your mood or the writer? And how do you define light?

I read YA books that I think will be good, quality literature.  I don't read it because I'm looking for something with no sex, with bad writing (some people have dismissed all YA as having bad writing, but not usually in this forum), with no bad language, and with little substance.  I'm disappointed when I read a book with no substance when I was expecting more.

I sometimes do look for light reads, but I don't exclusively look to the YA set to find them.

I don't think it's lighter. I also don't seek out books just because they are 'light.' There is a lot of 'heavy' YA out there.

I tend to really enjoy a lot of the YA subject matter...  some are lighter, but others, are really very deep...  intense reads...  I think I just enjoy the styles of writing and subject matter....  I feel there is quite a lot of variety..... 

I'm usually more of a fan of the "bubble gum" variety actually.  This is for both YA and Adult fiction.  I think YA is just like Adult fiction, in that you can find light topics and deep topics.  Depending on your mood, there are tons of choices available.

I like the absence of sex and language and the lack of extra flowery words. I want to get to the meat of the story and YA seems to condense the stories.

This is exactly why I go to YA. I'll usually pick up a YA book after reading a few more serious books in a row, just to get into something different every once in a while.

i don't know about absence of sex and language in YA. i've read lots of YA books that have both. maybe not to the extent of erotica but characters in YA are definately having sex and cursing

I like that sex/violence is less graphically described in YA books. I'm fine with characters having sex or violence occuring if it contributes to the story, but I feel the level of detail in the description of sex/violence in many adult books is excessive and is not contributing anything to the story for me at that point. If the characters having sex advances the story fine - but I don't need to read a 10 page description of the act!

The YA I read is not lighter. If I want lighter fare, I intentionally seek out chick lit or something similar, but I read YA because I can find amazing stories and plot and characters and I like in a somewhat condensed setting. 

I feel like with adult fiction it's harder to wade through the author's "artistic" style to get to the heart of the matter. I read for substance, not style.

I think that YA used to be the lighter stuff without sex.  But now the marketing has changed.   A number of books I see in the YA reprints are SFF that was marketed to adults and is now being reissued as YA. 

(Such as Pat Murphy and Jane Lindskold.  Their books were both released as adult SF, and are being reissued as trade sized YA.)