Do my cats know I'm sad??

I have 6 cats, all very different, 2 were born feral so nervous and subtley affectionate the others home bred and very confident, I have 1 unneutered female who the vet won't neuter due to a heart murmur - hence 6 cats! 3 of the 6 cats were home bred, born on my sofa (Mum won't allow the babies to come out unrtil I am with her, won't allow herself or babies to stay in a room unless I am there. When I come home from work all the cats come in, when I go into the garden they all come out with me, they all wait on the steps for me coming home at night, they all come into my bedroom when my alarm goes off. 1 of my cars stands gaurd every night by sitting in my hip, facing the bedroom door. My cats are clearly devoted to me!. All my cats are great with dogs, but my 2 girls will not allow dogs near me??

My daughter is about to move away (north of scotland) and I am desperately upset as I adore my 2 grandchildren (Andrew 2yrs & Megan 2 months) and the distance means I can't be a gran to them or support my daughter who has MS - My heart is breaking.

Recently when I sit down in the evening I find myself covered in cats! 1 cat is 5 years old, long haired and always preferred to sleep outside where it's cooler, he now curls up next to me on the sofa - they even crowd each other!. the ferals have always liked to sleep in quiet corners are sleeping on the back of my chair and the others all fit themselves in around me.It feels as though they want to be really close - is this their way of telling me that they know I am feeling sad and want to offer some comfort?

I think to a degree they do, and mine seem to know when I'm ill as even if it's nice and warm in the house and they have a nest next to the radiator, they will come to bed with me if I'm there during the day.  Of course it might just be that really it's their bed and I keep it nice and warm and provide stroking!

I think that question depends on how much anthropomorphization you associate with your cats. On the completely technical level, cats do have extremely keen senses that can pick up minute differences in your behavior. If you're sad, you move and behave slightly different than normal. If a human can pick up on you being sad by looking at you, it is painfully obvious to a cat. Changes in your breathing, the cadence of your steps, and the rate at which you do normal household activities are all changed when you are sad, and your cats can easily see and hear that.

This is where the anthropomorphizing comes into effect. If you give human attributes to cats, then yes, your cats know you are sad and are doing everything they can to help you out. If you look at it from a purely scientific viewpoint, your cats have noticed you acting strangely and, as a member of their pack, they are confused by this and want to investigate more (hence you being surrounded by cats when you sit down). I'm somewhere in the middle. I know my cats don't detect and understand human emotions the same way we do, but their version achieves the same emotional result to me of making me feel better, regardless of if they are putting reason behind it ("I know this person is sad, so I will cheer them up") or if they are following their base instincts ("The leader of my pack is acting strangely and this unsettles me because I rely heavily on this person. The best thing to do to ensure continued survival is to investigate and fix the issue"). To me, it matters more what I think are the reasons behind my cats' behavior than what their actual thought processes are.

I believe they know how we are feeling whether it be happy, sad, mad, silly... Cats are very sensitive.  They are like mirrors, they take in your cues and they process it and give it back to you.  So if they know you are sad, they certainly will go over to give you a cuddle to help you feel better or just to be supportive.  They know you need it just like they do when they are sad.  Mine certainly do!

Been living with cats all my life and have two of my own now as well. It could just be due to the relationship I have with my cats but I get the distinct impression that

......

they couldnt care less. 

I have never seen anything in my cat's behavior that would indicate that they are aware that I'm ill/ feeling bad. When I recently got my tonsils removed they were jumping on the bed, making noise and trying to make me get up because it was time for their snack. 

I once saw cats described as "the epitomy of indifference", and while that may not accurately describe other cats, I feel like it does describe mine  

Its ok though, its one of the things I like about them.