Two 5 month old kittens suddenly lethargic

Hi, 

I recently adopted two gorgeous tabby cats. They are usually full of energy and want to play (especially the male). 

Yesterday I noticed that neither one of them wanted to chase the laser, play, run around, etc. All they have done is sleep for the past 36 hours or so. 

They are both eating and drinking normally, in fact their appetites are great. 

But I am really concerned, because they just don't seem like themselves. I took their temperatures, and they are also normal. 

Any ideas? I plan to call the vet tomorrow, but I am freaking out tonight. 

Thanks!

As long as they are eating, drinking, and using the litter box I don't think this is an emergency.  They should be okay until you call tomorrow.

Thank you Denise. I've been googling (always a bad idea!), and read a lot of horror stories about lethargic cats ending up having FIP or other awful things. It's so hard not to worry. 

Since they are eating and using the box normally, I'd say it's a growth spurt coming on.  My guy would be like that just before a growth spurt.  Kittens grow in their sleep, which is weird to me, but makes sense that they would need a lot of sleep prior to a spurt.

Thanks so much. I thought about that yesterday, and it was a bright spot. They are slightly more alert today, but still very sleepy. It's odd that they are not running around and playing, and that it's both of them at the same time. 

Keep an eye on them.  If they continue to be lethargic, call the vet.  If you notice any change in eating or litter box habits, that's cause for concern as well.  As long as they are eating, drinking, and using the box normally I would think they're okay.  Do you have an ear thermometer you can use to check their temperature?  Do you know how to test for dehydration?  Just pinch the skin on the neck.  If it stands up like a teepee, then they are dehydrated.  If it snaps back down, then they're fine.