I get like that sometimes. I just feel so sleepy and have to go back to bed. For me, it's mostly when my allergies are acting up or I'm sick. It is different from the MS related fatigue though. For me, MS related fatigue is overwhelming and at times I feel as if something toxic is in my body. My body gets so heavy and tired. This is a horrible feeling and one that I get often with the MS, especially if I don't nap during the day.
Also, sometimes our quality of sleep can leave us feeling that way. If I have a rough night, I am sure to feel that way in the morning.
You may be coming down with something too or it may be something else not related to your MS, especially if this is not your normal fatigue. Keep track of it and if it continues, talk to your dr. about it.
I hope you start to feel better soon.