Dilemma

I have spent the last few days up a ladder with a paint brush in my hand, so much time in fact that when I got into bed last night, every time I closed my eyes I felt like I was falling from a ladder. After working all day on the house I have been spending all evening working on my thesis and last night spent half the night on it as well. The result is that today I'm tired and could quite easily go to sleep now, in the middle of the day. The problem I've got is do have a nap now and see if it makes working later easier or plod on and crash early tonight? If I sleep in the day I tend to wake feeling groggy but my bed looks so inviting!