For the uses you're describing I use two different tops. For moving I like an un-insulated soft shell over the base layer. Not as much loft or insulation as a fleece but more wind-resistant and still breathable and quiet. For sleeping I like a soft thin hoodie, I have a couple, one by NW Alpine and one Kuiu IIRC. They're what I'd call a lightwieght mid layer, waffle-weave and heavier than a base layer but not as thick as a mid. Much more comfortable to sleep in IMO than most mids you'd wear. Worn under the soft shell the combo is as warm as a heavier mid-layer, and worn without the soft shell it's about as light a mid-layer as you can get.
