Welcome to the beginning of ‘casual attire’, the category Jean-Luc has the most autonomy over. I start with his various pajamas and robes.
Jean-Luc loves a wrap top and the resulting v-neck. It’s his number one recurring choice.
In very general terms a v-neck is considered more casual than a crew neck – and that makes it more bourgeois. This is a t-shirt worn to relax, not to work. They are also more typical to European fashion than American. Both these points fit Jean-Luc, who grew up on a vineyard in France.
Jean-Luc is also clearly comfortable with his body, at least when relaxed. He not only consistently shows off his chest, he sleeps in (cute tailored) shorts, and his body language says he’s at ease, even when he unexpectedly find himself standing in his flirty Frenchman pjs in the middle of a lab.
These blue pajamas (seen under the robe below, too) are likely all the same, or at least the same type.
And these are also likely the same, with the rosy color evident in the second cap merely a trick of the light – there is certainly a pink hue over everything (because they’re in Deanna’s quarters and, as established during her Fashion Project, pink is her favourite colour).
In any case, Jean-Luc knows what he likes to relax in.
He wears a version of pajamas in one other instance, in which he is notably not relaxed.
Here he is imprisoned and being tortured – and his body, while exhausted, remains tense.