Did a little research:
See Halichot bat Yisrael, p. 230 and fn. 241 (Hebrew
edition)
Rabbi Ari Enkin (from AishDas)
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There is some discussion in halachic literature of a custom for women not to perform certain labors on Motzaei Shabbat, such as sewing and
knitting.[1] The origin of this custom is related to the legend that when Mashiach comes there will no longer be a need to sew clothes. As there is an increased potential for Mashiach to arrive on a Motzaei Shabbat, the custom of refraining from sewing on Motzaei Shabbat evolved accordingly.
Other authorities argue there is no such custom for women not to do certain forms of work on motzaei Shabbat, at least not one which is based in any classical sources, and women are free to dismiss the custom should they so desire.[2]
Closely related to the custom of not sewing on motzaei Shabbat is the
tradition that when the Jewish people left Egypt they brought no sewing or clothing manufacturing utensils with them.[3] Instead, the clothes they were wearing upon their departure from Egypt miraculously remianed fresh and clean and even grew with them as their clothing sizes changed.[4] Indeed, included in this Divine tailoring service was deodorant and
anti-perspirant for all the hot days in the desert. As such, in a gesture of longing and awaiting future days, the ladies of certain communities accepted upon themselves to refrain from sewing and similar activities at the conclusion of Shabbat. Indeed, Motzaei Shabbat is a popular time for a number of rituals, prayers, and spiritual practices related to the coming of Mashiach.
[1] Magen Avraham O.C. 299
[2] Rivevot Ephraim 2:107
[3] Shir Hashirim Rabba 4
[4] Ibn Ezra; Devarim 8
Rabbi Ari Enkin Ramat Beit Shemesh, Israel Cell: 011 972 52 579 1773 / Res: 011 972 2 992 0241
There it says original Abuduram (a rishon I believe). Mishnah Berurah does not discuss (meaning doesn’t bring down minhag l’halacha). It also brings the Aruch HaShulchan:
??? ?? ???? ????? ????? ??? ????? ????? ?? ????? ?? ????? ??? (??”? ???”?), ?????? ?? ????? ????? ??? ???? ???? ????????, ???? ???? ?? ?? ??? ????? ??? ?????, ???? ?? ????? ?? ??????? ??? ????.
Translation:
There are those women who are accustomed not to do work all night of Motzei Shabbos (M’A), we did not hear of such things and it is against the Talmud Yerushalmi, our Women (ie one’s of his day) only don’t do work until after Havdalah, but afterwards do all melachas, so is the law.
So you have Rav Ephraim Greenblatt zatzal (mentioned above) and Aruch HaShulchan. Probably should ask a Rabbi, but if it is for relaxing – I imagine you have what to rely on.
DQB