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Siro Sleep Brief


For this style, we drew inspiration from the boys, and then gave it a little cheek. So soft and comfortable, they’re sure to be a daytime favorite too. Pairs perfectly with the Siro Sleep Bralette or Siro Well-Rounded Bralette, or under any of our bottoms.

  • Full coverage with a little cheekiness
  • Sits at the hip
  • Japanese elastic waistband
  • Good for wild sleepers, hot sleepers and layering
  • Machine wash, cold + lay flat to dry
  • 92% siro micro modal,  8% spandex
  • All underwear are final sale


Runs true to size but for a true boy brief fit, size up.


Christy is featured wearing the White/White and Black/White colorway in size small. She is 5’9” with a 34” bust, a 26” waist, and 36.5” hips.

Jessica is featured wearing the Black colorway in size small. She is 5'7 with a 32" bust, a 25" waist, and 36" hips.

Unsure of your size? No need to lose sleep over it - we are here to help! To ensure proper fit, please refer to the fit guide below and if you have any questions, please feel free to email us at We are happy to guide you!

Size XS S M L XL
Numerical 0 2-4 6-8 10-12 14
Bust 32-33 34-35 36-37 38-39 40-41
Waist 26 27-28 29-30 31-32 33-34
Hip 36 37-38 39-40 41-42 43-44
Inseam 29.5 30 30.5 31 31

Measurements are in inches and refer to body size, not garment dimensions. Please note that fits may vary by style and personal preference.

Need help with your size? Have a suggestion or feedback?

Lunya gladly accepts exchanges and free returns of unworn/unwashed items with the original tags attached within 30 days of your order ship date. Underwear, Gift Cards, & Sale Items are nonrefundable. Please visit our automated ONLINE RETURN PORTAL or email our customer happiness team at to initiate an exchange/return or with any further questions. THX!