Our new material is made with 37.5 technology. 
Watch this demonstration video to see 37.5 technology in action!


What is our new 37.5 material?

37.5 Technology is a dynamic thermoregulation technology that triggers off of humidity.

It helps keep your body at the ideal core temperature of 37.5° Celsius and helps keep the microclimate next to your skin at the ideal relative humidity of 37.5%.

It’s also been proven to increase comfort by removing moisture in the vapor stage, before liquid sweat forms, to delay the onset of sweat.


How does 37.5 material work?

37.5 Technology triggers off of humidity. Humidity is the gauge for whether you are hot or cold. When you’re hot, active particles embedded into the material use your body’s energy to remove moisture and cool you down. When you’re cold, the active particles retain the body’s energy to warm you up.

Patented 37.5 technology uses active particles made from volcanic sand that have billions of micropores, massively increasing the surface area of the material. These particles also absorb infrared (IR) light in the spectrum that the human body emits it, and this light becomes the energy that powers the particle. If no moisture (sweat vapor) is present, meaning you are cool, the particles retain this energy to warm you. If moisture (sweat vapor) is present, meaning you are hot, the particles use this energy to move moisture out of the clothing system. Without these active particles, water has no reason to leave the microclimate until relative humidity is much higher than is comfortable. 37.5 active particles also trap odor molecules and then release them when they’re washed and dried.


Will the technology in 37.5 material ever fade?

The active particles are permanently embedded in the fiber they will last the lifetime of the garment.


What are our sizes?

Goodnighties are true-to-size, non- binding made with a comfy 4-way stretch. 

Size Charts







Can I buy a top and pants in a different size or color?

Yes, because we are 100% Made in the USA we are able to accommodate mix & match tops, shorts, pants, sizing, styles and colors - so be creative! All  Items are sold separately! No problem if you need a medium top and a large bottom.


What is the best way to wash and care for Goodnighties?

Machine wash cold with like colors. Only non-chlorine bleach when needed. Do not use softeners. Tumble dry low. Iron if needed on low. Do not dry clean.


What are our new colors?

  • Midnight
  • Deep Sea
  • Seafoam
  • Lavender Breeze
  • Pink Paradise
  • Heartthrob
  • Glacier Blue
  • Wine
  • Moonstone
  • Candlelight


How will I know that my order is on its way?

After registering you will receive a confirmation email. You will then get an email when your item shipped with tracking.  If you place an order with us and don’t get a confirmation email check your “junk” or “spam” mail folder as it may be there. 


How long does it take on average to receive my order once shipped? 

Most of our orders are shipped within 1-2 weeks or less.

Our normal shipping is through USPS priority mail (with tracking) in the USA, We ship internationally using UPS! Shipping charges for International is a flat rate of $25.


Questions on your order? Contact us at




If you are not satisfied with your sleepwear products for any reason you may return or exchange your item within 30 days. Product must be returned to us in its original condition with original packaging complete with tags within 30 days of purchase.  Return requests must be approved prior to shipping it back.  Please contact to request a return and receive instructions for how to proceed, or call our customer service team at 570-793-2108.

Return shipping fees are paid by the customer. If it is our mistake and we've sent you the wrong product or size, we will pick up the package at our expense and exchange for the correct size or product.

For exchanges, if there is a cost difference between your returned item and the replacement item, we will provide a credit; however, if the replacement item is higher in price, we will contact you for approval of any additional charges. Promotional discounts do not apply to exchange requests. Please allow 2 weeks for returns processing.  There is no cost to exchange your product for the same style item except for the postage you pay to return the item. Any shipping fees originally paid on your order are non-refundable. If credit is issued, it will be issued to the credit card used on your original purchase. Good Nighties is not responsible for incorrect order information submitted at the time of purchase. Any packages returned as "non-deliverable, Return to Sender or Refused" will be charged a restocking fee.

We don't often have product defects, but if you discover a defect on any of our products, please send an image of the product defect to our customer service team at and we will do our best to remedy the problem.


We are dedicated to providing you, our customers, with high quality products. We guarantee that the materials and workmanship used for each of our products will be of excellent quality and that they will serve to the satisfaction of our customers.