Sleep Short - Super Heavy Flow
Sleep short boxer style period underwear
Close up Grey sleep short boxer style period pants with stitching detail
Sleep Short - Super Heavy Flow
Sleep Short - Super Heavy Flow

Sleep Short - Super Heavy Flow

Regular price £32.95
Tax included. Shipping calculated at checkout.

These comfy Sleep Short style period undies are built with super absorbency to keep you protected all night long. With a protective layer offering extra coverage from front to back, you can rest assured you'll be protected from stained sheets and midnight leaks!

Our super-heavy Sleep Shorts hold up to 5 tampons worth (that's our most absorbent yet!)

  • Classic, comfortable cotton
  • Holds 5 tampons' worth or 25-30ml
  • Wear all night on super heavy flow
  • For periods, leaks & incontinence
  • Protection layer from front to back
  • OEKO-Tex certified materials

🍃 Bleed Green: Each pair of period pants replace 200+ disposables from going to landfill, reducing your waste by 99.5%

🤝 Giving Back: For every purchase, we give back to a girl in need. Find out more about our #ByYouForHer giving back scheme here

We offer free shipping on all UK orders and free shipping on International orders over £75.
For same-day dispatch and next day delivery, please place your order before 1pm.
All orders are dispatched from our UK warehouse using trusted couriers such as Royal Mail, DHL and DPD. 
Think our period pants sound too good to be true? Take them on a risk-free trial for 60 days!

If our undies don't work as promised, let us know within 60 days and we'll refund you, no questions asked. The 60-day risk free trial applies to one worn pair of undies only. Refunds will be paid to the original payment method that was used to place the order.
🚿 Rinse after use.
🧽 Machine wash on 30-40 degrees.
 🍃 Hang to dry or dry indoors on a radiator.
⚠️ Do not use fabric softener or bleach. No tumble drying.
And that's it! Your FLUX Undies are ready to wear again!

Our Period Pants Are:

Sustainably Manufactured

We only use eco-friendly materials that are sustainably manufactured

Vegan and Cruelty-Free

Made from natural materials and never with animal materials or testing

Free From Nasties

Certified safe for skin and free from toxins, chemicals and fragrances.

60-Day Money Back Guarantee
How They Work

Our period pants absorb up to 5 tampons' worth of liquid, yet they look and feel just like regular undies.

Our built-in tech works like this:

1. Top layer wicks moisture away from the surface quickly, to keep you dry

2. Our middle layers absorb your blood and lock in your flow

3. The bottom layer pushes liquid back up and keeps you leak-free

It's simple. Just wear, wash and reuse.

Blood, Sweat, Whatever.

Three layers of fabric absorbing liquid showing how period pants work

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Customer Reviews

Based on 32 reviews
Shai Brown (Peterborough, GB)
Flow: Heavy
Products used: FLUX Undies, obvs!, Tampons, Disposable pads
Almost perfect

These are super absorbent and I’ve had no issues with leaking at all, my only problem is that they are a bit tighter than I would have liked so I would recommend sizing up.

K. B. (Albuquerque, US)
Flow: Super Heavy, Heavy, Moderate
Products used: FLUX Undies, obvs!
Most comfortable period product ever

After having my child, tampons became incredibly uncomfortable for me, and they’d always been kind of annoying so I switched to pads. Those were ok for a while, definitely convenient, but I started to develop a sensitivity to the adhesive backing. Trust me, having hives around your crotch and on the exact areas your thighs rub together is awful.
I found out about period panties, and I bought a couple pairs to try out. That was a few months ago, and since then I’ve bought another ten pairs from Flux! They’re not bulky (which I was concerned about). They feel just like regular panties, just a little thicker, and they’re surprisingly easy to keep clean. They’re not as convenient as a pad or tampon you can just toss after it’s used, of course, but if you have two or three pairs it’s very simple to get a rotation going. I was also worried at first about smell, but the panties don’t smell any more than a disposable pad does. And once you wash them the smell goes away. I don’t get rashes anymore, I haven’t leaked on my sheets or clothing once, I’m not contributing to the massive amounts of trash created by disposable period products. It just feels good all around.

Sorry for the extended essay, I’ll sum up: I’ll never go back to disposable pads and tampons.

Sarah (Minehead, GB)
Flow: Super Heavy, Heavy
Products used: FLUX Undies, obvs!, Disposable pads
Great comfortable fit no more blood stained bed sheets.

Definitely love the secure feeling these pants give. They are great for heavy flow over night. I have heavy periods for 4-5 days so would need to get several pairs to wash and dry for each day. They do take a while to dry and can smell musty if stored when not totally dry after washing.
They were dried all day on the washing line on a warm summers day but still damp after 8 hours.
I think they might be tricky to dry in colder months.

Cecília Ligero (Sant Lluis, ES)
Flow: Super Heavy, Heavy, Moderate
Products used: FLUX Undies, obvs!, Menstrual cup

I tried it once, and automatically bought the second ones.
Nowadays I don't know what was I doing before having these sleep shorts.
I prefer them for sleep but I've also used them wearing a dress. So comfortable!
You can be calm while wearing them, carefree.

Customer (Swanley, GB)

I absolutely love the sleep shorts! I have a heavy flow and feel particularly uncomfortable at night often waking up a few times worried if I have leaked... but not with these sleep shorts they are the perfect fit and hug your body to ensure no leaks. I am a 10/12 and bought size 12 they are nice and fitted so if you’re inbetween sizes I’d say go for the bigger size. Also very soft & comfy - oh and they are reusable so you’re helping the planet! If you’re thinking of buying then do it! 😊

Lucy Jane Wallace (Hartlepool, GB)
Flow: Super Heavy, Heavy, Moderate
Products used: FLUX Undies, obvs!, Tampons

I can’t recommend these undies enough!! I used them yesterday for the first time and all I can say is WOW!! I’ve just added another two pair (different styles) to my basket before writing this review! Literally changed my period for the better!