From the original modpage:

Your hair has been in a style suitable for the stressful world of the Dragonborn, but now it's time to relax. Let you hair down, relieve the stress, and enjoy a mead or two.

Let Your Hair Down allows you to set an 'Up' and "Down' hair style (via the MCM) that automatically switches depending on the location you're in. Simply select your hairstyles via RaceMenu, assign the hair styles in the MCM, and that's it! Your hair will toggle down when you are in homes, inns, castles etc., and the rest of the time you will assume your normal combat hair style.

Locations:
Supported Interior Location Keywords Include:
- PlayerHouse
- House
- Dwelling
- Steward's Dwelling
- Inn
- Store
- Temple
- Cities & Towns (Optional in MCM). Will toggle as soon as you enter a city or town (usually exterior) location.

Saving:
Save your preferences and up to 5 hair combos.

Q&A + Known Issues:
- See the bottom of this page

ANIMATIONS:
Due to a lot of community suggestions, I've added some animations to putting your hair up and down. There's now an option (as of 1.7) where you can choose the Serana Hood animation, the Quick Feminine animation, or one at random. You need to download the appropriate animation. See below:

Serana Hood Animation by chikuwan:
Chikuwan has some awesome open permissions on his mod (Serana's Hood Fix with Animation) that I've used. You can either download that mod or the extracted animations I've included in the miscellaneous section. Make sure you refresh your FNIS, Nemesis, or w/e you use. If you use the extracted one, give them some kudos on their profile.



Quick Feminine Animation by corvoassasin12:

Corvoassassin12 has made these animations specifically for this mod from scratch and asked me to host them. They're amazing and I'm honoured to have them as part of this mod. They may be building more as well. Make sure to go to their profile and give them some kudos.



Q & A

Can We Pick the Locations?
- You can edit the formlist using TES5Edit. You can turn off location toggles completely as well.

Hot Key?
- Added in v1.1 as I was debating it anyway

Supports All Hair Types?
- If you can select it in RaceMenu, it should be supported
- Use the "Check" option in the MCM to make sure the mod can detect the hair style you're wearing. Wigs probably won't work.

Supports Males & Females?
- Yes it should, but I haven't tested males personally. (It does support males! I, the backporter, only play males and the mod works perfectly.)

Followers Supported?
- No, sorry. It won't persist anyway I don't believe. Also I don't use followers and I find them a pain to work with in mods. If you can tell me a quick and clean way to fetch your followers via papyrus, I might add more follower support in the future.

Hair In Pictures?
- Dint999 (patreon)

Known Issues - These will not be fixed unless someone presents a solution

Facial Expressions
- Facial expressions can stop working when using this mod. I don’t have a fix. Honestly, why are you staring at your character’s face so much anyway.
- Note, apparently some SMP hairs can cause this. Play with your hair combos a bit.

Invisible Body Body:
- Apparently the new Faster HDT-SMP version has significantly reduced this / eliminated it.
- Quick solution: Save and reload. Sometimes works. 
- More in depth: Its a hair thing, see this Faster HDT-SMP article/blog/thing.

Temporarily Invisible Eyebrows / Teeth:
- Apparently the new Faster HDT-SMP version has significantly reduced this / eliminated it.
- There’s been a lot of testing and discussion about this. The bug exists without this mod occasionally, but gets exacerbated by the hair switching, sometimes. It might pop up here and there, but it’ll go away too. 
- Opening and closing racemenu or saving and loading might help.
- Comments in the discussion pointed out its a common smp bug and that if your teeth disappear they're probably hovering high above your head.
- You can try playing with different smp hairs, apparently some are worse than others for this.

Doesn’t Work As A Vampire (kinda fixed):
- I know, it sucks. This has to do with how the vanilla vampire is enforced somehow. I’m still investigating if I can override it. It seems so far that you're stuck with one hair for your duration as a vampire. Big thanks to TVzwordz for doing a lot of initial testing on this.

- I've created a workaround for this.
- Racemenu doesn't work as a vampire for some reason. What the mod does now is check if you're a vampire, convert you to your non-vampire equivalent for a second, switch your hair, and convert you back.
- This only supports the base 9 races in skyrim. If you would like to add a custom race, add the vampire race to the LetYourHairDown_VampireRaces formlist and add the non-vampire race to the LetYourHairDown_PlayableRaces formlist at the same index.
- If the microsecond flash that may occur isn't to your fancy, don't mention anything, just turn the mod off if you're a vampire. Seriously, just don't say anything. I did this fix as a courtesy and I don't care about the slight quantum moment of immersion loss in this case.

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For more information, please see Let Your Hair Down modpage and don't forget to endorse the original mod!

Thanks to FarmingDarkness for letting me backport this gem of a mod.
Hope you all enjoy it as I am.