And up until now, we just didn't know how she managed it. Red carpet events, countless trips abroad and glamorous parties on school nights? If that was our schedule, we'd look like we'd been dragged through a hedge backwards...
But on Wednesday (2 November) the reality star Instagrammed her latest beauty trick for always ensuring a good night's sleep.
"Obsessed with this @superelixir calming mist before bed #sleepwell," she posted, along with a picture of her new overnight beauty must (below).
Aha, so that's how she does it.
Millie's bedtime beauty secret is none other than The Super Elixir Sleep Welle Calming Mist, £24, welleco.co.uk, part of former supermodel Elle Macpherson's range of beauty lust-haves.
Containing lavender, vetiver and chamomile oils, a few spritzes of this bad boy promises to help reduce tension and anxiety to encourage a beautiful sleep, every time.
And it clearly works if Millie's constantly glowing skin, sparkly eyes and fresh-faced beauty is anything to go by. Get. Some. Now.
We also love Champneys Good As News Heavenly Days Sleep Pillow Mist, £11, boots.com which contains similar aromatherapy oils.
And This Works Sleep Balm, £12, boots.com is another great choice is you'd prefer a balm that you apply to your pulse points instead...
ps: How amazing do Millie's nails look in her Instagram snap? Sigh.
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