The TV presenter, who gave birth to her second child Honey Krissy on 9 September, is suffering from her daughter being a "night owl."
Cotton posted a photo of her hair whipped up in a messy bun on top of her head - a look many mums will know well.
She captioned the photo: "Honey certainly lived up to the Wood family name last night. #nightowl #mumhair".
Cotton's photo prompted other mums to share their #mumhair moment on Instagram.
One mother commented: "I'm in the same boat @fearnecotton my little gingerbread kept me up too. So I was donning mum hair whilst taking my biggest little to nursery at 8am."
Another added: "Haha my son is six months and my hair pretty much looks like that everyday!"
From looking at the hashtag on Instagram, Cotton is not the first to debut this top knot hairstyle as the stereotypical #mumhair. These mums have too.
Aside from tackling the lack of sleep, life with Honey seems pretty sweet.
Cotton recently uploaded a photo of her guitarist husband Jesse Wood "serenading" their newborn daughter. Bless.