Does the cry it out method for sleep training work for nearly 4 year olds?

Asha will be 4 in July. We have had maybe a year, between 2 and 3, where she slept well. From 7pm until 6.30am, straight through. This took 6 months to 'train'. From a clingy baby who had to be rocked and held to sleep, and woke every 40m to be soothed again. Each time we knew we were making it worse, but we were too soft. When she got too heavy to rock, we tried the Ferber method and after 4 days it worked! She slept so well for a whole year. Then she started school, caught a snotty, chesty cold, and bam...sleep schedule ruined. It's been almost a year now, of crying at bedtime until she vomits, anything up to 8 wake ups a night, co-sleeping, sitting beside her until she sleeps and doing the ninja escape...until you step on a loose floor board, and round we go again. We have tried bribery (rewards system), the Ferber method again, cry it out (we lasted 32 minutes), mastered the ultimate wholesome bedtime routine for years, and even begging. Our last resort came last weekend when hubby and I decided to try camping. We had loosely agreed that we should veto bedtime and just see if she will drop by herself and enjoy family time. She stayed up until sundown at 10.33pm..! Back home again, and we royal gave up. No more energy left to fight it. She wins, no more bedtime. By 7.50pm, 20 whole minutes passed the old bedtime, she was asking to go to sleep. Asking! She still woke at 2am and 4am, but went back to sleep quite quickly. But we will happily take that. We are very broken parents now though. From 6pm we start to get anxiety over the up and coming out down. We are jumpy, grumpy, fidgety, paranoid at every sound, and absolutely freaking out all night at the fear that she won't sleep well. My hubby has gone grey and I am a full blown insomniac now. I'm 92% certain all this worry of sleep has rubbed off on Asha, over the last few months, and she likely worries herself over waking. Poor love! Funnily enough, however, the lack of or disturbed sleep never seems to affect her the next day; bouncy as ever and never understands why mummy can't play tag for long anymore.We have tried everything except the cry it out method. Hubby isn't keen, but I start a new job next week, and this can't go on. Ideas? via /r/Parenting https://ift.tt/3pGa2I7