Back in the 70s, author Tom Wolfe coined the term "post-orbital remorse" to describe the depression that some astronauts experienced after returning from space missions.
Once you'd ridden into space in a rocket, Wolfe wrote, nothing else you did would ever live up to the experience. Life would seem dull and flat, even those things you'd previously found exciting. You had, after all, loitered on the lunar surface: your life had peaked.
I haven't been to space, and I'm not ready to answer the "has my life peaked" question, but having returned from a second stint overseas, I once again find myself in post-travel depression's waiting room. Experts refer to it as Reverse Culture Shock, the confusion and restlessness some expats experience when returning to their native country.
After adjusting to a new culture for an extended period of time, they say, there's the need to physically, emotionally and mentally flip another switch when you return home.
Like so many before me, as soon as I'd cleared university and my first job, I threw money at a one-way ticket to London. It was a two-year stint that effortlessly morphed into four: four years of speed-dating with different postcodes and tube lines, four years of dodging reality with unsuitable jobs and ill-advised boyfriends. There were camel rides in Cairo, wild cherries in Chile and hangovers in three different continents.
I eventually returned to New Zealand with an expired work visa, an empty bank account and a husband. But wrenching myself from all that was familiar was tough and we spent a good year playing the "should we stay or should we go?" game (apologies to The Clash).
As my husband described it, coming home was like wearing contact lenses in the wrong eyes - familiar, but not quite right.
While we'd been away friends had developed a sweet tooth for mortgages and babies, for careers and power tools. They asked "how was it?" as though we'd been on holiday for a couple of weeks, the subtext being that they had galloped away to a grown-up place where there was little room for our life-changing experiences.
One night at a friend's house, there was an item on the news about Moscow. "A homeless guy trying to sell me a block of hash once chased me into a Moscow subway," I said.
Everyone looked as me as though I'd got off a spaceship instead of a plane. But I wasn't being boastful, it was a true story that had been triggered by the news item. I learned to keep my mouth shut.
On my daily commute to work, as unhappiness clung to me, I cried hopelessly for the life I had lived. I grasped at anything that could break my fall - including schlepping across Auckland to visit a psychic. "Will I ever live in Europe again," I asked her? "No," she said.
"You will return for weddings and holidays, but you will never live in the Northern Hemisphere again." It later transpired she was wrong, but at the time it was enough to soothe me.
We rescued a dog from the SPCA because I'm better with canines than I am with children, also because I knew that committing to a living creature would help tether me to New Zealand.
And so we waited it out, we sat with the discomfort, rubbed the sharp edges smooth with our daily routine and eventually stopped thinking of "home" as somewhere else.
And then a few years ago, my husband landed a contract with the Bristol-based film studio responsible for Wallace & Gromit and we were faced with the decision of moving back to Britain for a couple of years. I wasn't convinced: I had finally built my new life in Wellington, had a lovely house, lots of freelance work and hubby was animating The Hobbit.
But it was too good an opportunity to refuse, so once again we dismantled the scaffolding of our lives and moved across the globe. The contrast to my first OE couldn't have been more different: I arrived to a country folding in on itself, where jobs were hard to come by and even harder to keep. Yet despite being made redundant twice in six months, it didn't take long for Europe to creep into my heart and curl up there.
I made new friends and studded my passport with stamps like cloves in an orange. Once again, I felt the delicious joy of being adrift from real life, of not having to be responsible for anyone but myself.
We got possibly the ugliest flat in Bristol for £750 ($1400) a month, but it was a relief to delete the Martha Stewart tendencies I'd spent years acquiring. For the first time in a decade, I didn't have to come home at a sensible hour to feed and walk dogs, so I stayed out longer than any sane person should.
It wasn't as though I wanted to be 25 again, but after so long of being sensible it felt good to drift from bar to bar, from country to country, because I could.
But after 18 months, the party ended and my husband was headhunted back to Wellington. And post-travel depression rushed towards me again, arms outstretched.
This time, it has been slightly easier: muscle memory knows how to deal with the gnawing sense that I've settled for half a life, to remind me to be happy for - rather than rabidly jealous of - friends who bother Facebook with images of themselves lounging on Caribbean beaches or wandering through Moroccan souks, and who email to ask if I think a weekend in New York or Tuscany would be better. There have been good days, and days where it feels as though I've abandoned the world.
Fortunately, the "harden up" brigade has been at the ready - with advice, activities ("you really should join our book group") and endless patience. I'm also fortunate that the New Zealand economy has been kind, letting me slot easily back into work.
In the end, there has been nothing for it but to hitch up my skirt, slap on a smile and get on with it. I can't change the past - nor would I want to - but it does me no good to keep walking around in it.
One thing I do know is that with time, the enemy will be defeated and I will find my way back to my turangawaewae.