Tonight I will go to bed when I am tired, and tomorrow I will rise when I please: My Mars time experiment is over.

For five weeks I’ve stayed put geographically, but my circadian rhythms have marched westward, advancing two-thirds of a time zone each morning to match the 24.65-hour day of our neighbor planet. So my days have been longer but there have been fewer of them. In 36 days, I’ve had 34 sleeps.

If I was to write a scientific paper on this unscientific experiment, the results would state that I was indeed able to adjust to a longer schedule, with periodic sleep deprivation that was generally annoying but not terrible, probably less than what the average parent of a human infant has to put up with, though that didn’t stop my relentless whining.

During this period I suffered a handful of fatigue-induced headaches, many days of confused appetite, and one cold (which has only descended in the last two days, as my schedule is finally back to normal, so causation is questionable). I did not walk under a bus, as Harvard sleep scientist Steven Lockley warned I might, but the experiment did exact one badly stubbed toe from wandering around my apartment with my eye mask on like an idiot.

All in all, my Mars time experiment wasn’t exactly beneficial to my health, but it hardly killed me.

It was all easy when it began. I started with my normal-ish schedule, going to bed at 2 A.M., rising around 9 A.M., and pushed those times back 40 minutes each night. But by the second and third weeks I was staying up well into the middle of Earth’s day, and attempting (often in vain) to sleep through the afternoon and into the evening. With the help of some hand-imported Peet’s coffee I managed to stay up alright, and when bedtime finally came around, I was usually sleepy enough to doze off for an intense few hours. But longer sleep proved evasive.

I had vivid dreams in this period, including one that featured aliens who smugly told me I would never finish my Mars time task, and I woke up feeling like a failure. Another involved an earthquake that spun the entire world in circles. I awoke and realized that indeed there was an earthquake occurring. I laid there watching the wall-hanging above me swing side to side, and then slow to a sway, and then I was back asleep.

I spent much of this phase wandering Santiago streets trying to stay awake till dawn, when the sun would finally do its melatonin-suppression trick and help me stay awake. You notice things about your neighborhood when you walk it in the middle of the night. For a year and a half, I’ve walked nearly every day past a hospital emergency room. But only in the quiet of the night did I stop to watch the paramedics’ faces as they wheeled empty stretchers back to their ambulances, cigarettes sagging from their lips. Through the E.R. window I peered at 4 A.M. patients. A little boy’s sleeping face jiggling on his pacing father’s shoulder. An aged television blaring some cop show that nobody was watching.

By week 4, I was falling asleep at 5 or 6 P.M. and waking at 1 or 2 A.M.; my body seemed willing to sleep more hours on this schedule, when I let it—but letting it was the rub. As the experts warned me at the beginning of my project, the toughest part was accommodating my strange schedule to the demands of an Earthly social life. One night I found myself up hours past my Martian bedtime, celebrating a dear friend’s birthday at a dinner party his boyfriend was hosting. Many of the guests were his boyfriend’s clients, wealthy Chilean women in their 50s and 60s, champagne-loving divorcees who call themselves Catholic but show much more enthusiasm discussing numerology than Jesus Christ. When I finally excused myself from the party, head spinning from Kir Royales, one of the ladies asked why I was leaving so early, and the whole room turned to look. Um, because I’m pretending to live on the schedule of Mars, which is, like, different than the Earth schedule, and it’s my bedtime now, I said, struggling with the explanation in my exhausted, drunken Spanish. They nodded politely and then turned to look at each other with their well-groomed eyebrows raised. I blushed as I noticed how absurd I sounded.

That was in contrast to my 3-year-old niece’s response a few days before, when I told her I had to go home and go to bed in the middle of the afternoon. “Why?” she asked. Because I’m living on the schedule of another planet. She nodded thoughtfully, and then asked if I would do a puzzle with her before going back to my planet.

This last week has been easier again; I’ve taken down the tinfoil from my windows and no longer need my shoddy airline eye mask, because I’m going to bed after dark and getting up in the morning. It’s been strange and delightful to feel tired at 10 or 11 at night, since for the majority of my adult life that’s when I should have been going to bed, but invariably has been when I feel most awake. That schedule was still getting me up in time to watch the sun rise over the Andes, a special and treasured gift this experiment has given me. Now that I’m all the way back to going to bed at 2 A.M. there are no more sunrises.

Many real science experiments have explored what it might be like to live on the Red Planet: There are Mars analogue stations all over the globe, in which scientists try to simulate various aspects of an interplanetary mission. One such experiment will embark next month on the slopes of Mauna Loa on the Big Island of Hawaii, where a crew of six will live in a simulated Mars habitat for four months. Their mission: Figure out how to cook on Mars. Among the study participants is crew journalist Kate Greene, who will be investigating how the members’ sleep cycles are affected by Mars time—so if you’re interested in more discussion about circadian rhythms on other planets’ schedules, check out her blog here starting early April.

As for me, I’m looking forward to telling my niece that I’m back on Earth, for good.

Previously in this series:

Stepping into the Twilight Zone: Day 33, or, Curiosity Killed by a Cosmic Ray

Step into the Twilight Zone: Can Earthlings Adjust to a Longer Day on Mars?

Step into the Twilight Zone: Day 1

Step into the Twilight Zone: Day 4 on Mars Time, aka Easy Peasy Lemon Squeezy

Step into the Twilight Zone: Day 8 on Mars Time, aka Camping on Mars (Time)

Step into the Twilight Zone: Day 11 on Mars Time, in Which I Give Myself Cancer

Step into the Twilight Zone: Day 15 on Mars Time, or Adventures in Extraplanetary Day Drinking

Step into the Twilight Zone: Day 18, Cuddle Cafes and the Dangers of Dozing

Step into the Twilight Zone: Day 22 on Mars Time – Meteoric Changes to the Earth Day, as Told by a Thousand Tired Decisions

Step into the Twilight Zone: Day 25, or A Walk Through Santiago’s Witching Hour

Step into the Twilight Zone: Day 29, or God in Outer Space