The last time I remember experiencing symptoms of insomnia was in the week or so leading up to a move. It was a move I was excited about (to a first house with my husband) but I was also really stressed—my head full of details and loose ends to be dealt with, of anticipation for moving day and all the work to be done in the new place. I’m a pretty good sleeper generally, but I had a number of restless nights leading up to our big move. I was so wound up at night I had trouble falling asleep, and my eyes would shoot open hours before I’d typically be awake.

Insomnia is like that. It can pop into your life out of the blue, often in response to changes or upheaval. Like with my move, the changes don’t have to be unwelcome ones to bring about sleeplessness. Insomnia can also happen because you’ve made some change to your routine or your sleep schedule. Traveling through time zones, even switching the clocks for daylight savings time can be enough to throw your sleep schedule off course, and leave you staring at your ceiling late into the night.

This is what sleep experts call acute insomnia. It starts suddenly, and the reasons behind it are often pretty clear. This kind of insomnia typically resolves itself, usually within a few days or at most, a few weeks. Most of us are likely to have some experience with this kind of insomnia in our lifetimes.

But what is insomnia, exactly? It’s an inability to sleep when you’ve got the opportunity do so, and it has a few hallmark symptoms:

  • Difficulty falling asleep
  • Difficulty staying asleep throughout the night
  • Waking very early in the morning

Insomnia doesn’t always crop up in response to a life event. And it doesn’t always recede after a few days or a couple of weeks. Insomnia that lasts for a month or more is considered to be chronic. It’s not always clear what’s behind a person’s chronic insomnia. Sometimes it may be a side effect of another illness, or of medication. Stress can be a factor. So can keeping odd or irregular hours—staying up very late or getting up very early, or changing around your sleep schedule frequently.

There are also possible causes of insomnia in our daily habits and in our environment—especially our sleep environment. Too much caffeine throughout the day can trigger symptoms of insomnia; so can drinking alcohol too close to bedtime. Eating heavily in the evenings can disrupt sound sleep as well. Exposure to artificial light at night—your phone, your computer or tablet—can throw off your body’s natural sleep routine, and lead to difficulty sleeping. A dark bedroom is a great boon to good sleep—that means blocking light from outdoors as well as light inside the room itself. TV in the bedroom? As relaxing as it may feel to drift off to those always-running episodes of Law & Order, it’s probably not doing good things for your sleep.

If you’re troubled by any of the symptoms of insomnia, a check-in with some of those lifestyle habits, and a look at your sleep environment, is a good place to begin looking for solutions. I settled into a sleep routine in my new house and my new bedroom—but I’m glad I know what to look for the next time I’m wrestling with those symptoms.