A few weeks ago I was in Mexico, and slept nine nights in my sleeping bag on my friends’ front porch. My sleep was not without middle-of-the-night wakings, but I easily released back into sleep after each one. The rhythm of a life lived mostly outside, and mostly without a timepiece, agrees with me. While there, and against the odds, I got some of the best sleep I’ve had in years.

If you’re between 40 and 60, and you or someone you know is getting a good night’s sleep, raise your hand now.

I bet a million bucks you didn’t raise your hand, and not because you’re sitting at a table at Macy’s with a raspberry oat muffin and a double cappuccino. It’s rare that any of my adult friends (and especially the women) can lay claim to a full night’s sleep without the aid of some pharmaceutical or other.

I personally am a member of the 2:30 Club. No matter what time I go to bed, or how much exercise I’ve gotten or how many cups of coffee I’ve drunk or not drunk, I wake up, look at the clock, and it’s 2:30 a.m.

If this happens to you, you might decide to search for “sleep deprivation” on the Internet. Google will instead suggest the lyrics for a song called “Sleepyhead.” (And if you happen to follow that link in the middle of the night, and then, because the lyrics are somewhat interesting, you decide to listen to this song, I recommend you turn down the sound on your computer. The people singing it sound like their lungs are full of helium.)

If you persist in your research, here’s some of the advice you will be offered: Get out of bed and do something productive until you feel sleepy. Stay in bed, but turn on your lamp and read. Drink some warm milk. Whatever you do, don’t turn on any lights. Don’t look at the clock to see what time it is. Don’t look again 10 minutes later to see how much time has passed. Don’t check your e-mail to see who else is awake and online.

In other words, any action is futile.

Also online, you might learn that symptoms of sleep deprivation include attention lapses, reduced short-term memory capacity, impaired judgment and in extreme cases, hallucinations and delusions.

It’s 2:30. I’m awake, but not yet delusional.

The moon is full, and I can see that the ponderosas behind our house are—much like my brain—shrouded in fog. The sound of the train whistle comes in the cracked window, even though the tracks are more than a mile away. How is it that sound can travel such a great distance when light gets caught so exquisitely on the moisture in the air?

Tonight I’m afraid if I turn on the lamp I’ll break the spell of the milky light on the pines. So I lie awake in the dark and watch out the window.

I can’t think what the answer might be.

I do know that though the impulse to wake comes in the guise of leg cramps, or a full bladder, or a hot flash, what keeps me awake is more complicated and difficult to fix. Even if I can successfully circumvent certain things during the day and evening, they will wake me gently or violently in the night. They are persistent and unrelenting: goblins of worry, niggling trivia or bothersome self-doubts. Every one of them balloons to fill the room, jostling against each other for a position next to the bed.

I turn on the light, pick up my journal, and remember how good it was to sleep in Mexico.