By Laura Newberry

I’m one of those people who’d be living my best life if I slept nine hours a night. Unfortunately, I’m also a person with a hamster wheel in my brain that starts spinning the moment my head hits the pillow. It can take me a while — sometimes a long while — to quiet my thoughts, so I don’t get my optimum amount of sleep a lot of the time.

When I got this question from a reader, I deeply related. Knowing what I know about the modern human condition, I bet a lot of you will, too:

“Recently, I have had a hard time sleeping. Every time I close my eyes, there’s always something that comes to mind … even things I shouldn’t think about just come out of nowhere. I often make scenarios of my life before going to sleep; in other words, I often imagine creating my own world in my subconscious. I wonder what a therapist would think in these circumstances.”

I talked with three experts about why our minds race as we’re trying to fall asleep, what that incessant whir of thoughts has to do with insomnia and what we can do about it.

Why we need sleep and what happens when we don’t get it

The importance of sleep is something innate to us. When we don’t get enough of it, we really feel it — we’re moody, irritable, exhausted. Our immune systems don’t function as well so we’re more likely to get sick. The term “run-down” comes to mind.

Why does this happen?

For the most part, the biological purpose of sleep remains a mystery. Yet scientists do know that a lot goes on when we’re in the abyss of slumber. “Sleep is actually a very active period in our lives,” said Emily K. Fitton, a psychotherapist in New York who specializes in sleep issues.

Recent research suggests that sleep is like a waste-management system. The flow of cerebrospinal fluid in the brain increases dramatically and sweeps away toxins that build up during your waking hours. When this system underperforms, it may play a role in brain disorders such as Alzheimer’s.

Sleep may also help us consolidate our memories, transforming them from transient thoughts to memories that can be accessed years later. “Much of this consolidation occurs during Stage 2 sleep, a light sleep phase that occurs most in the hours prior to awakening. This means that if you get up early without a full night’s rest, you may be impairing your ability to hold onto your memories,” writes Dr. Andrew E. Budson for Harvard Health.

Sleep deprivation reduces concentration and attention, making it harder to retain information and use it when we really need to.

In short, sleep affects almost every type of tissue and system in the body — from the brain, heart and lungs to metabolism, immune function and mood. Research shows that a chronic lack of sleep or regularly getting poor sleep increases the risk of high blood pressure, cardiovascular disease, diabetes, depression and anxiety.

In the first experimental study of sleep deprivation in 1894, puppies were forced to stay awake through constant stimulation. They died within five days.

“The total absence of sleep is more fatal for the animals than the total absence of food,” wrote the study’s author, Russian scientist Maria Manasseina.

What causes sleep difficulties?

So many things can get in the way of a good night’s sleep. But here are some of the most common factors that can lead to tossing and turning or, in the longer term, insomnia, according to experts:

-Your sleep space is noisy, or there’s too much light.

-You regularly drink caffeine and/or alcohol in the hours leading up to bedtime: A night of drinking will interrupt your phases of sleep. Though it initially might help you pass out, it actually activates you in the latter half of your night, and may cause you to wake up several times.

-You’re stressed or anxious: I know this one is obvious, but stress can hugely affect sleep. When we’re worried about work deadlines, how we’re going to pay the bills, or if we’re in any kind of unsafe situation, the brain triggers a flight-or-fight response (otherwise known as survival mode). Thanks to a surge in hormones such as adrenaline and cortisol, your blood pressure increases, as do muscle tension, heart rate and alertness levels.

And poor sleep creates even more stress, causing the body to act as if it’s in danger and triggering a vicious cycle of sleeplessness.

-You’re depressed. An estimated three-quarters of people with depression have a hard time falling asleep or staying asleep. As with stress and anxiety, depression and insomnia have a reciprocal relationship. “Poor sleep may create difficulties regulating emotions that, in turn, may leave you more vulnerable to depression in the future — months or even years from now,” according to Johns Hopkins sleep researcher Patrick H. Finan. “And depression itself is associated with sleep difficulties such as shortening the amount of restorative slow-wave sleep a person gets each night.”

It’s important to note that stress itself isn’t what sustains insomnia. Our anxiety about whatever is going on in our lives gets shifted to our sleep, said Virginia Runko, a psychologist and sleep specialist in Washington, D.C. We try to make up for lost shut-eye by sleeping in and taking naps during the day, measures that can disrupt our circadian rhythms and make it harder to drift off at night. And then we start associating sleep with worry about sleep deprivation, and on and on.

Why do our minds race at bedtime?

Our reader writes that he “creates his own world in his subconscious” as he’s trying to fall asleep and that thoughts “just come out of nowhere.”

Again, relatable. I asked this week’s experts why it’s common for our thoughts to pinball around frantically at night, even if we’re quite tired.

“Many of us are busy all day, every day, and some thoughts get suppressed because we’re just dealing with what’s in front of us right now — putting out fires, cleaning, cooking, taking care of children,” Runko explained. “Your first moment of quiet might be when your head hits the pillow.”

The thoughts that weren’t given the space to be processed or appreciated during the day make themselves known — and then some.

“People sometimes think they can go from 60 miles per hour to zero and just fall asleep,” Fitton said.

The more nights you’ve spent lying awake and thinking, the more your bed becomes associated with wakefulness, Fitton said. This is also true if you watch stimulating TV shows, have deep conversations with your partner or do work in the same place where you sleep.

“The brain will say, this is a place we stay awake and think,” Fitton said.

How to get your sleep back on track

If sleeplessness has become persistent and is affecting your relationships, work or other areas of your life, you may want to see a sleep specialist, experts said.

Primary care physicians are likely to prescribe medication; the percentage of people using sleeping pills in the United States has doubled since 2010. Sleep aids such as Ambien and Sonata can help if insomnia is especially severe, Runko said. But she and many others sleep specialists see these medications as a short-term solution because they don’t treat the cause of insomnia, they often become less effective over time and they come with notable risks.

In its guidelines for insomnia treatment, the American Medical Assn. recommends trying CBT-I (Cognitive Behavioral Therapy for insomnia) first. “If that doesn’t work, then you might need to have a conversation with your doctor about the pros and cons of medication,” Runko said.

Antidepressants or anxiety medications may also help if those conditions are at the root of insomnia, Runko added.

Short of going to a sleep specialist, here are some lifestyle changes you can make to better your sleep, according to our experts:

If possible, keep work, TV, and phone time out of the bedroom. I know … much easier said than done. “The only two activities in bed should be sleep and sex,” said Darshan Mehta, medical director of the Benson-Henry Institute for Mind Body Medicine and assistant professor of medicine and psychiatry at Harvard Medical School.

-Have a wind-down period before bed. “Give yourself permission to let go of the day,” Fitton said. “Process thoughts before you get into bed; talk to your partner, write in a journal, so that when you’re in bed and a thought comes up, you can tell yourself, ‘This is not the time for thinking. I’ve already dealt with it — no problem.’”

-If you can’t sleep, get out of bed. Redirect your attention away from your racing thoughts onto a book, TV show or podcast — in another room. “Make a nice cozy nest for yourself somewhere else, and try not to feel terrible about it,” Fitton said. This is one of the ways you’ll de-condition the bed as a place of thinking and frustration, and you’ll release some pressure on yourself to fall asleep right this moment. This can work because anxiety about sleeping is the enemy of sleep; antithetically, if you give up on sleeping and thinking about sleep, you’re way more likely to fall into a deep slumber.

-Start a mindfulness or meditation practice: This is another way to step away from the hamster wheel of your thoughts, and my personal favorite. The general gist of it is noticing your in-breath and out-breath and/or sensations in your body, and allowing thoughts to come and go, almost as if they don’t belong to you. You might also try a body scan or progressive muscle relaxation.

Runko recommends trying these practices during the daytime first, and then using for sleep as needed. That’s because these practices might not help with sleep right away — they do, as the name suggests, take practice — and we don’t want to associate beginner’s frustration with bedtime.

One of the paradoxes of sleep is that the more we fixate on getting it, the less likely we are to achieve it. “People really need to dial down the anxiety about sleep,” Fitton said. “The harder you try, the worse it gets.”

Sheesh. No wonder getting your sleep back on track can be tricky. Though, I’ve found some peace in knowing that the acceptance of insomnia is key to managing it. I’ll try to remember that the next time I’m fighting for some shut-eye.