Wanting to fall asleep but not being able to is an incredibly frustrating experience. It’s also an extremely common one. In fact, doctors are seeing this type of insomnia so frequently these days, it’s like an epidemic, says Joanne Pizzino, MD, MPH , a physician with Parsley Health. “The more stressful the world we live in, the more it affects our sleep,” she adds.
If you’re wondering why it’s so bad for your health when you can’t fall asleep, the answer lies with the autonomic nervous system. It runs everything in the background, Dr. Pizzino explains: beats your heart, controls your blood pressure, makes hormones, and digests your food.
The system has two branches: the sympathetic nervous system (also known as the “fight or flight” response), and the parasympathetic nervous system (also known as the “rest and digest” impulse).
The sympathetic nervous system is only supposed to be activated for short periods of time when we experience a threat, with the majority of our time spent in the parasympathetic state. “But in our modern world, we tend to be in this 24/7 turn-on-the-sympathetic-nervous-system thing due to stress and other factors,” Dr. Pizzino says.
To understand how this affects our health, a quick example is helpful:
“When a gazelle is running away from a lion, it doesn’t stop and take a nap,” Dr. Pizzino says. “It doesn’t stop and digest its food. It doesn’t stop and make a baby.” The gazelle uses the rush of adrenaline from the sympathetic nervous response to get away from the lion. “And then if you actually watch the gazelle once it’s safe, it’ll stomp the ground and shake, because it has to discharge this enormous amount of energy that it just used to save its life.” That’s the sympathetic nervous system shutting down, making room for the parasympathetic nervous system to do its thing.
But most people never “discharge” that sympathetic energy, which means we aren’t nearly as effective at the activities we’re supposed to do in the parasympathetic state. Many of these activities happen while we’re asleep, or can’t happen unless we get enough sleep such as reproducing, boosting our own immunity, digesting our food, and making the hormones our bodies need in the right amounts.
Not being able to fall asleep in particular is a pretty reliable sign that the sympathetic nervous system is out of whack. It can also set off a chain reaction and self-perpetuating cycle: trouble falling asleep means not enough sleep, which means the body isn’t recovering or working the way it’s supposed to, which in turn makes it harder to calm down and fall asleep.
Ahead, Dr. Pizzino breaks down why you can’t fall asleep at night, plus what to do about it.
When a patient can’t fall asleep, Dr. Pizzino first asks about what they’re doing in the hours leading up to bedtime. “Sometimes, people are staying up and answering emails and things like that because they know they don’t fall asleep, so they know they need to occupy themselves until they get tired.”
Especially for parents with young children, people sometimes stay up to get important tasks done before bed. Then, they find themselves having trouble going to sleep when they’ve finished, “So teasing out how much of staying up is voluntary and how much of it is something physiologic going on can be important,” Dr. Pizzino adds.
If after reflection, you discover this is your problem, finding another time to do these tasks and/or developing a nighttime routine can help.
You probably know that you’re supposed to go to bed and wake up around the same time every day. This isn’t always easy to achieve, but the more regular you can get, the better, Dr. Pizzino says. If you’re consistent enough with your bedtime, your body will eventually learn when it’s supposed to fall asleep.
For those trying to adjust their sleep schedules to be more regular, it’s important to do it gradually, Dr. Pizzino says. So if you normally fall asleep at 1 am, but you’re looking to change to 10 pm, start by adjusting your bedtime to 12:30 am. Then, gradually push your bedtime 30 minutes earlier every one or two weeks.
Naps can also have an impact on your ability to fall asleep. Some people may find power naps (ones lasting less than 30 minutes) to be helpful, but anything longer than that is likely to make it difficult for you to fall asleep at night, Dr. Pizzino says, so for most people, long naps should be avoided. If you find naps are necessary because you’re tired all the time , there may be something deeper going on.
If you feel exhausted but can’t sleep, this might be the issue you’re dealing with. “We call it wired and tired,” Dr. Pizzino says. “This is probably the most common thing I see with patients who can’t fall asleep.”
We already covered how stress affects the autonomic nervous system. “Part of that is what’s called the hypothalamic pituitary adrenal axis, or HPA-axis,” Dr. Pizzino explains. The hypothalamus, a part of your brain, and the pituitary gland control the adrenals, which produce cortisol , our stress hormone. “Cortisol goes up in response to physical, mental, and emotional stress,” Dr. Pizzino explains. Increased cortisol makes it even harder to get into that “rest and digest” state, making it difficult to fall asleep.
If your doctor suspects this may be your issue, they can test your levels with a 4-point cortisol test that measures your cortisol levels throughout the day. For optimal sleep, your levels should be lowest when it’s time for bed. If that’s not the case, Parsley Health’s doctors and health coaches work with members to naturally lower your cortisol levels .
“Chronic inflammation is probably the biggest health issue in the modern world,” Dr. Pizzino says. ”When we’re inflamed, the body sees that as an alarm system.”
If you think back to the example earlier, we mentioned that the gazelle doesn’t make a baby while running away from the lion. “Our sex hormones and thyroid hormones are among of the first things that are impacted in a sympathetic state, Dr. Pizzino says. This can cause hormone imbalances , which can play into energy levels and circadian rhythm, potentially wreaking havoc on our ability to fall asleep.
One hormonal imbalance that especially affects the ability to fall asleep is low progesterone in menstruating women (which can happen alongside higher-than-normal estrogen levels). “Progesterone, which is a calming hormone, is the direct precursor to cortisol. So when we’re under a lot of physical, mental, or emotional stress, we often don’t have enough progesterone,” Dr. Pizzino says.
If you notice sleep issues that coincide with your menstrual cycle, that’s a red flag that this may be an issue for you. And if you’re beyond cycling and you’re into menopause, hormone deficiencies may also be at the root of sleep issues.
The HPA-axis can also get out of whack due to physical stress, and one physical stressor that people often miss is hidden infections and viruses. Everything from parasitic infections to tick-borne diseases, viruses in the herpes family such as Epstein-Barr virus, cytomegalovirus, and the herpes zoster virus can cause undue stress on the body, Dr. Pizzino says.
These are referred to as “hidden” because they’re really good at avoiding the immune system , which makes diagnosis and treatment tricky. Aside from having trouble falling asleep due to revved-up cortisol, the most common sign this could be an issue, according to Dr. Pizzino, is not feeling rested even when you do get enough sleep. Other signs include flu-like symptoms in the absence of a fever, brain fog , and musculoskeletal pain (which may also make it difficult to fall asleep).
“Digestive issues contribute immensely to problems falling asleep,” Dr. Pizzino says. In particular, eating too much too close to bedtime is problematic. Because of our circadian rhythm, we’re really not supposed to be digesting after about 8 p.m at the latest, according to Dr. Pizzino. Of course, feeling uncomfortably full could be contributing to why you can’t fall asleep. But there’s another reason it’s best to have an earlier dinner: “When we eat late at night, it literally pulls blood away from the brain and other places that are supposed to be working while we sleep.” That might make it difficult to fall asleep and stay asleep.
Gut health gets a lot of attention, for good reason. A lot of important neurotransmitters—chemical messengers in your nervous system—such as serotonin and GABA, are made in your gut. “GABA is particularly important for sleep because it’s the only calming chemical in the brain,” Dr. Pizzino explains. “When we don’t have enough GABA, that’s when we get anxiety and have trouble sleeping.”
When your microbiome is out of balance, with more “unfriendly” flora than “friendly” flora, your body literally sees that as a threat, Dr. Pizzino says. “Are you going to be able to fall asleep if you think that there’s something dangerous out there? Probably not.”
The good news is that there’s a lot you can do to improve your gut health , from dietary modifications to taking a proven probiotic, both of which can be done with support from your health care team.
“Alcohol tends to be one of the big slip-ups with sleep because people often use it to help them turn off that sympathetic nervous system and calm down,” Dr. Pizzino says. Because alcohol is an anesthetic, it takes your brain waves down into a more relaxed state. But when that effect wears off, the brain waves start getting overactive again, causing you to become alert. Depending on how you time your alcohol intake, this could either cause you to have a hard time falling asleep, or wake up in the middle of the night .
For this reason, it can help to take a break from alcohol until your sleep issues are worked out.
“A lot of people don’t appreciate how much the coffee they drink in the morning is still affecting their body at night,” Dr. Pizzino says. How your body processes caffeine is partially genetic , she explains. Some people are less efficient at it, which means their 10 am latte could really leave them with caffeine lingering in their system well into the evening.
Even for those who do process caffeine well genetically, relying too much on the stuff causes another vicious cycle when it comes to sleep. At 3 or 4pm, you still have some work to do, but you’re tired because you didn’t sleep the night before, so you have some coffee, which then lingers and makes it harder for you to fall asleep that night.
If you frequently consume caffeine and can’t fall asleep, Dr. Pizzino recommends experimenting with what happens when you greatly reduce it or completely remove it from your diet. This can be hard to execute, though, because she finds a lot of people don’t give it enough of a chance. That’s because if you’re dependent on caffeine at all, removing it will cause your sympathetic nervous system to go into overdrive temporarily, which might make sleep issues worse at first.
But rest assured, if you stick with it for a week, you’ll be able to decipher whether removing caffeine is helpful for you or not. Parsley’s health coaches often work with people to reduce their caffeine intake gradually and monitor symptoms.
Worrying about not being able to fall asleep is also pretty common, and can exacerbate the primary issue. “People who have trouble falling asleep can get into clock watching and tossing and turning, wondering why they haven’t fallen asleep yet,” Dr. Pizzino says. “Now they’ve added that fear on top of whatever was keeping them from falling asleep.”
This is where basic sleep hygiene comes into play: having a dark, quiet, cool room is key, Dr. Pizzino says. These might seem a bit obvious, but they can make a big difference, she adds.
Another core element of sleep hygiene is avoiding blue light before bed, which can block melatonin production , making it tough to fall asleep. “You really need to turn your screens off one to two hours prior to bed,” Dr. Pizzino says.
If you use your phone as your alarm clock, avoid the temptation to scroll right before bed or go old-school with a traditional alarm clock.
There’s also the idea that electromagnetic fields (EMF) emitted by electronics—such as cell phones and wifi routers—may interfere with sleep by impacting brain waves and therefore messing with our ability to fall and stay asleep. This has the potential to interact with our own electrical system, says Dr. Pizzino. Still, the World Health Organization has stated, “current evidence does not confirm the existence of any health consequences from exposure to low level electromagnetic fields,” so more research is needed.
For both of these reasons, Dr. Pizzino recommends leaving your phone charging in another room when you sleep—not on your nightstand.
“As far as your body knows, you just ran away from a tiger,” Dr. Pizzino says. “Are you going to be feeling like going to sleep?” Again, the answer is probably not. That’s why she recommends ideally working out earlier in the day, but definitely not within two hours of bedtime.
“Magnesium is probably the number one nutrient deficiency we see,” Dr. Pizzino says. That’s because it’s not found in the soil much anymore, so it’s hard to get from food. “A lot of people really need magnesium supplementation, so it’s one of the best things to try if you’re having trouble falling asleep.” That’s because it supports brain function, and can help support restful sleep.
Just make sure you’re getting an absorbable form: magnesium glycinate, glucarate, aspartate, or threonate. Avoid magnesium citrate and oxide, Dr. Pizzino says. “Those are good for evacuating your bowels, but they’re not so good for helping you sleep.”
If you find that you frequently can’t fall asleep, consider talking to a healthcare provider. Parsley Health helps members with sleep issues get to the underlying cause and improve their sleep long term.
Julia Malacoff is an Amsterdam-based freelance writer, editor, and certified personal trainer. She covers a wide range of wellness topics including nutrition, fitness, specific health conditions, and the latest scientific research in these field. Julia graduated from Wellesley College and she works with brands like Shape, Cosmopolitan, Fast Company, Precision Nutrition, Equinox, and Aveeno. Outside of work, you can find her walking her dog, trying out a new recipe, or learning Dutch.