The True Nature of "Feeling Unfulfilled"—True Happiness Created by Oxytocin and Sleep

"My work is going well. My children are healthy. I have a family. Yet, for some reason, there is a hollow void in my chest."

Have you ever felt that way?

It is not that you are lacking anything material. It is not that someone has done something unpleasant to you. But the feeling of "somehow unfulfilled" or "something is missing" drifts faintly at the bottom of your daily life.

This is not about having a weak will or a lack of gratitude. It is a matter of neurotransmitters. To be precise, it is the depletion of "oxytocin."

And the secretion of oxytocin is deeply connected to sleep.

Today, I will explain the true nature of the feeling of "being unfulfilled" through neuroscience, and discuss how to regain a sense of true happiness by regulating your sleep.Everyone is the manager of their own body. Happiness can also be managed as one of your management decisions. I will share this from that perspective.

◎ "Unfulfillment" is not a problem of the heart, but a problem of neurotransmitters

☆ The four neurotransmitters that create happiness—why only oxytocin is different

There are four well-known neurotransmitters related to happiness: dopamine, serotonin, endorphins, and oxytocin.

Dopamine is the happiness of "achievement and reward." It is released when you achieve a goal, get something you want, or do something you want to do.

Serotonin is the happiness of "stability and calmness." It creates a foundation of gentle, calm satisfaction and a steady mind.

Endorphins are the happiness of "pleasure and release." This is the euphoric happiness secreted through exercise or laughter.

And oxytocin has a different nature. Oxytocin is the happiness of "connection, love, and security." While the other three are "happiness completed within oneself," only oxytocin is "happiness born from a connection with someone else."

When you achieve results and dopamine is released, or when serotonin is stable, but you still feel "somehow unfulfilled"—that may be a sign that you are lacking oxytocin. Humans are structured in such a way that they cannot be truly fulfilled without connection.

☆ What is oxytocin—the hormone that creates "connection" and "security"

Oxytocin became widely known after Swedish neuroscientist Dr. Kerstin Uvnäs-Moberg (2003) systematically studied it as the "love hormone."

Initially known as the "childbirth and breastfeeding hormone," it is now understood as a substance involved in the overall "happiness of connection" for both men and women.

When is oxytocin secreted? During physical contact (hugging, shaking hands, touching), conversations with trusted people, time spent laughing together, playing with children, interacting with pets, and moments of feeling gratitude—these are "experiences of warm connection."

When oxytocin is secreted, the following things happen: anxiety is eased. Your heartbeat calms down. Blood pressure drops. Trust in others increases. A sense of security that "it is okay to be here" is born. And an indescribable feeling of "being fulfilled" arrives.

Furthermore, oxytocin has been reported to have effects such as boosting immune function, alleviating pain, and aiding digestion (Uvnäs-Moberg, 2003). The happiness of "connection" is directly linked not only to mental well-being but also to the health of the entire body.

This is precisely the feeling that lies on the opposite side of "feeling unfulfilled."

☆ The structure where modern busyness causes chronic oxytocin depletion

When you are running a business while raising children, "connection time" is easily cut short.

Even when you are facing your children, your mind is thinking about the next task. Even when you are with your partner, you are looking at your smartphone. Even when you are talking to someone, you have the feeling that you "need to finish this quickly."

Physically, you are "together," but your hearts are not connected. This is the typical form of modern "oxytocin depletion."

Furthermore, when chronic stress and sleep deprivation overlap, cortisol (the stress hormone) remains high. And cortisol and oxytocin have an antagonistic relationship—when one goes up, the other tends to go down.

A state of being busy and highly stressed makes it difficult to secrete oxytocin. One of the true natures of "everything is going well, but I feel unfulfilled" lies here.

◎ The mechanism by which sleep deprivation destroys oxytocin

☆ Oxytocin is secreted and replenished during sleep

It is known that oxytocin secretion is promoted from the hypothalamus in the brain during sleep. Especially during the deep sleep (non-REM sleep) stage, the rhythm of oxytocin secretion is regulated.

In other words, on the morning after you have slept well, you can start the day with oxytocin "replenished." That is why, on a morning after a good night's sleep, you can naturally smile when you see your child's face. Your words to your partner become softer. You can honestly say "thank you" to someone's kindness.

Conversely, on the morning after sleep deprivation, you start in a state where oxytocin is depleted. Even if your child does the same thing, you feel they are "noisier" than usual. People's words sound cold. Dissatisfaction comes before gratitude. This is not a problem of personality or a problem of love. It is simply that oxytocin has not been replenished.

On days when you think, "I feel irritated at everyone today for some reason" or "there are moments when my child doesn't look cute," please look back at the duration and quality of your sleep the previous night. The answer is often there.

☆ Cortisol and oxytocin are antagonistic—stress steals love

When sleep deprivation continues, cortisol secretion increases chronically. Cortisol is a hormone that creates a "fight or flight" state of tension. It puts the brain and body into "survival mode."

Research by Heinrichs et al. (2003) has shown that the effects of oxytocin are suppressed when cortisol levels are high. In other words, when stress is high, the circuit that feels "connection" becomes dull.

In survival mode, survival takes priority over connection. You feel like you "can't right now" when your child tries to talk to you. A partner's comment sounds aggressive. You cannot accept kindness from others at face value. These are all signs of excess cortisol and a lack of oxytocin.

Regulating your sleep to normalize cortisol is the first step toward restoring the function of oxytocin.

☆ Why poor sleep makes it harder to feel "connected" the next morning

When sleep quality is low, the parts of the brain involved in "social cognition"—especially the coordination between the prefrontal cortex and the amygdala—do not function properly.

Research by Dr. Walker (Walker, 2017) reports that when experiments are conducted on reading others' facial expressions while sleep-deprived, there is an increase in cases where neutral or smiling expressions are misidentified as "threats or hostility."

When sleep is light, the brain is more likely to perceive the surroundings as a "place to be vigilant" rather than a "safe place." This further suppresses the secretion of oxytocin.

"Somehow, my conversations with people feel awkward today," or "I feel like my heart is elsewhere even though I'm talking to someone." Did you get enough sleep the night before such days? The answer may be hidden there.

◎ The structure of why parenting business owners fall into feeling "unfulfilled"

☆ Nights when you are with your child but somehow cannot connect

You are checking emails on your smartphone while putting your child to bed. Your child asks, "Hey, are you listening?" You answer, "I'm listening," while unable to take your eyes off the screen.

The physical distance from your child is zero. But the emotional distance is far.

On nights like these, almost no oxytocin is secreted. Oxytocin is only released through physical touch or conversation when your "consciousness is present there." As long as your body is together but your consciousness is elsewhere, your brain does not feel a connection.

For parents, children are the best coaches and mentors.Children sensitively sense whether "Dad (or Mom) is here right now" or "they are somewhere else." A child's "Hey, are you listening?" is also a question directed at a parent who is lacking oxytocin.

Spend even 10 minutes with your child putting your smartphone away to create "time to truly face each other." Those 10 minutes generate oxytocin that cannot be measured by quantity.

☆ The reason why you feel empty despite achieving results

You achieved your goal. Sales went up. Someone praised you. But the next morning, a feeling of "So what?" remains.

The sense of achievement from dopamine is short-lived. Without the next goal, it drops sharply. Even if you keep chasing "greater results," the underlying feeling of being "unfulfilled" is never resolved.

This is a sign that you are lacking oxytocin. Oxytocin is only secreted when you frame your achievements in the context of "rejoicing with someone," "being thanked by someone," or "doing something for someone else."

Celebrating business achievements with others. Seeing a child's smile as the meaning of your success. Being present for the moment a staff member grows. Such "achievement within connection" creates true happiness.

Success shared with others brings longer-lasting happiness than "success achieved alone." This is not just a matter of emotion, but stems from the fundamental differences between dopamine and oxytocin.

☆ The more you put off "enjoying" life, the more your oxytocin levels dwindle

Enjoying yourself is a way of healing yourself.

When people are enjoying themselves, they are in the "here and now." When laughing, when immersed in something, when having a lively conversation—your consciousness is not on the past or future, but on the moment right in front of you. That is when oxytocin is most easily secreted.

Conversely, if you continue in a state of "I'll enjoy myself later," "Work comes first right now," or "This is no time for play," you lose more and more opportunities to replenish your oxytocin.

A carefree way of life—the attitude of pursuing things that make you happy and joyful—is not about having an "optimistic personality," but a scientifically rational choice for the brain to consciously replenish oxytocin. Do not neglect enjoying yourself. That is one of the most direct ways to keep that "feeling of being unfulfilled" at bay.

◎ Reclaiming Oxytocin—Habits of Sleep and "Connection"

☆ Physical contact and falling asleep—Putting children to bed as an oxytocin recharge

Putting children to bed is not a "tedious chore" but an "oxytocin recharge time."

Hugging your child, stroking their back, holding hands—this physical contact triggers the secretion of oxytocin. Put down your smartphone, feel your child's body heat, and lie down together. Try asking, "What was good about today?" Close your eyes while listening to your child's breathing.

This time is not just for the child; it is also a time for the parent to replenish their own oxytocin. Instead of thinking, "I hope this ends soon" while putting them to bed, simply thinking, "This time is creating oxytocin," changes the quality of the experience.

Playing, being emotionally close, and guiding—the nighttime hours with your child are a time for parenting, but also a time for parents to fulfill themselves.

☆ Gratitude and a sense of security—"Warm thoughts" before sleep promote secretion

Oxytocin is also secreted from "remembered connections." It is known that even without actual physical contact with someone, vividly imagining warm connections can promote the secretion of oxytocin (Domes et al., 2007).

Before you go to sleep, try asking yourself these questions.

"Was there a moment today when I felt someone's warmth?"
"Was there anything I was able to do for someone today?"
"Was there a moment today when I made eye contact with my child and we smiled?"

This is an extension of a "gratitude journal," but the point is to focus on the "warmth of connection" rather than just "gratitude." Vividly imagining that moment—feeling the sensation of your chest warming up in your body—prompts the secretion of oxytocin before you fall asleep.

When you fall asleep with warm thoughts, it promotes the replenishment of oxytocin during sleep and increases your "connection sensitivity" the next morning. The habit of ending your day not with "Today was good," but with the perspective of "Today, I connected with someone"—as this accumulates, the baseline of your daily "sense of fulfillment" will rise.

☆ Improving the quality of deep sleep creates the next day's "sense of connection"

I have shared practices for improving the quality of deep sleep in previous articles, but I will organize them again from the perspective of oxytocin.

Put your smartphone away 90 minutes before sleep (blue light hinders melatonin secretion and makes deep sleep shallower). Refrain from alcohol (alcohol may seem to help you fall asleep, but it significantly hinders deep sleep). Keep your bedroom temperature between 18 and 20 degrees Celsius (a drop in body temperature is a trigger for deep sleep).

And the most important thing is to "fall asleep with a warm heart." When you fall asleep with low cortisol and activated oxytocin, it becomes easier to enter deep sleep.

Sleep is a skill and a tool. You can start "designing your sleep" to replenish oxytocin starting tonight.

◎ True happiness comes from the "inside," not the "outside"

☆ Goal achievement and happiness—the true nature of what lies beyond the finish line

You keep running, thinking, "Once I achieve that goal, I will be fulfilled." You achieve it. You were happy. But three days later, you are back to "feeling unfulfilled."

This is a characteristic of dopamine. Dopamine is released at the "moment of achievement," but it is quickly reset, and you begin to seek the next goal.

But oxytocin is different.The happiness brought by oxytocin lasts gradually and for a long time. The feeling of being deeply connected to someone, the feeling of being trusted, the feeling of being loved—these are calm and lasting forms of happiness that differ from the instantaneous joy of achieving a goal.

The goal comes first! The method comes later!—When setting a goal, imagine not only "what to achieve" but also "in what kind of connection you will realize it" first.With that perspective, the possibility that a "fulfilled self" will be waiting beyond the achievement increases.

☆ Time flows from the future—designing your fulfilled self in advance

Time flows from the future.

A "fulfilled self" is not born after achieving something, but begins with the design of tonight's sleep.

Ask yourself before you sleep: "Who will I be a year from now, and in what kind of connections will I be living?" "Can I fall asleep tonight feeling gratitude or love for someone?" By falling asleep with these questions in mind, oxytocin is promoted, your sensitivity to connection increases the next morning, and you move closer to a "sense of fulfillment."

Place your "fulfilled self" as a future goal first. Design how you sleep tonight to move toward that. That is a way of living that "welcomes" happiness rather than "chasing" it.

☆ The Relationship Between an "Okiraku" (Carefree/Happy-go-lucky) Lifestyle and Oxytocin

Chasing things that make you happy and joyful—an "Okiraku" way of living. This is not just a "positive attitude," but a scientifically sound way of living to continuously replenish oxytocin.

When people feel happy, they are open. When the heart is open, it becomes easier to feel connected. When you feel connected, oxytocin is released. When oxytocin is released, it becomes easier to notice even more happy and joyful things.

This is not about "trying hard with positive thinking." It is about a mechanism where the brain's reward system and love system work together to create a virtuous cycle.

"Enjoying things is healing yourself"—this phrase hits the essence accurately, even from the perspective of the brain chemical oxytocin. Do not neglect to enjoy things. That is the most direct path to keeping "feeling unfulfilled" at bay and moving closer to true happiness.

Summary: Tonight's Sleep Creates Tomorrow's "Sense of Fulfillment"

Let's organize what I have shared today.

・The true nature of "feeling unfulfilled" is a depletion of oxytocin (the connection hormone)
・Oxytocin is replenished during sleep. Sleep deprivation chronically lowers oxytocin
・Cortisol (the stress hormone) and oxytocin are antagonistic. Improving sleep lowers cortisol and restores oxytocin
・Physical touch with children, warm conversations, and thoughts of gratitude trigger the secretion of oxytocin
・The sense of achievement from dopamine is short-lived. The sense of connection from oxytocin is long-lasting
・Do not neglect to enjoy things. That is the most direct way to continuously replenish oxytocin

Sleep is a skill and a tool. Please try designing your sleep starting tonight to replenish your oxytocin.

Time flows from the future. Your "fulfilled self" has already begun within tonight's sleep.

■ Main References

・Uvnäs-Moberg, K. (2003). The Oxytocin Factor: Tapping the Hormone of Calm, Love, and Healing. Da Capo Press.
・Carter, C. S. (1998). Neuroendocrine perspectives on social attachment and love. Psychoneuroendocrinology, 23(8), 779-818.
・Heinrichs, M., et al. (2003). Social support and oxytocin interact to suppress cortisol and subjective responses to psychosocial stress. Biological Psychiatry, 54(12), 1389-1398.
・Domes, G., et al. (2007). Oxytocin improves mind-reading in humans. Biological Psychiatry, 61(6), 731-733.
・Walker, M. (2017). Why We Sleep: Unlocking the Power of Sleep and Dreams. Scribner.