Venture Stories

Lullaby: Helping Parents Find More Balance in Their Busy Lives


On June 30, 2023, Yukari Tago, founder of Lullaby, a personalized sleep training service and platform for parents and their newborns, and Dr. Mariko Morita, the platform's supervising physician, spoke at an event held by the Work-X Office, an organization dedicated to improving the office environment at Mitsui & Co. More than 40 Mitsui employees from different departments gathered for the event and participated in roundtable discussions.

Yukari and Dr. Morita discussed Lullaby’s success and shared personal stories and challenges experienced when balancing childcare, work, and homelife. They answered questions and offered several tips and solutions for common problems that parents face.

Key Learnings

  • Sleep training significantly improves sleep for infants and parents
  • Tips on balancing childcare, work, and homelife

The Effectiveness of Sleep Training

Yukari Tago: What I am most proud of is Lullaby's performance of a 99% improvement rate in children’s overall sleep. Our app has a feature that allows users to rate the service, and of the 2,300+ paid napping consultations we provide, 99% of those who have used the service have rated it as good: meaning they have found it to be very successful! Users have shared their success stories and we are very proud of the results. 

Dr. Morita: The problems related to proper bedtime routines are big and are the number one concern for parents in Japan. Those who are troubled feel very strongly about it because they cannot get proper sleep with a newborn. On the other hand, what about children's sleep in Japan? Comparing the total sleep time of children aged 0-3 years old in 17 major countries, Japan ranks last. Data from the Organization for Economic Cooperation and Development (OECD) shows that Japan also ranks last among the 38 OECD member countries in terms of sleep for adult males and females. I feel this is a good indicator showcasing Japan's low awareness of sleep. Marital discord, divorce, postpartum distress, and postpartum depression are some of the effects people face due to their lack of sleep and frustration with their children’s sleeping habits. In Japan, there is currently no common methodology on how to improve a child’s consistent nighttime crying.

The reason I am confident in the 99% improvement rate is because I have evidence. In a survey that analyzed 52 articles on sleep training, 94% of the articles concluded that sleep training was effective in improving nighttime crying, and the results showed that on average, it improved nighttime crying in more than 80% of children. Although the results are solid evidence that sleep training does in fact improve sleep, it is still not widely used in Japan. Even if you go to medical institutions or midwifery centers, they do not provide guidance or proper sleep training techniques. I think that is a problem.

Factors that affect sleep deprivation in adults include the fact that children do not sleep, but also the fact that they will wait for their entire family to return home and eat dinner together instead of utilizing that time for rest. However, the impact of sleep problems on children during infancy, the most difficult time of child-rearing, is still quite significant.

It often takes on average 1-2 hours to put a child fully to sleep. Children often wake up every 1-2 hours to feed throughout the night or wake up between 4:00 to 5:00 a.m. Parents often find themselves stressed with these new circumstances and often experience difficulties to increase their own sleep time.

Studies have shown that the rate of postpartum depression, estimated to be around 10%, has increased to 25% since the coronavirus pandemic. The lack of sleep has had a significant impact on mental health and it’s no surprise that if people can't sleep, they will be irritable and their mental health will suffer.

I want Lullaby to improve nighttime sleep deprivation and help create a society where people are not limited in their choices when it comes to parenting.

Dr. Morita on Weaning, Napping, and Work-Life Balance

Dr. Morita: In the preliminary questionnaire for the Q&A during the event, many participants were concerned about their own sleep, including naps and power naps. We also had many questions about children's sleep and balancing home and work.

To answer how I do it myself, first of all, I use Lullaby to put my own children to sleep. This is the punchline – haha!

However, I think that putting children to bed and getting a good night's sleep is very important for balancing work and family life.

What to do if a child is obsessed with breastfeeding?

We received a question from a person who has a 2 1/2-year-old and said that her child is attached to breastfeeding. Regarding this, I think it is possible to stop breastfeeding at night. If you want to sleep at night, there is no problem to breastfeed only during the day with nocturnal weaning.

However, at that age, I think the child will resist a lot. Be prepared for that, but I think they will get used to it in a week or two. It would be better to first tell the child that he or she will not drink at night, rather than stop during the day as well.

How can someone take an effective nap or power nap?

It is very important that naps for adults are only 20 minutes maximum. If you sleep longer than that, you will go into a deep sleep and have difficulty waking up, or you will feel foggy when you wake up. I recommend setting an alarm or having some caffeine before napping. It takes about 30 minutes after you drink it to take effect, which is said to be just right. If it is too bright for you to sleep, try using an eye mask.

How do you maintain work-life balance?

I recognize that work-life balance may be a matter of priorities. By far, the lowest priority is housework. I think it is important not to do the housework itself. I have three children of my own, so I hardly cook meals anymore. I outsource the preparation of meals.

When I was pregnant with my third child, I physically couldn't cook anymore due to the morning sickness I was experiencing, so I asked someone to come every week and prepare a week's worth of meals for me and my family. To be honest, it doesn't last the full seven days, but on the one or two days that remain, I would cook dried fish, vegetables, rice, and so on.

We also vacuum only once a week. Sorry if it seems dirty! We hire an outside cleaning service to do the cleaning once a week. This alone is a huge relief.

This is a small detail, but serving food from containers is also a hassle in itself, so we put storage containers on the table and make it buffet style. The kids are happy when I tell them they can take whatever they would like. I think it's okay to make it a single-plate meal. It might be another small detail, but I tend to be very sloppy too, like not using chopstick rests.

As for work, I really wanted to do both work and provide childcare, so I chose this line of work partly because I wanted to make child-rearing time useful while I was able to work.

Yukari Tago on Balance and Mental Wellness

How do you ensure proper sleep for your children and for yourself in the midst of balancing work and family?

Yukari: Let me first give you some basic information about me. My son is 6-years-old now. My parents live in Tokyo, 15 minutes by bicycle from our home. My husband's parents live in Shizuoka [over 100 miles from Tokyo].

Typically, I drop my child off at around 8:30 a.m. and pick him up at 6:30 p.m., while my working hours are from 9 a.m. to 6 p.m. I have free time at night two-and-half days a week. My husband and I take turns doing this schedule, and we both make sure to have two-and-a-half days of free time each week at night. During that time, I try to spend my free time doing the work I want to finish, meeting people, getting massages, physical therapy, saunas, etc. to refresh myself and take care of my health. By doing this, I maintain my mental health and consciously try to keep myself in a state where I can be happy.

How do you maintain your mental health?

Mental control is the biggest thing I have learned since I was transferred from Mitsui & Co. to Moon Creative Lab and started working on Lullaby. I always feel like someone is evaluating my work, but that is why I try to maintain my mental health. Of course, there are times when things don't go well, but I think that if my mental health breaks down, my work efficiency will drop very badly.

As for work, most of the people working for Lullaby are outsourced, except for me, so the content and volume of outsourcing are clearly defined, and I feel that makes it easy to work efficiently.

How do you make time for yourself?

I thought it might not be very helpful to know how to generate time, as there are many external factors, but I feel that Moon's flexible working style (core hours are from 10:00 a.m. to 2 p.m.) makes it very easy to work.

The scale of the business is still small and I have authority to make most of the decisions. I make decisions on what to do, which I think is one of the main reasons why I can work quickly. Also, since it is a domestic business, there are no overseas business trips.

Also, many mothers have a lot of spare time. In order to make the best use of our spare time as mothers, we are gradually preparing useful tools on our app all while consulting with our members. Almost all of our staff members are mothers, and since we are all sleep consultants, our children are all asleep around 9 p.m., allowing us time to catch up and discuss Lullaby. We all have a shared love for the business, so we think about it all the time, 24 hours a day, and I think that is one aspect that allows us to make a lot of decisions quickly.

At home, my son is fast asleep by 9:00 p.m., which is a big advantage. Perhaps the most important thing for me is that he’s in good health because of his sleeping pattern. He has attended various preschools, kindergartens, and afterschool programs, and he has received perfect attendance awards to all of them. It may not all be due to sleep, but I still believe it is related to the fact that lack of sleep often relates to getting sick more often.

You might be familiar with the book, The 100-Year Life: Living and Working in an Age of Longevity, and I feel that book is the root of my way of thinking. Life is long, so it is a question of what to prioritize now. I'm not able to save much now, but I've decided that it's one stage in the long run, and I'm outsourcing as much housework as possible, and even if I have to live in a smaller house, my first priority is to generate time for travel distance, work, and family.

I can relate to Dr. Morita as I also use a make-and-prepare service and have found it to be very helpful.


Yukari Tago, founder of Lullaby, is a mother to her son and experienced child rearing years in the United States. While raising her son, she struggled with his frequent nighttime crying and, after practicing a sleep training program she learned while in the U.S., she experienced a dramatic improvement. Using her experience in startup investment in the EdTech industry, she commercialized her idea to improve nighttime crying. She joined Moon Creative Lab from a career at Mitsui to start Lullaby.


image3.jpgDr. Mariko Morita is a mother of three and supervising physician for Lullaby. She worked as an anesthesiologist, but started researching pediatric sleep after facing nighttime crying with her first child. She currently provides counseling as a sleep medicine doctor, trains sleep consultants, and publishes books on pediatric sleep.

Lullaby’s founder and doctor share stories and challenges of balancing childcare, work, and homelife, and offer several tips and solutions for common problems that parents face.



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