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Infant Sleeping After Vaccine: Should You Worry?

In this article, we will take a close look at the effects of vaccination on infant sleep. We will discuss how immunization can lead to increased sleep duration in some infants, the potential side effects that may temporarily affect sleep, and the safety of allowing an infant to sleep after receiving a vaccine.

Jakub Gwiazdecki

Author - Jakub Gwiazdecki

Fifth year medical student at the Medical Faculty of Comenius University in Bratislava.

Jakub used MediSearch to find sources for this blog.
MediSearch gives instant answers to medical questions based on 30 million scientific articles.

Should you worry if your child sleeps after a vaccine?

You should not be worried or surprised when your child sleeps longer after a vaccine. Infants can sleep longer during the first 24 hours after the vaccination [1].

In case your infant suffers from low-grade fever, its sleep duration can change too. Infants with fever as a side effect after vaccination can sleep long [1].

However, not all infants will sleep longer after the vaccine. Some of them will not show any changes [2].

Why do infants sleep after vaccine?

The primary reason why infants sleep after a vaccine is the immunological reaction of their body. The infant's autoimmune reaction uses a lot of energy. This leads to a need for longer sleep [3].

Interestingly, infants that receive their vaccine in the afternoon or have a fever after the vaccine usually sleep longer [1, 4]. Vaccination triggers an immune response, which can lead to increased fatigue and sleepiness. This effect may be more pronounced in the afternoon due to the natural dip in alertness that occurs later in the day.

How do vaccines work?

The mechanism of vaccine action is similar in all types of active immunizations. Vaccines contain an attenuated bacteria or virus or a part of them. However, they are not pathogenic. That means they do not cause any diseases.

After the vaccine injection, the immunological system of the body activates. It recognizes the foreign genes and starts the reaction that leads to antibody production.

The antibodies produced in the reaction after the vaccine are saved for later in the memory cells in the body.

When the body comes in contact with the same bacteria or virus again, the antibodies will be released to combat the attacker. It minimizes the time and symptoms of serious infections. Some people will not even notice that they are ill, while others will have only weak symptoms. Also, vaccines lower the risks of complications and mortality.

The vaccination is crucial for an effective and fast answer to a future infection. However, the process costs the infant a lot of energy. Therefore, the infant may need to sleep longer after the vaccination.

Is it safe for the infant to sleep after vaccine?

Yes, it is completely safe for an infant to sleep after a vaccine. The infant may need sleep to speed up the immunological response to the vaccine.

Also, thanks to the sleep, the infant will feel better after the vaccine.

However, preterm infants need special attention. They are at increased risk of stopping to breathe or having a slower heart rate in the first three days after the vaccination [5]. .

In case your infant is preterm born and the doctor is not aware of this fact, you need to remind the physician of this fact.

What types of vaccines should be given to an infant?

According to the CDC, the first recommended vaccine is against hepatitis B. Normally, the first shot of this vaccine is given at birth in newborns. The second shot should follow two months later.

Vaccination against Hepatitis B is crucial. When a not vaccinated infant gets hepatitis B, in 9 out of 10 cases the infection will be chronic. Additionally, around a quarter of infants with hepatitis B will die later in life due to chronic liver disease [6].

Around the second month of age, the infant should receive vaccinations against diphtheria, tetanus, pertussis, pneumococcus, rotavirus, poliovirus, and Haemophilus influenzae type b. All these should be repeated two and four months after the initial vaccine [7].

The only exception is the rotavirus vaccine. This one should be given according to the recommendations of the brand [7].

However, the vaccination plan for the infants depends on their health. To develop a fitting vaccine calendar for your child you should visit a pediatrician.

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