Baby that is too tired

Overtired Baby: What Happens When Your Baby Becomes Too Tired

Overtired Baby: What Happens When Your Baby Becomes Too Tired

Sleep, like food, is a basic human need. The distress babies experience due to lack of sleep varies in intensity according to the level of sleep debt. Read more about the reasons babies become overtired and how they behave when overtired.

What it means to become overtired

Overtiredness lies somewhere between tiredness and exhaustion.

Tiredness     →         Overtiredness          →         Exhaustion

Sleep is a basic human requirement that is as important to our physical wellbeing as nutrition. Lack of sleep is a source of stress to our body, affecting us physically and emotionally. Overtiredness means your body has gone beyond being ready to sleep. It involves a state of physical fatigue that disrupts homeostasis (a state of balance within the body) and activates your stress-response system. 

Once overtired, stress hormones such as cortisol and adrenaline flood your bloodstream. These are often referred to as ‘fight or flight’ hormones because they increase your state of awareness, speed up your heart rate, raise your blood pressure and cause tension to build up in your muscles. Despite being physically fatigued, your mind is alert. You feel keyed up or agitated, ready to take flight or fight.

How to recognize an overtired baby

Babies also become distressed owing to over tiredness, but unlike adults who become lethargic when overtired, babies and young children become hyperactive. A sleep-deprived baby:

  • receives well below the average amount of sleep for her age (see How much sleep a baby needs);
  • appears to fight going to sleep;
  • is easily woken by even the slightest noise, eg, doors opening, talking;
  • sleeps very little during the day most days – day-time naps are typically very brief, eg, 20–30 minutes;
  • appears uncomfortable during feeds or periodically refuses to feed during the day, while feeding well during the night;
  • wakes excessively or sleeps unusually long periods during the night without waking for feeds;
  • is difficult to get to smile or engage in eye contact;
  • often has a worried expression;
  • is generally more content in the mornings than in the afternoons;
  • finds it increasingly more difficult to fall asleep as the day progresses;
  • cries often, ranging from whining to vigorous, inconsolable cries;
  • has a short attention span;
  • requires constant attention from you when she’s awake;
  • wants to be held continuously, fusses in your arms, but cries whenever you put her down;
  • resists going into her pram, high chair, crib or car seat;
  • likes to be jiggled or rocked endlessly;
  • startles often;
  • experiences extreme separation anxiety;
  • displays frequent physical or crying outbursts;
  • has an insatiable appetite (these babies are often described as ‘hungry babies’);
  • may feed briefly or fall asleep before the feed is completed.

Of course, all babies behave like this from time to time. It is the degree and frequency to which a baby displays these behaviors, plus the fact that she’s getting much less than average sleep for her age, that points to sleep deprivation. 

Catch-up sleep

Chronically sleep-deprived babies will typically have 'catch-up' sleep from time to time. An overtired baby might crash at night, sleeping usually long periods without demanding feedings owing to physical exhaustion that occurs as a result of not receiving enough sleep during the day. Or she might occasionally have catch-up sleep during the day instead. She might sleep for unusually long periods during the day, after days of not getting enough sleep. She could sleep for 3 or 4 hours in one nap or she might have a number of long naps. This is not something she decides to do; it just happens, to restore the balance. 

Once she has caught up on sleep – which could take a day or two depending on how sleep deprived she had become – she will appear much happier (because her body’s natural balance has been restored). She feeds better, settles to sleep quicker and is less tense and demanding of your attention. However, if the cause of her sleep deprivation remains unresolved, relief is usually only temporary.

Catch-up days are often a source of confusion. They provide stressed, sleep-deprived parents with much-needed relief. But they can also trick you into thinking that the situation is finally resolving itself or that whatever new strategy you might be trying, for instance a new settling method, dietary change or medication, is working. If it is just a catch-up day, then within a day or two you’re likely to find your baby’s behavior relapses as her sleep debt builds once again.

Problems linked to infant sleep deprivation

Sleep deprivation alone is a major source of distress to babies, and parents. But sleep deprivation can also be the underlying cause of other problems that then add to the baby's distress. For example: 

Overstimulation in babies

Overstimulation occurs when a baby’s nervous system becomes overloaded by too much sensory stimulation. Baby becomes overwhelmed by too much happening to him or around him. Too much stimulation is stressful for a baby who is powerless to remove himself from the situation.

When we’re tired, we want peace and quiet. This is because we don’t enjoy or handle sensory stimulation very well when tired. A baby is no different. If a baby is not getting enough sleep, she’s going to be sensitive to any sort of sensory stimulation, like bright lights, loud or sudden noises, getting dressed or undressed, having a bath or massage, or being jiggled or patted. If she’s is a newborn, she’s even more vulnerable to overstimulation owing to immaturity of her nervous system. Overtired/overstimulated newborns can continue to cry, despite parents’ best efforts to soothe them, for what can feel like or literally be hours on end.

Gastrointestinal discomfort

When a baby wakes prematurely from sleep still tired, or fusses or cries for unknown reasons, hunger is typically the first thing blamed. If we believe baby is hungry will understandably try to give her more food. This could involve breastfeeding more often; offering both breasts at each feeding; offering infant formula in addition to breastfeeds; increasing the frequency of bottle-feeds; increasing the volume of formula given at each feeding. Newborn babies (birth to 3 months) have limited ability to regulate their dietary intake because of the presence of their sucking reflex, and this makes them vulnerable to overfeeding if parents are not careful. Certain feeding practices, in particular those that aim to get baby to take more milk, can cause babies to suffer from gastrointestinal discomfort/pain owing to lactose overload 

If the above mentioned strategies fail to improve baby’s quality of sleep - and they will fail if the cause of baby’s sleep disturbance is unrelated to hunger, which in most cases it is - you might be advised to try adding rice cereal to baby’s bottle and/or start giving baby solid foods at a very early age (before 4 months) in a bid to get her to sleep better. Each of these strategies have the potential to have a negative impact on the nutritional balance of a baby’s diet.  

So, what begins as an infant sleep problem - due to reasons described below - now becomes even more complicated if feeding practises cause gastrointestinal discomfort/pain - which then makes it even harder for the baby to sleep.


Some chronically sleep-deprived babies struggle to gain sufficient weight. A sleep-deprived baby can become too exhausted to feed effectively and therefore miss out on the nourishment she needs for healthy growth. Sleep-deprived babies often sleep for unusually long periods during the night, too exhausted to wake for night-time feeds.

A sleep-deprived breastfed baby might feed ineffectively, not draining the mother’s breast or stimulate her supply and thus her mother's milk supply can drop in response, which then means less milk will be available to the baby. In most cases of poor growth, I find a breastfed baby’s fatigue from not getting enough sleep to be a major contributor to low supply rather than low supply being the cause of a baby's broken sleep, at least in the early stages. Once milk supply has dropped this can further disrupt the baby's sleep.

Fussy feeding behavior

When we are physically fatigued, it affects our coordination and we can become impatient and easily frustrated. Babies can have the same reaction when they’re tired. While they may or may not experience poor growth, both breastfed and bottle-fed babies can display fussy feeding behavior owing to lack of sleep. (See reasons for fussy feeding behaviour.)

Developmental delay

All of us have difficulty learning new skills and retaining new information when we’re tired. And we may not have enough energy for physical activity when we’re fatigued. So, it is possible that chronic sleep deprivation could delay a baby’s development. This doesn’t mean the baby won’t catch up; simply that she might not learn new skills as quickly as she would if she was well rested.

Parental distress

Parental stress as a result of caring for a distressed, sleep-deprived baby day after day and night after night can be as much a problem for a baby as it is for parents because babies are dependent on others for their care. Under the influence of 'fight or flight' stress hormones, we have a natural tendency to act out aggressively or retreat. It is not surprising that babies and children are at increased risk of receiving unresponsive or hostile care when parents are stressed out or sleep-deprived. Sadly, this can happen.

Not all stressed parents provide unresponsive or hostile care, but it requires a far greater effort to provide responsive nurturing care for a baby when exhausted than when you’re well rested. Even the most gentle, placid parents have limits when their bodies are under constant stress. It is important that your baby gets the sleep she needs to reduce her levels of distress. It’s equally important that you, her parent or caregiver, also receive sufficient sleep.


Distressed, overtired babies, some of whom suffer gastrointestinal symptoms due to lactose overload (owing to errors in feeding management as a result of mistaken assumptions about the cause of baby's wakefulness and consequent sleep deprivation) are commonly misdiagnosed with medical conditions like colic, reflux, lactose intolerance, milk protein allergy or intolerance, that they do not have.

Needless medications (anti-colic medications and antacid medications) and dietary changes such as switching to a lactose-free formula (soy and hypoallergenic formulas are lactose-free) often do little if anything to resolve a baby’s distress, and may actually add to baby's distress at the time and/or cause problems for baby further down the track.

How to help your baby to sleep

Unfortunately, getting enough sleep is not a simple process for babies or young children owing to their reliance on parents to…

  • Recognize early signs of tiredness. Later signs might indicate a baby is already overtired. Once overtired a baby will find it difficult to fall asleep. (See Infant tired signs.)
  • Provide an opportunity to sleep in an environment that is conducive to sleeping. If the environment is too stimulating - bright lights, noise etc. - the baby might remain awake despite her readiness to sleep and risks becoming overtired... and then find it difficult to fall asleep.
  • Provide baby’s sleep associations (the conditions, props as activities that baby has learned to psychologically associate with sleeping) at the time she's ready to sleep. Without the presence of her sleep associations a baby might remain awake despite her readiness to sleep and thus the risk of her reaching the point of over-tiredness increases with every minute her sleep is delayed.
  • Ensure sleep associations remain consistent throughout baby’s entire sleep. Once a baby learns to rely on certain sleep associations to fall asleep this usually means they rely on the same sleep associations to remain asleep. The absence of baby’s sleep associations during light sleep increases the risk of her waking too soon from sleep, and as a result increases the risk her becoming overtired. 

What you can do to help your tired baby

Babies are not born 'good' or 'bad' sleepers. They sleep well or sleep poorly depending on the presence or absence of their sleep associations.  

Most parents are unaware of how their actions influence their baby's sleep…. for better or worse. As your baby's parent or caregiver, you exert a strong influence over her sleep by the decisions you make or don't make when she is tired and by your infant settling practices. You have the power to improve the quality and quantity of her sleep increasing your awareness of her behavioral cues and/or by making changes to the way in which you settle her to sleep. Change for change sake will not necessarily be helpful. Any change needs to be directed in a way that will support her to remain asleep for as long as her little body requires. 

This article is a small snippet of the helpful information you will find in my infant sleep book entitled ‘Your Sleepless Baby: The Rescue Guide’. Inside 'Your Sleepless Baby' you will find physical, developmental and behavioral reasons for infant sleeping problems. Explained is what babies need from parents to sleep well and ways in which parents influence their baby's sleep. You will also find a range of options on ways to promote a baby’s sleep to suit different ages and parenting styles.