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Interrupted sleep: What are the consequences, and the way can we cope?

July 12, 2023
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No, parents, you aren’t crazy. Interrupted sleep can tank your mood and impair your functioning — above and beyond the harm caused by getting less sleep overall. But why do sleep disruptions have these effects? Research tells us why we should take the problem seriously, and it offers helpful insights. The important thing is to protect your brain’s ability to get enough slow-wave sleep. If you can lock down at least one, 3-4 session of uninterrupted sleep — and take other measures to improve sleep quality — you can improve your health and well-being.

Poor sleep is a major complaint for parents. How bad is it?

If you have a child who keeps waking you up at night, you don’t need me to tell you how you feel. You’re exhausted, strung-out, or lost in a zombie-like haze.

The first weeks of infant care can be especially tough. Newborns need frequent feedings, and their sleep patterns are out-of-sync with the natural rhythms of day and night.

As babies mature, they develop more mature sleep patterns, which is helpful to us. But night wakings continue for months. And even when children are older, they may experience sleep disorders that disrupts our sleep routines. According to a study conducted in Germany, parents may not re-establish satisfactory sleep patterns until several years after the birth of their first child (Richter et al 2019).

It’s one of more obvious burdens that parents struggle with. Yet when researchers have tried to quantify it — by measuring sleep in new parents — they have sometimes reported numbers that seem too good to be true. The sleep loss that (on paper) sounds relatively mild.

How much sleep do new parents typically get?

Researchers may come up with somewhat different estimates depending on the methods they use. They could simply ask parents to provide their own estimates (e.g., “how much sleep are you getting these days?”), which is the approach taken by many non-scholarly, popular surveys. But this isn’t as accurate as either (1) asking parents to keep a detailed sleep diary for several days in a row, or (2) asking parents to wear movement-detecting devices (wrist actigraphs) that measure sleep-time in a relatively objective way. In some studies, researchers do both.

What do these more accurate methods reveal? Numbers that have surprised me. For example, during the first 8 weeks after childbirth, mothers are often reported as getting (on average) at least 7 hours of sleep (e.g., Insana et al 2011; Park et al 2013; Filtness et al 2014; Insana and Montgomery-Downs 2013). And when researchers have tracked changes in sleep duration from pregnancy to new parenthood, they’ve noted reductions that are important, but not super-dramatic.

In a recent meta-analysis of some of the best studies available, the average amount of sleep loss experienced by new parents each night — throughout the first 16 weeks postpartum — was estimated at just 43 minutes (Parsons et al 2023).

Of course, these estimates come with a lot of cautions. During the later months of pregnancy, many women experience sleep problems (Sedov et al 2018), which can include short sleep duration (e.g., Reid et al 2017). So if new mothers are losing an average of 43 minutes of sleep after the baby comes, that may represent an increase over and above whatever sleep deficit they were already coping with.

Moreover, any talk of averages alone can’t help us appreciate the range of variation. Many folks are coping with higher-than-average levels of sleep deprivation.

Still, my mind boggles when I read results like these. How do we reconcile such reports with our everyday experiences? The research makes it sound like baby-care isn’t really such a sleep-sapping proposition after all. Not for most people. And that can’t be right. But here’s the thing…

Total sleep time isn’t the only aspect of sleep that goes haywire when you become a parent.

How often are you being awakened each night, and how disruptive are these wakings? How much time are you spending awake after initially falling asleep (what investigators term “Wake After Sleep Onset”, or WASO)?

When researchers focus on sleep interruptions, rather than total sleep time, they get a very different picture of how sleep changes after a baby. For instance, that 43 minute average sleep deficit for parents during the first 16 weeks postpartum? It represents a reduction of sleep time by approximately 10%. By contrast, researchers found that average WASO increased by 47% during the same period (Parsons et al 2023).

So it’s likely that interrupted sleep has something to do with the strung-out, zombie-like feelings that we experience during postpartum life. But why should this be?

Understanding sleep cycles: Why interrupted sleep causes trouble

exhausted father holding infant

If something keeps waking you up at night, it’s pretty obvious that you’re at higher risk for getting less sleep overall. You might have trouble falling back to sleep, so you aren’t able to take full advantage of the time you have left. In this way, interrupted sleep can lead to restricted sleep — less total sleep time.

But there is another way in which fragmented sleep can cause problems, and to understand it, you need to think about human sleep cycles.

When we’re allowed to doze normally, sleep unfolds in a series of stages, beginning with two stages of light sleep (NREM1 and NREM2); continuing with a stage that emphasizes, deep, slow-wave sleep (NREM3); and ending with rapid eye movement sleep (REM).

A single cycle takes 90-110 minutes to complete, on average, at which point we either awaken, or continue with another cycle. And adults usually complete 4-6 cycles each night. But the crucial point is this: All sleep stages are NOT equally restorative or crucial for our health.

In experiments where people have been deprived of all sleep, it appears that NREM3 is the stage that the brain misses the most. When study volunteers are finally permitted to snooze, their brains prioritize slow-wave sleep. Moreover, the extent to which people bounce back after sleep deprivation — the degree to which they become alert, focused, and competent again — depends on the intensity of their deep, “recovery” sleep (McNamara 2019).

In fact, researchers have been able to minimize the cognitive side effects of sleep deprivation (such as attention lapses, and working memory performance) by artificially enhancing slow-wave activity during sleep recovery (Zhang and Gruber 2019). In addition, there is strong evidence that NREM3 helps us maintain a strong, healthy immune system, and that deep, slow-wave sleep promotes growth, repair, learning, hormonal regulation, and the removal of hazardous protein clumps (amyloid plaques) that build up in the brain when we’re awake (McNamara 2019; Winer et al 2020).

So slow-wave sleep plays a crucial role in your well-being

What happens if someone wakens you when your brain is in NREM3? Or awakens you even earlier in the sleep cycle – before you’ve even had the chance to transition into NREM3?

The opportunity for restorative, deep sleep gets interrupted, and when you finally get the chance to resume sleeping, you probably won’t get to pick up where you left off. Instead, you’ll start over again with light sleep. And if keeps happening, you might end up feeling pretty wretched in the morning – and worse than might be expected based on the sheer amount of time that you spent sleeping.

This, at any rate, is a favored theory. How does it stack up against the evidence?

Experimental evidence: Interrupted sleep worsens mood and frazzles attention

In one of my favorite sleep experiments, Michal Kahn and her colleagues at the University of Tel Aviv recruited 61 young adults (healthy college students free of baby-related responsibilities) and asked them to wear wrist actographs at night. Actigraphs detect movement, providing researchers with an objective way to estimate sleep time.

Kahn’s team measured sleep on a normal night, and checked participants’ psychological responses the following day — measuring their moods, as well as their ability to stay focused during a demanding attention task.

In addition, the researchers randomly-assigned each participant to one of two treatment conditions:

• a night of sleep restriction (permitted to sleep no more than 4 hours at night); or
• a night of induced wakings (forced to awaken 4 times, over the course of 8 hours).

People in the sleep restriction group weren’t allowed to sleep until 3am, and they were awakened at 7am.

By contrast, people in the induced wakings group had the opportunity to sleep more. They were in bed for about 8 hours total. But they were also awakened every 90 minutes with a phone call, and asked (each time) to perform a 10-minute task before going back to sleep. It was a bit like responding to a baby, but without all the crying and fuss.

The day after the sleep manipulation, Kahn’s team tested everyone’s moods and attention performance, and compared the results with the previously-measured baselines. What were the results?

As you might expect, all the participants felt worse. They felt more tired, depressed, and confused, and they experienced a dramatic deterioration in sustained attention. You wouldn’t want them driving a car, or operating heavy machinery.

But here’s where it gets really interesting. Although the people in the “induced wakings” group got more sleep overall (on average, about 2 hours more), they performed just as poorly as people in the “sleep restriction” group. In fact, on one attention test, the scores of both groups were nearly identical (Kahn et al 2014).

And what might happen if you could ensure that both groups got exactly the same amount of sleep? Researchers from another lab tested this in a study focusing on moods. They found that — holding total sleep time constant — sleep fragmentation left folks even worse off than sleep restriction. Both treatments resulted in the loss of good moods. But the effect was bigger for people with fragmented sleep (Finan et al 2015).

Experimental evidence: Interrupted sleep can also make people more sensitive to pain

This has been replicated in numerous experiments: Forced awakenings at night make people more sensitive to pain the next day (e.g., Irwin et al 2023; Hertel et al 2023; Smith et al 2019; Iacovides 2017).

What about long-term effects?

Experiments have addressed only the short-term effects of interrupted sleep and induced wakings. What happens when parents keeping suffering with this lifestyle — for months on end?

As noted above, slow-wave sleep is associated with some really important physiological functions that contribute to our long-term well-being. So you might naturally worry that months of baby-initiated night wakings are going to have a lasting impact — beyond the misery that can come with daytime sleepiness, impaired attention, worsened mood, and greater sensitivity to pain. What does research tell us about that?

It would be helpful if we had studies designed to address this specific concern. I haven’t seen any. But I see a lot of evidence that is relevant to the question, and I think it’s very hopeful evidence. Here’s why.

Hopeful reason #1: The brain adapts to a sudden deficit by prioritizing slow-wave sleep during subsequent sleep bouts.

I mentioned this above. When people are deprived of slow-wave sleep, it changes their subsequent sleep cycles. The sleep-starved brain cuts back on light sleep so it can devote that time to slow-wave sleep. In many cases, it may also make slow-wave sleep more intense — so that brain waves are even slower, deeper.

In effect, your brain reacts to the sudden challenge of exhausting baby-care by making your sleep-time more efficient. And this is a very hopeful thing. It means that you can get more benefits from less sleep. Even a 30-minute nap can have substantial, restorative effects.

Hopeful reason #2: If you are able to get a modestly consolidated block of sleep at the beginning of the night, it’s likely that your brain will be able to secure much of the slow-wave activity you need.

Even when they aren’t sleep-deprived, adults get most of their NREM3 sleep during the first two sleep cycles of the night. So if you can protect the first 3-4 hours of sleep, you will probably feel much better. It’s a less ambitious (and more attainable) goal than waiting for your baby to get through 6-, 7-, or 8- hours of the night without waking you.

Hopeful reason #3: The interrupted sleep associated with infant care is quite different than other, more severe types of sleep disruption.

If you’re unlucky (as I was, with one of my babies) you might have a newborn who awakens very frequently. But even with these infants, the frequency of wakings is low compared with what happens to folks struggling with certain medical conditions.

For example, you might have heard that sleep is fragmented for people with obstructive sleep apnea, and that this fragmentation may be responsible for some of the chronic health problems that accompany obstructive sleep apnea. Can we look at this research, and use it to make similar predictions about parents who are struggling with infant-triggered night wakings?

No, because fragmentation is much more severe for people with clinically significant obstructive sleep apnea. Their sleep is being disturbed by respiratory emergencies that occur many times per hour (Malhotra et al 2021), and the folks may get through the night with extremely scant amounts of slow-wave sleep (e.g., Ju et al 2019; Ren et al 2020). So while we might use similar words to describe sleep disruption in tired parents (on the one hand) and in patients with obstructive sleep apnea (on the other hand), these are actually very different phenomena. There’s good reason to think the potential harms are not comparable.

What can parents do to cope with interrupted sleep?

I think it’s helpful to understand how interrupted sleep causes impairments in our well-being and ability to function. In my view, tired parents everywhere should feel validated by the research. We aren’t crazy. Getting sleep in bits and pieces isn’t as restorative as sleeping in a consolidated bout.

But we can use the research for more than validating our misery. We can also take some of the more hopeful information, and use it to our advantage. Here are some tips.

Are you dealing with a crazy, newborn sleep schedule? Take naps.

In sleep restriction experiments, people have experienced many, immediate consequences – attention problems, immune system disturbances, and heightened pain sensitivity. But they were also able make major improvements by taking naps the following day (Vgontzas  et al 2007; Faraut et al 2011; Faraut, Nakib et al 2015; Faraut, Léger, et al 2015; Saletin et al 2017).

In some studies, a single nap (30 or 45 minutes long) yielded results. In others, people got relief from two, 30-minute naps – one in the morning, the other in the afternoon. Either way, napping really helped sufferers cope with severe, unavoidable sleep restriction.

Do what you can to protect the first 3-4 hours of your nightly sleep.

This goes back to what I mentioned above. If you can get through the first 3-4 hours without waking, you’ll be better off. So if you have a partner to help with nighttime care, consider planning each other’s shifts with this in mind. Can each of you come away with a substantial block of uninterrupted sleep? In addition, you can also try to stretch out your baby’s sleeping bouts by using a method called “dream-feeding.” Read more about it here.

Feeling too wound-up to sleep? Try to tame daytime stressors, and consider progressive muscle relaxation.

Worries. Stresses. Hassles. Parents have a lot on their minds, and this can switch us into a mode of hyper-vigilance, making it harder for us to fall asleep quickly when we’re given the chance. Moreover, studies attest to our everyday experience: When we expect that something is going to wake us up at night — when we’re “on call” — it can interfere with our ability to sleep well (e.g., Wuyts et al 2012).

What can we do about this problem? As you might imagine, therapies that target stress management (like cognitive behavioral therapy) help people sleep better (Vega-Escaño et al 2020). So do pre-sleep relaxation techniques. A promising one to try is progressive muscle relaxation — a practice where you selectively contract, and then release, different muscle groups in your body. It can reduce anxiety, making it easier for us to fall asleep. And it’s also been found to increase the percentage of time we spend in slow-wave sleep (Simon et al 2022). If you click on this link, you can download a one-page PDF to this technique, offered by the University of Washington. For a variety of tips on stress management, check out this Parenting Science article.

Watch out for caffeine.

It doesn’t just interfere with drowsiness. It also decreases slow-wave sleep during those much-needed, recovery naps (Carrier et al 2009).

Got an older child – old enough not to require frequent, nighttime feedings? Try these gentle sleep training methods.

You’ve doubtless heard of “cry it out” techniques – sleep training methods that involve leaving babies alone to cry for several minutes or more. Such methods can help exhausted, desperate parents get better sleep at night. But the process can be stressful, and research suggests that alternative “gentle” tactics can be just as effective. Read more about it here.

Is your child waking you up because of nightmares? Or night terrors?

Toddlers and older kids may awaken us because they are experiencing nightmares, or, alternately, because they are struggling with a peculiar type of sleep disruption called a “night terror” or “sleep terror.” For information about these conditions, and evidence-based tips for handling them, see my article, “Nightmares and night terrors in children: How to identify the problem, and help kids sleep more peacefully.”

Consider using “pink noise” to boost slow-wave sleep activity at night.

White noise contains a mix of sound frequencies to produce a “whooshing” or static-like sound. Pink noise is similar, but it gives more emphasis to bass frequencies, and reduces the intensity or volume of less soothing, high-frequency sounds. Can a white or pink noise machine help you sleep better? The research isn’t conclusive at this time, and there are safety concerns: To protect your hearing, it’s important to keep devices turned down to a safe volume, and place them at a safe distance from your ears.

But experimental studies hint that these machines can help muffle the sudden, intrusive sounds that can disrupt sleep and reduce sleep quality. For instance, one study found that new parents tended to reduce WASO (wake after sleep onset) after introducing white noise to the sleep environment (Lee and Gay 2011). And pink noise may be a better bet, with a number of recent studies suggesting that it may actually enhance slow-wave sleep (Capezuti et al 2022).

Try not to catastrophize, ruminate, or blame yourself if you’re coping with frequent night wakings.

Sleep disruptions make us ruminate about the things that are upsetting us (Benkirane et al 2022), and, as we’ve already noted, parents can have a lot to feel stressed about – including their lack of sleep. But thinking thoughts like “these night wakings are killing me” make it even harder to get the quality sleep you need. It just creates negative feelings that interfere with drowsiness and the ability to sleep deeply.

Remind yourself that night wakings are normal and natural. You shouldn’t feel that you’ve done something wrong if your baby is slow to reach the milestone of “sleeping through the night.” And remember: When infant sleep researchers talk about “sleeping through the night,” they don’t mean that an infant is sleeping continuously, all night long. As I explain elsewhere, it isn’t that babies stop experiencing night wakings. It’s that they learn to fall back to sleep without signaling us, so that we can sleep for 5 hours or more without being awakened.

Be protective of your mental health

Sleep fragmentation doesn’t just cause temporary mood changes and excessive daytime sleepiness. It’s also associated with the development of mood disorders and postpartum depression (Goyal et al 2009). So monitor yourself for symptoms, and don’t be dismissive of your emotional needs. Learn more about the impact of postpartum stress and postpartum depression in this articles:

More reading about the challenges faced by tired parents

Looking for additional ways to improve your sleep? See these baby sleep tips, as well as my article about the common causes of sleep trouble in babies, and what you can do about it. If you have a toddler or older child, see this trouble-shooting guide to bedtime problems.

In addition, you might be interested in these Parenting Science offerings:

References: The effects of interrupted, fragmented sleep

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Content last modified 7/11/2023

image of mother bottle-feeding baby by Chanintorn.v- / shutterstock

image of tired father holding infant by Frame Stock Footage / shutterstock

A few sentences in this article appeared previously in a BabyCenter blog post written by the same author.

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