In Part 1 of this mini-series, I summarised recent research demonstrating the benefits of better nutrition – specifically, increased consumption of fruits, vegetables, mushrooms and legumes – for reducing the risk of developing depression and anxiety.
In Part 2, I delved into recent research on the link between physical activity and the prevention and treatment of depression and anxiety.
And in Part 3, I explored recent research on the effect of getting outdoors on mood and anxiety.
Now, in Part 4, let’s dig into the latest research on the role of human connection (including the unique form of mother-infant connection embodied in breastfeeding) and sleep in staving off depression and anxiety.
Human connection, sleep, depression and anxiety: Put that dang device down, and spend time with someone (and if you decide to become life partners, sleep in the same bed as them)
I discussed the connection between lack of meaningful human connection and illness in a previous article, Hearts, minds and bodies on fire: Loneliness, social isolation, inflammation and COVID-19.
It’s intuitively obvious that creatures as inherently social as we humans are liable to become miserable if we’re deprived of contact with other people. As usual though, researchers are interested in finding out why – that is, what is the mechanism linking social isolation and loneliness with both physical and mental illness? Which leads me to…
Study #1 – Getting under the skin: Social isolation and biological markers in the National Health and Aging Trends Study
Researchers analysed data from the National Health and Aging Trends Study (NHATS), involving a nationally representative sample of 4648 US Medicare beneficiaries aged 65 years and older. They examined the relationship between social isolation and two biological markers of inflammation, interleukin-6 (IL-6) and high-sensitivity C-reactive protein (hs-CRP).
IL-6 has been shown in previous studies to be linked to both the onset and continuation of major depressive disorder; individuals with genetic profiles that cause aberrant IL-6 signalling have higher rates of depressive symptoms. Dysregulation of IL-6 has also been linked with the neuropsychiatric symptoms associated with long COVID, including anxiety, depression, insomnia and fatigue.
Likewise, the UK Biobank study has previously identified a link between elevated CRP and anxiety, although this link may be mediated by the effect of both anxiety and depression on health-related behaviours that are linked to increased inflammation.
And the NHATS study provided compelling evidence that social isolation is one of the factors that drives up inflammation, with isolated elders having significantly higher levels of both IL-6 and hs-CRP.
And you know what lowers these inflammatory markers? Horticultural therapy, which is a fancy name for group activities, guided by a trained therapist, involving park visits and gardening activities. More reasons to go outside (preferably with other people) and get your hands dirty, as I recommended in Part 3!
Aside from the effects of what I’ve dubbed ‘vitamin N’ – as in Nature – horticultural therapy facilitates in-person social support, as opposed to the tawdry simulacrum offered by so-called social media. And that brings us to…
Study #2 – Problematic social media use and social support received in real-life versus on social media: Associations with depression, anxiety and social isolation
This study utilised an online survey of just over 400 young adult university students to assess the relationship between real-life social support (having at least one person to whom they could turn for help ‘in the flesh’), online social support (having at least one person on social media to whom they could turn for help), problematic social media use (addiction-like behaviours and effects) and symptoms of anxiety and depression.
The researchers found that only real-life social support was protective against depression, anxiety and social isolation, whilst those who overused social media were more likely to be depressed, anxious and socially isolated:
“Problematic social media use was significantly associated with reduced real-life social support and increased social support from social media. Problematic social media use was also significantly associated with increased depression, anxiety, and social isolation. Real-life social support was significantly associated with reduced depression, anxiety, and social isolation. However, social support on social media was not significantly associated with depression, anxiety, and social isolation. With regard to our research question, problematic social media use had a significant indirect effect on all three measures of mental health when mediated by real-life social support, such that an increase in problematic social media use was associated with increased depression, anxiety, and social isolation through reduced social support.”
Problematic social media use and social support received in real-life versus on social media: Associations with depression, anxiety and social isolation
To put it in the simplest possible terms, all the Facebook/Instagram/Snapchat/Tik Tok ‘friends’ in the world don’t substitute for having real-life friends whom you can see, hear, touch and smell (and yes, our olfactory sense plays a large and underappreciated role in human relationships). No matter how many of your online ‘friends’ like or comment on your posts, only real-world friendships buffer you against becoming depressed or anxious – and these real-world friendships help save you from spiralling into the type of pathological use of social media that is liable to make you more depressed and anxious.
Humans are engineered by millions of years of evolution to connect with each other ‘in the flesh’. Even the most sophisticated digital interfaces cannot possibly substitute for the multi-level richness of in-person contact. The concerted push by various social, political and economic forces to displace real-life with digitally-mediated human contact that results in humans behaving just like rats seeking food rewards is resulting in a rapid increase in anxiety and depression, especially in so-called ‘digital natives’ – the demographic groups who have grown up with these technologies.
In many ways, the template for healthy human connection is set in the very early months of life when, ideally, infants are breastfed by their mother*. There is extensive evidence of the benefits of prolonged breastfeeding for both infants and their mothers, as I’ve documented in Healthy mum, healthy baby: Part 3.
And now we can add reduced risk of postpartum depression to that roll call of benefits. Bring on…
Study #3 – The significance of breastfeeding practices on postpartum depression risk
Researchers accessed data from almost 30 000 US women who had answered the 2016 Pregnancy Risk Assessment Monitoring System (PRAMS) questionnaire, to assess the relationship between breastfeeding and postpartum depression, which is estimated to affect 11-20 per cent of women who give birth in the US each year.
After carrying out statistical adjustments to account for a variety of potential confounding factors including age, race, marital status, education, whether they had wanted to become pregnant, and whether they had intended to breastfeed, the researchers found that women who were currently breastfeeding at the time they answered the questionnaire (which was administered when they were between 0 and 6 months postpartum) had a 13 per cent lower risk of suffering from postpartum depression than women who were not currently breastfeeding. Furthermore, the longer that mothers continued to breastfed their babies, the lower their risk of developing postpartum depression.
And interestingly, the results held regardless of whether or not the women had intended to breastfeed, suggesting that there is a biological, rather than purely psychosocial, connection between breastfeeding and maternal mental health.
These results were largely confirmed by…
Study #4 – The Effects of Breastfeeding on Maternal Mental Health: A Systematic Review
This paper synthesised the findings of 55 studies on the effects of breastfeeding on mothers’ mental health. Of the 36 studies that found significant relationships between breastfeeding and maternal mental health outcomes – namely symptoms of postpartum depression and anxiety – “29 found that breastfeeding is associated with fewer mental health symptoms, one found it was associated with more, and six reported a mixed association between breastfeeding and mental health.”
Unsurprisingly, “five studies found that breastfeeding challenges were associated with a higher risk of negative mental health symptoms,” underscoring the importance of timely intervention by skilled lactation consultants**.
The authors of the review pointed out that the protective effects of breastfeeding against postpartum depression apply despite “the challenges inherent to breastfeeding, such as lack of sleep”.
Many women introduce a night-time bottle of formula in hopes that doing so will ease their sleep deprivation by causing their babies to sleep through the night. However, while research indicates that formula-feeding does not reduce night-waking in infants, and that mothers who breastfeed get more sleep than mothers who formula-feed (either partially or fully), ‘comping’ with formula does cause breast milk supply to drop, which frequently leads mothers to abandon breastfeeding entirely. And that, according to the review article, puts them at higher risk of developing postpartum depression and anxiety.
Speaking of sleep, there’s evidence for a bidirectional relationship between sleep disturbances and both anxiety and depression. That is, people who experience sleep disturbances are more likely to become depressed and/or anxious, and depressed and anxious people are more likely to develop sleep disturbances.
Anxiety and depression are both characterised by unwanted and unpleasant thoughts which individuals struggle to block out, which leads me to…
Study #5 – Losing Control: Sleep Deprivation Impairs the Suppression of Unwanted Thoughts
Noting that “individuals suffering from psychiatric conditions such as posttraumatic stress disorder (PTSD) and major depressive disorder (MDD) typically experience a disproportionate number of unwanted memory intrusions, and difficulties in limiting the duration and recurrence of these intrusions compound negative mood and affective dysregulation”, researchers designed an experiment to test the effects of sleep deprivation on participants’ ability to control intrusive memories and thoughts.
Participants were first shown photographs of emotionally neutral faces paired with either neutral or negative scenes, and trained to either visualise or deliberately suppress the scenes paired with the faces. Then they were either allowed to sleep uninterrupted for up to 8 hours, or completely deprived of sleep overnight.
The following morning, they were shown just the faces again, and asked to try to suppress thoughts of the scenes with which these faces had been paired the night before.
While well-slept participants became better and better at suppressing unwanted thoughts with practise, those who had been deprived of sleep showed little improvement in their ability to prevent intrusive thoughts. In fact, sleep-deprived participants had nearly 50 per cent more unwanted thoughts than those who completed the task after a good night’s sleep.
And because the sleep deprivation interfered with their ability to keep unwanted thoughts at bay, their bodies showed greater psychophysiological reaction to intrusive thoughts (measured by increased sweating). In other words, sleep-deprived people showed an amped-up stress response because they weren’t able to keep out intrusive thoughts.
Anyone who has ever felt anxious will immediately recognise the significance of this finding. Anxious people are hyper-aware of their bodies’ indicators of stress, such as sweating and increased heart rate. The more these symptoms occur, the more anxious they become, which amplifies the symptoms, which makes them feel even more anxious.
And rumination – endlessly churning through the same sequence of thoughts about a current problem – is a hallmark of depression.
The study’s authors drew all these threads together in the discussion of their findings:
“Our data raise the possibility that poor intrusion control may help bridge the gap between disturbed sleep and psychiatric symptoms: Insufficient sleep might increase memory intrusions while also nullifying the benefits of retrieval suppression for regulating affect. The onset of intrusive thoughts and affective dysfunction following bouts of poor sleep could create a vicious cycle whereby upsetting intrusions and emotional distress exacerbate sleep problems… inhibiting the sleep needed to support recovery.”
Losing Control: Sleep Deprivation Impairs the Suppression of Unwanted Thoughts
Oh, and just because nature enjoys a good joke at our expense, guess what happens when we find ourselves awake in the early hours of the morning? A combination of neurobiological changes tied to our circadian rhythm makes us more prone to “3am thinking”, characterised by rumination and catastrophising.
What might help us sleep better and thereby be more resistant to anxiety and depression? Exercise and time in nature certainly help, as discussed in Parts 2 and 3. And so does sleeping in the same bed as one’s romantic partner. So let’s talk about…
Study #6 – Adults Sleep Better Together Than They Do Alone
According to data collected in the Sleep and Health Activity, Diet, Environment, and Socialization (SHADES) study of just over 1000 working-age adults from southeastern Pennsylvania, adults who shared a bed with their spouse or romantic partner reported less severe insomnia, less fatigue, more time asleep and lower risk of sleep apnoea, along with lower depression, anxiety, and stress scores, and greater social support and satisfaction with life and relationships, than those who slept alone.
That’s good news for people who are concerned that their partner’s nocturnal movements and occasional incoherent mumblings might be messing with their sleep – quite to the contrary (although persistent loud snoring might test one’s limits).
Unfortunately, sleeping with children in the bed wasn’t such a happy story: adults who reported that their child/ren slept in their bed most nights had greater insomnia severity, greater sleep apnoea risk, and were more stressed.
Having slept with a couple of miniature human starfish in my time, I can understand why. Children have a capacity for monopolising bed real estate (and blankets) that is inversely proportional to their size.
Summing up
We naked apes are highly social creatures who absolutely require meaningful in-person connection with other human beings in order to flourish psychologically. Spending time with our friends, breastfeeding our babies and sleeping alongside our romantic partners all help to buffer us against depression and anxiety, the modern-day plagues that increasingly bedevil us as modernity imposes ever more unnatural forms of duress on our stone-age bodies and minds.
It’s not coincidental that the depression- and anxiety-reducing behaviours discussed in parts 1-3 of this series – increasing our intake of unprocessed plant foods, physical activity levels and time spent outdoors in nature – are also congruent with our evolutionary history.
For all of the astonishing technological progress enabled by the remarkable ingenuity of our species, it turns out that we achieve the highest state of psychological flourishing when we choose to replicate, to the fullest extent possible, the daily practices of our ancient forebears.
And, irony of ironies, the rationalist discipline of science – the Siamese twin of the technology that undergirds our modern way of life – is proving that we sophisticated twenty-first century humans are screwing ourselves and our children up, nine ways to Sunday, by deviating so dramatically from the ways of living of our supposedly benighted ancestors. Nature really does have a sense of humour.
* The correct term for an individual who gives birth to a human infant is ‘mother’, not ‘birthing person’, a deeply misogynistic term that strips women (defined as ‘adult human females’) of the inherent dignity of their biological function, which is to participate in the continuation of the human species by gestating, giving birth to and nourishing babies.
** There are, regrettably, conditions which make breastfeeding genuinely impossible for some mothers and their babies; human milk banking is the best solution to this problem. However, breastfeeding by the infant’s own mother should be encouraged and maximally supported whenever possible in order to promote optimal infant development and maternal physical and mental health.
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