Talk to a nutritionist about immune support and you’d probably expect to hear about micronutrients like vitamin C and zinc, or anti-inflammatories like ginger and turmeric.
It may surprise you to hear that the growing consensus in nutrition and functional medicine research is that SLEEP may benefit your immune system more fundamentally than anything you eat or drink. My clinic specialism is immunity and thyroid health, and for the thyroid, sleep is crucial.
But it’s all very well knowing that sleep is important – we all know it at some level. What most of us need is actually to get enough sleep ourselves.
My theory is that knowing how something works to my benefit, is brilliant for motivation.
So let’s have a look at the surprising way that sleep relates to immunity, and then consider a few specific things that we can do to support good sleep.
Sleep is PRO inflammatory – but that’s a good thing
First of all: during sleep, our immune cells mount their main response to anything that is challenging them. Sleep is, perhaps surprisingly, a pro-inflammatory state.
Inflammation gets a bad name, but correct levels of it are involved in our healthy immune response, to get rid of pathogens.
We see inflammation at work when we cut our knee: we sense pain, warmth, redness and swelling, as the body works to fight any infection and to mend the injury. A similar set-up ensues internally, unseen, when viruses and other unwelcome things enter the body.
This inflammation response happens best at night for various reasons, but one reason is that the body doesn’t have to travel or digest food then, which means there is more energy to deal with any invaders.
Cortisol and inflammation
Another reason the inflammatory fight against pathogens occurs at night, is that this is when our stress hormone cortisol is at its lowest, and cortisol is a natural anti-inflammatory.
In healthy sleepers, cortisol rises in the early morning to help us get going for the day – a bit like an internal caffeine shot. And since cortisol is naturally anti-inflammatory, this will dampen the inflammatory processes going on at night. (Chronic inflammation is involved in much disease and we want to avoid that.)
By the evening, cortisol is ideally winding down to its lowest levels. This allows the night to be a time for immune activity, and enhances the expression of antiviral proteins called cytokines. It comes as no surprise, then, that recent studies have found insufficient sleep to trigger a greater susceptibility to pneumonia and colds.
But reduced sleep can also cause heightened inflammatory responses in daytime, as well as an increased activation of the sympathetic nervous system, or fight-or-flight response. A fight-or-flight response may then interfere with digestion, triggering IBD or reflux, and generally crank up our sense of stress during the day.
Sleep, brain disconnection and immunity
Another important result of poor sleep, is the weakening of the connection between the amygdala and the pre-frontal cortex, which has an indirect but important impact on immunity. This fact is discussed at length in the recent book Brain Wash by David and Austin Perlmutter.
The amygdala is our most impulsive, instinctual section of the brain: in some ways it thinks almost like a toddler. By contrast, the prefrontal cortex thinks more like a parent: it takes the long view, considers others, chooses restraint. The Perlmutters describe a weakened connection between these two parts of the brain as a ‘dis-connection syndrome’, which makes it increasingly difficult to manage one’s own life healthily.
The logic goes that, if our prefrontal cortex is less strongly connected with our amygdala, we become more susceptible to unhelpful behaviours, even when we know they aren’t helpful – for example, eating too much sugar (which we crave more when tired), or watching screens too late at night (perhaps an attempt to ‘fly’ from stress). As we know, these behaviours can themselves disrupt sleep further, which then further reduces our body’s ability to fight viruses and other pathogens.
All of which to say, the most perfect diet will not make up for bad sleep. And since getting good sleep is the primary way to support healthy immunity, this is crucial for all autoimmune thyroid issues too.
Tips to support your thyroid, sleep and immunity
Many of us may be experiencing unusual sleep patterns at present, whether that’s thanks to a change in routine or diet, concerns about people or circumstances, or just absorbing the overload of emotion that’s swilling around one’s social media or news feed.
Thankfully, unlike supplements and special foods, sleep is free. And although sometimes bigger interventions are required, there are plenty of ways to help sleep become as deep and restful as possible. (However - I needed some nutrition intervention once, after I was insomniac for years; feel free to contact me for a free chat if you think this is you too.)
You probably already know about limiting caffeine and alcohol, the benefits of exercise, and not looking at screens before bed. Here are a few extra thoughts.
1. Daylight very first thing
Soon after waking, put your face outside, or lean out of the window and see the sun or daylight. Even better, walk outside for a while. Early daylight impacts photoreceptors in the body which help to set the body clock, or circadian rhythm, to be ready for sleep at night.
2. Darkness and cold
By the same token, too much light at night confuses the body clock. Make your bedroom as dark as possible, and use very low lights before sleeping. And perhaps consider an eye mask too. Cool rooms and not too many layers on the bed may help the body to rest more deeply. (Also: you may also like my previous blog on mouth-taping which discusses a more unusual sleep aid!)
3. More bedtime
We are generally pretty good at signalling to children when to sleep, with a reassuring sequence of baths and story time and talking in low light. Somehow, we expect our adult selves to drop off without any of those same signals. Perhaps lockdown is the perfect time to try retiring just a little earlier at night. Journalling and gratitude (written or spoken) are classic ways to process the day and clear down the mind.
4. Bedtime baths and magnesium
I recommend semi-regular Epsom Salt (magnesium sulfate) baths before bed to almost all my clients. The magnesium in the salts can be absorbed through the skin and helps support deep sleep, while the stillness of the bath creates a lovely full stop to the energy of the day. Dim light from a few candles round the bath, helps signal to the brain that night is here.
5. Adding noise
If you sleep lightly, using white noise can mask background sounds in the environment, and support deeper sleep. I actually run a white noise app on an old mobile phone (in airplane mode) but there are more elegant options like actual white noise machines.
I hope this encourages you that there easy and free things to be done to support your sleep – and that in doing them, you're support a central plank of good immunity, not just a side-issue.
As I said earlier, feel free to get in touch with any questions you have about sleep, immunity, or anything else. I also offer free 15-minute phone consultations, without obligation to book anything.
To your best of immune health,
Clare
Clare Backhouse, dipION, Registered Nutritionist MBANT,
Registered Nutritional Therapist CNHC
Consultations online
References and resources
AlDabal, L., BaHammam, A.S., 2011. Metabolic, Endocrine, and Immune Consequences of Sleep Deprivation. Open Respir Med J 5, 31–43.
Ali, T., Choe, J., Awab, A., Wagener, T.L., Orr, W.C., 2013. Sleep, immunity and inflammation in gastrointestinal disorders. World J Gastroenterol 19, 9231–9239.
Besedovsky, L., Lange, T., Born, J., 2012. Sleep and immune function. Eur J Physiol 463, 121–137.
Irwin, M.R., 2019. Sleep and inflammation: partners in sickness and in health. Nature Reviews Immunology 19, 702–715.
Lin, C.-L., Liu, T.-C., Chung, C.-H., Chien, W.-C., 2017. Risk of pneumonia in patients with insomnia: A nationwide population-based retrospective cohort study. Journal of Infection and Public Health 11.
Nayak, S.K., Jegla, T., Panda, S., 2007. Role of a novel photopigment, melanopsin, in behavioral adaptation to light. Cell. Mol. Life Sci. 64, 144–154.
Perlmutter, D., 2020. Brain Wash: Detox Your Mind for Clearer Thinking, Deeper Relationships and Lasting Happiness. Yellow Kite.
Prather, A.A., Leung, C.W., 2016. Association of Insufficient Sleep With Respiratory Infection Among Adults in the United States. JAMA Intern Med 176, 850–852.
Reinberg, A., Touitou, Y., Lewy, H., Mechkouri, M., 2010. Habitual moderate alcohol consumption desynchronizes circadian physiologic rhythms and affects reaction-time performance. Chronobiol. Int. 27, 1930–1942.