Can Sourdough Sandwiches Help You Sleep?

by Ed Cooper

Across years of nutritional dogma – where one food is hailed as healthy, only to be later vilified – few pantry staples have enjoyed such a dramatic shift as sourdough bread. Once the preserve of artisan bakers and niche cafés, sourdough now crops up everywhere from supermarket aisles to home kitchen counters and high-street sandwich bars, celebrated not just for its flavour, but also for its new wellbeing credentials.

Sourdough’s slow, natural fermentation process fits in neatly with modern wellness philosophy, and more and more consumers are opting for sourdough loaves and products over mass-produced, preservative-filled alternatives. It was only a matter of time, then, before biohackers took it a step further, claiming that certain ingredients in sourdough could be the secret to a good night’s sleep. “I’ll eat sourdough every evening for serotonin and melatonin,” actress and biohacker Davinia Taylor told The Standard last fall. “That cosy carb coma actually sets me up for better sleep.”

But is there any substance to the idea? To help separate nutritional fact from fiction, we spoke to two nutritionists for their take on this interesting new bit of nutritional science.

What is sourdough bread?

Let’s start with a basic understanding of what differentiates sourdough bread from traditional store-bought sliced bread. “Proper sourdough is typically just flour, water, salt, and a starter,” says Rachel Butcher, ANutr, SENr, head of nutrition at Natural Fitness Food. “Many sliced breads contain emulsifiers, preservatives and added sugars, so switching to sourdough from a regular store-bought white loaf could certainly be considered a good choice if you are looking to make some positive nutritional choices.”

However, not all sourdough is nutritionally equal, says Butcher. “Wholemeal or mixed-grain sourdough provides more fibre and micronutrients than white sourdough.” Many sourdough-style loaves on the market use yeast and flavouring with minimal fermentation, “so the benefits of these are smaller,” she adds.

Is sourdough good for you?

When unpacking the health benefits of sourdough, there’s plenty to scrutinise — including the specific flour used in the recipe and suggested portion sizing — but “sourdough can absolutely fit within a healthy diet, particularly when made from wholegrain flour,” says Paul Garrod, IOPN Dip. SENr, a sports nutritionist who has worked in sports nutrition for over a decade. Garrod points out that sourdough tends to have a lower glycemic impact than many refined breads and is higher in minerals like iron and zinc thanks to the lactic acid bacteria produced during fermentation. It’s texture and flavor also make it more satisfying than other types of bread, he adds.

So, is sourdough really the best thing since sliced bread? Well, that depends. “The overall nutritional quality heavily depends on the flour used, as wholegrain sourdough will generally offer more fibre and nutrients,” says Garrod. Ultimately, sourdough “is better described as a higher quality bread, rather than a health food in itself.”

Can it actually help me sleep better?

Now, let’s get down to the real question here: Can a slice (or two, or three…) of sourdough genuinely promote a restful slumber, or is that just hype? For the experts, this answer is nuanced.

Unsurprisingly, there’s not a ton of research directly looking at sourdough consumption and improved sleep to point to. “That said, the idea isn’t entirely implausible, as sourdough’s slower effect on blood sugar may help avoid large evening glucose spikes and crashes, which can disrupt sleep for some people,” Garrod says. “Broadly speaking, meals that combine complex carbohydrates with protein can support the availability of tryptophan, an amino acid involved in melatonin production.” The benefit, however, “is likely indirect and related to overall meal composition rather than sourdough itself.”

Another factor in favor of sourdough’s sleep-enhancing properties lies in the way it’s made. “The fermentation process in making sourdough reduces phytates, compounds that bind minerals like iron, zinc and magnesium, improving the absorption of these minerals,” Butcher points out. This is noteworthy because magnesium and zinc both play a role in regulating GABA, a neurotransmitter that calms brain activity and can help people feel calm and even sleepy. But perhaps most importantly, GABA also plays a vital role in supporting the production of the sleep hormone melatonin. So, there’s not a direct link here, but there may be some connecting threads linking sourdough’s chemical and nutritional properties with sleep.

To sum it up? “Indirectly, sourdough could positively impact sleep,” says Butcher.

Try it for yourself

If you want to experiment yourself — and let’s face it, who wouldn’t — Butcher recommends plating up a straightforward nighttime meal that’s built around sourdough, but loading up on protein, healthy fats, and plenty of flavour to get maximum nutritional bang for your buck.

“A simple balanced meal could include sourdough toast with smoked salmon or eggs, avocado, rocket or spinach and a squeeze of lemon and drizzle of olive oil,” Butcher says, “topped with a sprinkling of seeds for extra nutritional benefits.” The protein from eggs or salmon supports satiety and blood sugar control, while the fats slow digestion and the greens add fibre, folate, and magnesium.

Alternatively, if the mood for a warm loaf of local micro-batch artisanal sourdough doesn’t strike, Garrod recommends “foods that support stable blood sugar and provide nutrients involved in sleep regulation.” These include whole grains, oats, dairy foods, nuts, seeds, kiwi fruit, cherries and foods rich in magnesium, such as leafy greens and legumes.

His parting advice? “Sleep hygiene patterns matter more than individual sleep foods,” so while certain ingredients in sourdough may offer marginal gains for sleep, don’t expect your local baker to double-up as your sleep coach.

Further reading: What Does Your Sleep Position Mean?

Further reading: Mindful Eating Over Macros: How Letting Go Can Make You Healthier

Further reading: Eat These Surprising Foods Before Bed For The Best Sleep: Tips From A Nutritionist

Further reading: The Best Supplements For Sleep (That Actually Work)