New Research suggests certain types of carbohydrates are risk factors for poor sleep in menopausal women.
The relationship between insomnia and diet is an emerging area of interest as sleep disorders gain greater attention in mental and physical health studies. But very few of these studies have been undertaken on women in menopause and post-menopause, which is why this one caught my eye. Thousands of menopausal and postmenopausal women who participated in the Women’s Health Initiative Observational Study reported on their carbohydrate intake and type and their sleep quality and researchers followed them up for 3 years.
The findings support what I teach women on the MyMT™ programmes – that the type of carbohydrates we eat matter to our sleep. And it’s all about the Glycemic Index (GI) of the carbs. Those carbohydrate foods with a high Glycemic Index diets may be a risk-factor for insomnia, especially in post-menopausal women. The large prospective study (Gangwisch, Hale et al, 2019) demonstrated that progressively higher dietary GI was associated with increased insomnia incidence over 3 years, after adjusting for demographic, behavioural, lifestyle, psychosocial and medical factors.
I’ve talked about the GI rating of carbohydrates in my articles before.
That’s why I loved this further research from the Women’s Health Initiative data, linking the glycemic index of carbohydrates to sleep. The researchers found that added sugars, such as caloric sweeteners not naturally found in foods, typically have higher GIs, hence, the source of a sugar also influences the GI rating. And that evening fruit juice that you might have each evening before bed, gets a mention too. It’s high in GI but if you can eat the fruit instead which of course, has the fibre in it, then this lowers the GI rating which is better for you being able to get off to sleep.
The research reported that out of the 7 most commonly consumed fruits in the United States, only 4 had a low GI rating (<55 on the GI rating scale) that didn’t effect sleep as much – these were, apples, strawberries, oranges and peaches. Ripe bananas and grapes were moderate GI and watermelon has the highest GI in the fruits tested. (Gangwisch, Hale et al, 2019). So,if you like to eat something before bedtime, make sure it is a food that is Low GI, which means that food with fibre is better. The higher the fibre content of food and fruits, the better for your sleep.
One of the greatest mistakes made in diets today, is that carbohydrates need to be avoided but they are an important source of energy for all of us – what’s more important for women in menopause, is the type of carbohydrate.
But the confusion results because the term ”carbs’ is used for processed foods and foods high in sugar, so yes, we have to try and remove these sources of carbohydrates, however, fruits and vegetables are carbohydrates too. So, are grains. Hence, understanding that carbohydrates are not created equal is important and they differ in type as well as how they affect your blood sugar levels.
Women on my 12 week programmes soon learn that when our blood sugar levels are high in the evneing, then this releases insulin from our pancreas, which in turn directly impacts the secretion of our sleep hormone, melatonin. This is because your brain loves glucose and high blood sugar levels cause glucose to cross the blood brain barrier, which competes with the production of melatonin. For those of you exercising after dinner and/or eating or drinking high GI carbohydrates late at night, then this is an important point to note – it affects your sleep quality and duration, especially if you are in post-menopause.
What about starch? Should we have starch foods before bed?
Starches are complex carbohydrates. But again, all starches are not equal when it comes to the GI rating because it depends on the fibre content they contain. Sources such as white bread and boiled potatoes have high GIs, whereas other fibre-rich sources including legumes, nuts/seeds, and yams have low GI. When the researchers explored the data from the Women’s Health Initiative study, they examined different types of starches according to fibre content. As such, they found that progressively higher consumption of wholegrains was associated with lower insomnia prevalence and incidence.
Increased vegetable consumption was also associated with with decreased insomnia. The 6 most commonly consumed vegetables in America which have low GI ratings are – onions, tomatoes, lettuce (both romaine and leaf lettuce), bell peppers and cucumbers. The most commonly eaten vegetable in America is potatoes, but the researcherts noted that with most varieties and methods of cooking, potatoes have a high GI rating.
In finding a plausible mechanism between the GI ratings of foods and the connection with insomnia, the researchers suggest that when we have carbohydrate foods that have high GI ratings (whether at dinner or after dinner), then this increases blood levels of insulin. Remember that when there is a lot of glucose in our blood, the hormone insulin is released by the pancreas in order to move this glucose to the sites where it is most needed – liver, muscles and of course, our brain. If blood glucose levels are high, there is a lot of insulin released and as such, glucose is removed from our bloodstream and the result is high insulin and low blood glucose (which is now binding to insulin receptor sites), hence, this low blood glucose triggers a compensatory survival response which then lowers brain glucose. As such, our stress hormones increase (adrenaline and cortisol) which interfere with the production and release of our sleep hormone, melatonin.
I think that many of us know the symptoms of low blood and brain glucose and high stress hormones. Especially those of you who might do a lot of exercisea nd run out of energy at times. Symptoms include – heart palpitations, tremor, cold sweats, numbness, anxiety, mood swings (especially irritability and anger) and of course, hunger! If you recognise any of these symptoms and wonder if it’s related to menopause, then I would suggest you also look at your diet too.
It is well known in sleep physiology that high blood sugar levels affect your sleep and poor sleep affects your blood sugar levels. It’s a vicious cycle. As the amount of sleep decreases, blood sugar increases, escalating the issue, which sends many post-menopausal women heading towards Type 2 diabetes. It’s why I always mention to women in my Masterclass on Menopause, that sleep is more important than exercise for losing menopause fat. If we aren’t sleeping, we aren’t losing.
Brand-Miller, J. Foster-Powell, K. & Colagiuri, S. (2002). The Glucose Revolution. University of Sydney: Hodder Print.
Gangwisch J., Hale, L., St-Onge, MP, Choi, L. et al (2020). High glycemic index and glycemic load diets as risk factors for insomnia: analyses from the Women’s Health Initiative, The American Journal of Clinical Nutrition, Volume 111, Issue 2, February 2020, Pages 429–439, https://doi.org/10.1093/ajcn/nqz275
St-Onge MP, Roberts A, Shechter A, Choudhury AR. (2016). Fiber and saturated fat are associated with sleep arousals and slow wave sleep. J Clin Sleep Med 2016;12(1):19–24.