How does sugar affect your blood glucose levels?
Believe it or not, your body is programmed to crave sugar. This is because, back in our hunter and gatherer days, the sugar derived from fruit was a vital source of energy, helping to fuel our bodies during vigorous activities. The problem is that, in recent decades, we’ve started consuming too much sugar.
For example, NHS guidelines advise that we try not to eat more than 30g of sugar a day1 but you can find almost half of this amount in certain popular food products! It’s never been easier to overindulge and this can have serious repercussions for your blood glucose levels.
As I’ve mentioned, sugar that’s circulating in your bloodstream can be used as a form of energy. However, any sugar that isn’t needed will get stored in your cells to be utilised later. This prevents your blood glucose levels from becoming too high and insulin plays an important role in the process, signalling to your cells to absorb any excess sugar.
However, if you consume sugar on a regular basis, this means that your blood glucose levels will be repeatedly elevated and your cells will become more and more resistant to the effects of insulin. Your body will be forced to secrete more insulin which may cause what is known as a ‘crash’ when your blood glucose levels rapidly drop. Fluctuating blood sugar levels can have a knock on effect on your health, causing symptoms such as:
- Urge to urinate
- Increased thirst
Do your blood glucose levels influence your sleep?
Okay, so a spike in your blood glucose levels isn’t ideal, but how does it affect your sleep? Well, fluctuating blood glucose levels can have a number of different impacts which I shall explore in a bit more detail below!
Fluctuating blood glucose levels can inhibit your production of melatonin: Melatonin, also known as the sleep hormone, is usually secreted in the early evening as a reaction to the decreasing levels of daylight. It helps your body to wind down and promotes feelings of sleepiness, making it easier for you to nod off when the time comes. However, eating too many sugary treats and refined carbohydrates can elevate your blood sugar levels and consequently cause a crash. This rapid drop in blood sugar may upset your adrenals and stimulate the release of cortisol, a stress hormone which can delay your production of melatonin and slow down your digestive system.
Fluctuating blood glucose levels can decrease your deep sleep: The subsequent sugar crash you may experience while you sleep doesn’t always wake you up fully, but it can push you out of deep sleep and into a light sleep phase. This means that you’ll be more susceptible to environmental disturbances and it also means that you won’t be exposed to the restorative benefits of sleep either! Deep sleep is when your body carries out essential repair works, without which you may find several key bodily functions impaired, such as your immune system and digestive system. It also means that, despite seemingly sleeping through the night, you may still feel tired and sluggish the following day!
Fluctuating blood glucose levels can reduce the activity of orexin cells: Not only can too much sugar pull you out of deep sleep, it can also reduce the activity of orexin cells. Orexin is what is known as a neuropeptide, produced in the hypothalamus region of your brain. It helps to promote wakefulness by interacting with other neurotransmitters such as serotonin and melatonin. If the activity of orexin cells is reduced it can mean that you will experience fatigue during the day – those that suffer from narcolepsy, for example, often have abnormally low levels of orexin!2
Fluctuating blood glucose levels can upset your digestive system: If your blood sugar levels are oscillating between highs and lows it may affect your digestive system. While you sleep, your digestive system generally slows down and enters a rest phase – this is why you are advised not to eat before bed! However, if you’ve been bingeing on sugar snacks and processed foods, your digestive system will struggle to cope with the increased demand so you may be woken up in the middle of the night by digestive complaints. You also have to consider that, when your blood glucose levels are high, your kidneys will work to excrete this excess, meaning you will experience an increased urge to urinate too!
Can sleep deprivation affect your blood glucose levels?
The downside of fluctuating blood glucose levels is that it can affect your sleep pattern but, unfortunately, your sleep patterns can also influence your blood sugar levels!
Firstly, sleep deprivation can affect your production of the hormones that regulate your appetite. This means that you’ll find yourself craving more sugary, carb-rich foods after a poor night of sleep and these types of foods will then go on to raise your blood sugar levels, creating a vicious cycle! How much sleep you get can also affect your body’s ability to metabolise glucose.
This calls back to the effect of blood glucose on deep sleep. When you enter deep sleep, your brain does not use as much glucose so it’s believed that this phase of sleep is highly beneficial for your blood glucose levels. In one experiment, researchers altered the participants’ sleep, preventing them from entering deep sleep. As a result, after being deprived of deep sleep, the participants’ insulin sensitivity and glucose tolerance was drastically decreased by around 25%3, putting them at risk of developing high blood glucose levels!
What should I be eating for my sleep?
Cravings can be difficult to ignore – at some point or other we all find ourselves desperate for a slice of cake or a bar of chocolate – and, provided it’s just an occasional treat and not an everyday occurrence, there’s nothing wrong with indulging your sweet tooth.
However, on a daily basis it’s important to consider your diet carefully. I’ve spoken at length about diet and sleep which is why, if you’re looking for further advice, I’d highly recommend checking out a few of the blogs below!
Is your lack of sleep making you overeat?
What do your food cravings really mean?
What foods can you eat to help you sleep?
6 surprising foods to avoid before bedtime
Is magnesium a miracle mineral for sleep?