Why Blood Sugar Might Be the Sleep Factor You're Missing

A good night's sleep is imperative to the next day's success. Mood improves, focus sharpens, cognitive function increases, and appetite stays balanced. Without quality sleep, it is difficult to feel and perform at one's best on a day-to-day basis.

There are four stages of sleep and how much time is spent in specific stages determines the quality of sleep and likely how one feels the following morning.

The first two stages are considered "light" sleep. Stage one (N1) is the first stage of non-rapid eye movement (NREM) and the lightest stage, which should make up only about 5% of total sleep time. Stage two (N2) is the second stage of NREM and should make up about 45% of total sleep. Although light, this stage is still essential for recovery and brain health.

Stage three (N3) of NREM is considered "deep sleep" or "slow-wave sleep" (SWS). This is the deepest stage of sleep and should ideally consist of close to 20% of total sleep time. This stage is crucial for body recovery: tissues, muscles, and neurons repair and the immune system reboots. Without adequate deep sleep it is near impossible to recover from the previous day, and insufficient SWS leads to waking up exhausted and moody.

Stage four is rapid eye movement (REM), often referred to as the "dream state." This is a lighter stage of sleep in which the brain is in a similar state as when awake. Ideally, REM should make up close to 25% of total sleep time. Although not the deepest form of rest, it is a crucial stage for mental recovery and memory formation.

Sleep quantity refers to the total amount of sleep. Sleep quality refers to the amount of time spent in REM and SWS. Spending 40-50% of total sleep time in these stages produces more restorative sleep than spending most of the night in the first two stages. For example, someone could get eight hours of sleep but wake up feeling exhausted because they had only 15 minutes of SWS and 45 minutes of REM. Conversely, someone who gets less than 7 hours may feel completely rejuvenated because 90 minutes of their night was spent in SWS and over two hours in REM.

How Can Sleep Quality Be Supported?

There are many factors that impact SWS, including eating too close to bedtime, consuming too many refined carbohydrates and sugar and stress (elevated cortisol levels), excess caffeine consumption, and alcohol intake. All of these factors can influence how the body manages blood sugar in the hours around sleep. Eating too close to bed, especially foods high in refined carbs and sugar, causes a glucose spike followed by a crash that disrupts SWS. Elevated cortisol levels also raise blood sugar. Caffeine can potentially elevate blood sugar by triggering a slight stress response. Alcohol leads to a nighttime blood sugar crash as the liver focuses on metabolizing alcohol rather than maintaining blood sugar balance. When blood sugar is consistently fluctuating throughout the night due to daytime and evening decisions, it becomes very difficult to enter a deep rest.

A nighttime blood sugar spike, whether from a sugary beverage before bed or a meal eaten too close to bedtime, can trigger a hormonal cascade. This leads to excess insulin getting released to move glucose out of the bloodstream and into cells for immediate fuel or storage. This significantly lowers plasma glucose levels that may lead to the secretion of counterregulatory hormones, including adrenaline, cortisol, glucagon, and growth hormone. These hormones either access stored glucose for release into the bloodstream or stimulate the breakdown of tissue to convert amino acids into glucose. The release of adrenaline and cortisol activates a stress response in the body, which leads to waking up or failing to fully enter deep sleep.¹ The hormonal response to the blood sugar crash perpetuates the blood sugar rollercoaster and compromises sleep quality.

In research, experimentally-induced nighttime low blood sugar via insulin infusion during SWS has been associated with worse memory the following day.¹ In similar studies manipulating blood glucose levels at night, individuals with low glucose levels during SWS reported a decrease in vitality and feelings of contentment.² This indicates that blood glucose has a significant impact on sleep quality and recovery. This process does not just impair sleep, but it impacts how a person feels the following day. With poor sleep quality, individuals are likely more moody, reactive, fatigued, and experience poor concentration. Restricting sleep to just 5 hours a night for one week has been shown to reduce a healthy insulin response by roughly 20% in otherwise healthy adults.³ Nighttime post-meal blood sugar levels impact sleep quality and, in turn, glucose regulation the following day.

Scrolling before bed does more than keep your mind busy. The blue light emitted by phone and tablet screens activates specialized photoreceptors in the eye that signal the brain to suppress melatonin, the hormone responsible for making you feel sleepy. When melatonin is delayed, so is everything that follows. Research comparing evening screen use to reading a printed book found that screen readers took longer to fall asleep, had significantly less REM sleep, and were measurably less alert the next morning, even after the same total time in bed.⁴ The cognitive stimulation from scrolling compounds this further, keeping the brain in an activated state when it should be winding down toward deep sleep.

Optimizing Deep Sleep Through Blood Sugar Balance

To truly enter a deep rest, blood sugar must remain balanced heading into bedtime. There are several dietary strategies to boost blood sugar support heading into sleep.. First, consuming carbohydrates with a lower glycemic index that are rich in fiber has been linked to better sleep quality (e.g., non-starchy vegetables versus starchy grains).⁵ Building meals around protein is also beneficial. Individuals characterized as good sleepers (those who sleep 7+ hours, have a sleep latency of less than 30 minutes, and a sleep efficiency greater than 85%) have been shown to have a higher dietary intake from protein and less from carbohydrates and fat compared to poor sleepers.⁶ In addition, avoiding food 3-4 hours before bedtime is beneficial, as dinner consumed closer to bedtime has been shown to affect how efficiently the body processes glucose during sleep.⁷ Alcohol can affect how the body manages blood sugar overnight. For some people, this contributes to disrupted sleep or waking in the early hours, even after what felt like a restful night to begin with. Lastly, avoiding caffeine late in the day is important, as caffeine, especially for those who are more sensitive to it, can elevate cortisol, impair sleep quality, and increase sleep latency.

How Can Reducose^® Support Sleep?

Reducose^® is a patented white mulberry leaf extract. Taken with a meal, Reducose^® helps maintain healthy insulin and post-meal blood glucose levels.* In clinical studies, post-meal glucose response was reduced by up to 42% and insulin response by up to 40% in healthy adults.* ^8,9

Recent research suggests Reducose^®, used as part of a formula, may support healthy sleep.* In a randomized, double-blind, cross-over trial, 750mg of Reducose^® was included in an evening supplement containing tryptophan and small amounts of zinc, magnesium, niacin, and vitamin B6. For 14 days, 43 adults (aged 25-50) who self-reported struggling with falling asleep either took the supplement or a placebo with their evening meals. After a reset period, they switched treatments. Taking the supplement led to a significant reduction in sleep onset latency by 14%, compared to baseline measurements.* ¹⁰

Those who took the supplement also had a significant reduction in post-meal glucose levels and lowered glucose variability during the night. Due to improved sleep and glycemic improvements, participants self-reported improved sleep quality and enhanced mood, friendliness, and energy the following day compared to controls.*¹⁰

Among individuals who self-reported poor sleep, taking an evening supplement containing Reducose^® was associated with a lower post-meal glycemic response and reduced nocturnal glucose variability.* The sleep study used Reducose^® as part of a multi-ingredient formula, but separate clinical research in healthy adults has shown reductions in post-meal blood sugar levels and insulin responses with Reducose^® alone.* ^8,9 Given that nocturnal glucose variability plays a central role in disrupted sleep, an ingredient that helps moderate the post-dinner glycemic response is a compelling option for sleep support formulas.* When post-dinner glucose response is moderated, the body may be better positioned for restful, uninterrupted sleep.*

For those looking to support sleep quality as part of an overall wellness approach, nocturnal blood sugar support is a factor worth considering. Reducose^® may help support a more stable post-dinner glucose response as part of a nighttime formula, which may in turn support the body's natural recovery processes.*

*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.

References:

1. Jauch-Chara, K., Hallschmid, M., Gais, S., Schmid, S. M., Oltmanns, K. M., Colmorgen, C., ... & Schultes, B. (2007). Hypoglycemia during sleep impairs consolidation of declarative memory in type 1 diabetic and healthy humans. Diabetes Care, 30(8), 2040–2045.

2. King, P., Kong, M. F., Parkin, H., Macdonald, I. A., & Tattersall, R. B. (1998). Well-being, cerebral function, and physical fatigue after nocturnal hypoglycemia in IDDM. Diabetes Care, 21(3), 341–345.

3. Buxton, O. M., Pavlova, M., Reid, E. W., Wang, W., Simonson, D. C., & Adler, G. K. (2010). Sleep restriction for 1 week reduces insulin sensitivity in healthy men. Diabetes, 59(9), 2126.

4. Chang, A. M., Aeschbach, D., Duffy, J. F., & Czeisler, C. A. (2014). Evening use of light-emitting eReaders negatively affects sleep, circadian timing, and next-morning alertness. Proceedings of the National Academy of Sciences, 112(4), 1232–1237.

5. St-Onge, M. P., Roberts, A., Shechter, A., & Choudhury, A. R. (2016). Fiber and saturated fat are associated with sleep arousals and slow wave sleep. Journal of Clinical Sleep Medicine, 12(1), 19–24.

6. Sutanto, C. N., Wang, M. X., Tan, D., & Kim, J. E. (2020). Association of sleep quality and macronutrient distribution: a systematic review and meta-regression. Nutrients, 12(1), 126.

7. Mantantzis, K., Campos, V., Darimont, C., & Martin, F. P. (2022). Effects of dietary carbohydrate profile on nocturnal metabolism, sleep, and wellbeing: a review. Frontiers in Public Health, 10, 931781.

8. Thondre PS, Lightowler H, Ahlstrom L, Gallagher A. Mulberry leaf extract improves glycaemic response and insulaemic response to sucrose in healthy subjects: results of a randomized, double blind, placebo-controlled study. Nutrition & metabolism. 2021 Dec;18(1):41.

9. Gheldof, N., Francey, C., Rytz, A., Egli, L., Delodder, F., Bovetto, L., ... & Darimont, C. (2022). Effect of different nutritional supplements on glucose response of complete meals in two crossover studies. Nutrients, 14(13), 2674.

10. Soon, C. S., Thota, R., Owen, L., Tian, L., Martin, F. P., Mantantzis, K., ... & Darimont, C. (2025). Mulberry leaf extract combined with tryptophan improves sleep and post wake mood in adults with sleep complaints — A randomized cross-over study. European Journal of Nutrition, 64(3), 124.