February 28, 2025, 2:50 pm | Read time: 5 minutes

Science has long assumed that persistent sleep disorders can promote the development of various diseases, including by promoting inflammation in the body. A recent study has investigated the connection responsible for this in more detail and revealed some alarming facts about the possible consequences of just one night of insufficient sleep.

Study on Sleep and Inflammation in the Body

The exact way in which sleep deprivation affects the immune system is not yet fully understood, according to the introduction to the study. However, it is assumed that chronic inflammation — which is promoted by too little sleep — plays a central role in the development of various diseases. In addition to cardiovascular diseases, these include diabetes and autoimmune diseases. The link between sleep deprivation, obesity, and systemic inflammation, in particular, is considered a key area of research.

Inflammation is a natural defense reaction of the body to harmful stimuli such as infections or injuries. FITBOOK explains in more detail here which different immune cells there are and how they work together. The current study focused specifically on subclasses of monocytes and how their distribution is affected by sleep deprivation. Both an increased and a decreased number of monocytes can indicate various diseases.³ The aim was to investigate the inflammatory readiness under the influence of sleep deprivation.

Procedure of the Study

The research team recruited the study participants in various ways. Some responded to flyers or social media campaigns; others were recommended. Out of a total of 350 volunteers, only 276 generally healthy adults were ultimately admitted as they met the requirements of the study. For example, people with impaired liver, cardiopulmonary and renal function, medically diagnosed diabetes, and sleep apnea, among other conditions, were excluded from the study, as were those with a history of severe coronary heart disease. In the end, only 237 subjects completed the examination.

The women and men were divided into three groups based on their body mass index(BMI). With a BMI of 18.5 to 24.9, they were placed in the normal weight group; a BMI between 25 and 29.9 was considered overweight. A BMI of 30 or more was regarded as obesity. For the purpose of data collection, the subjects were asked to wear special health technology wearables, called ActiGraph GT3X, day and night. The devices were used to measure physical activity and also provided information on the users’ sleep. The researchers, led by Dr. Fatema Al-Rashed, tested subjects’ blood samples for levels of monocytes and other markers of inflammation.

Results

The average sleep duration of the study participants was around 7.78 hours per night. This value is within the general recommendation of the recognized National Sleep Foundation. The sleep efficiency was 91.4 percent. This value indicates how much of the time spent in bed was actually slept.

When analyzing the measured differences between the BMI groups in more detail, the researchers found significantly poorer sleep efficiency in the obese study participants compared to those of normal weight. They interpreted this as impaired sleep quality. The quality of sleep was also lower in the overweight group, although not to the same extent. In addition, the researchers measured a significant increase in non-classical monocytes in the group of obese participants. They concluded that these values were associated with poorer sleep quality and higher inflammatory markers.

Even One Night with Too Little Sleep Promotes Inflammation

In a separate part of the study, five of the slim test subjects underwent 24 hours of sleep deprivation. As part of this, blood was taken from them. It was found that even this short-term sleep deprivation changed the profile of the monocytes — it was now similar to that of the obese participants. This underlines the role of sufficient healthy sleep in the regulation of inflammation, the authors explain in a press release.⁴

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Significance of the Findings and Limitations

Their study provides valuable insights into the relationship between sleep deprivation, obesity, and inflammation, the researchers emphasize. In the next step, they want to investigate the specific mechanisms that link the lack of good sleep to changes in the immune system and also find out whether special measures — such as sleep therapies or recommendations to use certain aids — can reverse the observed effects on the immune system.

However, the limitations of the study are also pointed out. As this was a cross-sectional study, it is difficult to prove definitive links between sleep quality and immune responses, including with regard to the influence of weight. Long-term studies would be necessary for a deeper understanding of the relationships. In addition, the number of participants was relatively small, which reduces the transferability of the results. Furthermore, the observations are based on measurement data. Although these were objective, there was a lack of reliable information on other habits of the test subjects — such as their diet, for which they had provided information themselves. This could have had an influence on their sleep and caused inflammation. The researchers are also concerned that the pure data excluded more subtle or subjectively perceived sleep disorders, which could also play a role.