A new study has found that individuals who prefer staying up late are more likely to develop type 2 diabetes.
After considering all the demographic and lifestyle factors, it was discovered that individuals who have a habit of sleeping late and waking up late are 19% more likely to have type 2 diabetes than those who go to bed and wake up early.
Researchers have identified different chronotypes based on the time of day an individual naturally gravitates towards. Individuals who typically wake up early and prefer the morning hours are called “morning people”. In contrast, those who prefer the evening and night hours are labelled “evening people”.
For this study, 63,676 nurses aged 45 to 62 were enrolled. Each nurse completed a questionnaire biennially from 2009 to 2017, and none of the participants had a pre-existing history of cancer, cardiovascular disease, or diabetes.
Among the participants, 11% were categorised as "definite evening" chronotypes, while 35% identified as "definite morning" chronotypes.
The researchers also examined a middle-ground chronotype for individuals who did not strongly identify with the two other chronotypes.
People who prefer to stay up late were 54% more likely to engage in unhealthy habits, such as smoking, not getting enough sleep, eating unhealthy foods, and being overweight.
After accounting for socioeconomic factors, shift work, family history of diabetes, and various lifestyle habits — especially a high BMI and lack of physical activity — the risk of diabetes associated with an evening chronotype was still considerably higher at 72%. This indicates that the factors mentioned, rather than the chronotype itself, are likely the primary contributors to the elevated incidence of diabetes.
Does chronotype reflect the clustering of lifestyle and other factors, or is it a causal risk factor?
For instance, students with heavy responsibilities and many tasks can be most active and alert during the evening. This can lead to feelings of distress, reduced sleep, and unhealthy habits. Additionally, these students may struggle with feeling partially depressed.
If the students' circumstances change, they may adopt a more morning-oriented chronotype.
Life events or job roles could act as a source of correlation between chronotype and lifestyle.
Associate professor of metabolism and endocrinology at Rutgers University, each person's chronotype will likely be unique.
Generally, the practical range of hours to work is from the morning to early afternoon, mid-morning to early evening, and late afternoon.
It helps align the body's natural rhythm with the clock, which dictates when people should go to work, take breaks, etc.
Morning people are generally more productive about five hours after they wake up, whereas evening people may need up to 10-12 hours before they reach their peak performance.
The reasons why evening chronotypes tend to prefer certain behaviours remain largely unknown.
If individuals consistently engage in activities such as sleeping in, being physically active, and eating meals later than usual, their bodies may become accustomed to these patterns. This can lead to nutrient imbalance and an increased likelihood of obesity.
The study revealed that evening types have an array of risks not experienced by morning types, including raised hypertension and pulse rate during everyday activities and physical exertion, as well as reduced fat utilisation for energy.
This cycle increases the risk of obesity, heart disease, and diabetes. Eating earlier in the day and avoiding late at night is essential to break this cycle.
He noted that some people refer to the difference between the amount of sleep they need or want and their wake-up time as “social jet lag.”
As a result of stress, the body activates the hypothalamic-pituitary-adrenal axis, increasing neurological activity that encourages cravings. Later in the day, people may feel an urge for sweet/fatty foods or cigarettes, which align with the neural circuitry and can result in a pleasurable feeling when those desires are fulfilled.
The authors may have been measuring factors associated with lifestyle - such as psychological factors and type of work - that could have influenced the results rather than the direct effects of chronotype on diabetes.
Light is a primary influence on the body's central nervous system, and activities such as eating and exercise impact peripheral clocks, such as those found in the muscles, liver, intestines, and heart. To adjust one's chronotype, one should consider stimuli that could help one's body to have a healthier rhythm.
To transition from an evening chronotype to a morning person, waking up earlier when the sun is still out is helpful; eating breakfast and moving around more in the morning is helpful. Additionally, one should avoid eating and physical activity at night, dim the lights earlier, and aim to go to bed 15-30 minutes earlier.
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