Being a so-called “night owl” affects a lot more than your bedtime.
Various studies suggest that habitually staying up late can wreak havoc on the body in various ways. Health complications that can stem from burning the midnight oil include:
1. Weight gain
Adults who restrict their sleep time by staying up late might be more susceptible to weight gain, according to the findings of a 2013 study.
Participants whose sleep was restricted to 4 to 8 a.m. consumed more calories overall compared with participants who slept from 10 p.m. to 8 a.m., the study found. Researchers attributed this difference to the first group’s consuming more meals late at night.
A 2011 study found that people who stay up late and sleep in also could be more susceptible to weight gain due to consuming extra calories during dinner and later at night.
Compared with participants who went to bed earlier and got up earlier, late sleepers also:
- Consumed 248 more calories per day. This was not deemed statistically significant, however.
- Consumed twice as much fast food.
- Consumed half as many fruits and vegetables.
- Drank more full-calorie sodas.
- Had a higher body mass index, a measure of weight that takes height into consideration.
Senior study author Phyllis Zee, a neurology professor at Northwestern University’s Feinberg School of Medicine, explained:
“Human circadian rhythms in sleep and metabolism are synchronized to the daily rotation of the Earth, so that when the sun goes down you are supposed to be sleeping, not eating.
“When sleep and eating are not aligned with the body’s internal clock, it can lead to changes in appetite and metabolism, which could lead to weight gain.”
For people who already have Type 2 diabetes, a 2013 study found that staying up late and sleeping in (as well as eating a big dinner) were associated with poor glycemic control, meaning poor control of blood glucose or blood sugar levels.
3. Muscle loss
A 2015 study of South Koreans found that among men who had an evening chronotype — which is an attribute reflecting your preferences in the timing of behaviors such as sleep — the health problems they were at a higher risk of developing included sarcopenia, a condition in which the body gradually loses muscle mass.
Study author Dr. Nan Hee Kim, of Korea University College of Medicine, said of night owls’ increased risk for such health problems:
“This could be caused by night owls’ tendency to have poorer sleep quality and to engage in unhealthy behaviors like smoking, late-night eating and [living] a sedentary lifestyle.”
4. Metabolic syndrome
Women who had an evening chronotype had more belly fat and were at an increased risk of developing metabolic syndrome, the same South Korean study found.
The Mayo Clinic defines metabolic syndrome as a cluster of conditions that occur together and increase the risk of heart disease, stroke and diabetes. Those symptoms include:
- Increased blood pressure
- High blood sugar level
- Excess body fat around the waist
- Abnormal cholesterol levels
5. Pregnancy challenges
A 2014 study concluded that darkness at nighttime is critical to the health of developing fetuses and to the reproductive health of women who are trying to get pregnant.
Exposure to light during the night suppresses women’s production of melatonin, which could deprive the fetal brain of enough of the hormone needed to regulate its biological clock, the study found.
Melatonin, which is secreted by the brain in response to darkness, also protects women’s eggs from what scientists call oxidative stress, which is also referred to as free-radical damage.
Study researcher Russel J. Reiter, a cellular biology professor at the University of Texas Health Science Center, explained to Live Science:
“We have evolved for 4 million years with a regular light-dark cycle that regulates circadian rhythms [biological clock]. We have corrupted this with the development of artificial light …
“There is a biological price to pay for disturbing the light.”
Reiter recommended that women who are trying to get pregnant have at least eight hours of complete darkness at night and keep those hours regular from day to day.
For more help getting sounder sleep, be sure to check out “16 Affordable Ways to Ensure You Sleep Like a Baby.”
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