`Night owls` more prone to weight gain

Staying up late could be associated with weight gain in teenagers, according to a study.


They discovered that for every hour of sleep they lost, they gained around 2.1 points of Body Mass Index.

A summary of the report said: “The aim of the current study was to examine the longitudinal relationship between bedtimes and body mass index (BMI) from adolescence to adulthood in a nationally representative sample”.

However, the relationship between bedtime and BMI was significantly reduced with the inclusion of fast food consumption.

“The results highlight adolescent bed times, not just total sleep time, as a potential target for weight management during the transition to adulthood”, said Lauren Asarnow, lead author and doctoral student in University of California-Berkeley.

The study incorporated three waves of data from the National Longitudinal Study of Adolescent Health between 1994 and 2009, with the youngest participants aged 12 and the eldest 32. BMI is one of the most common measurement tools of weight gain and obesity and is determined by comparing the person’s actual weight to height. The bedtimes were self-reported while the BMI was identified by the researchers.

In addition to Asarnow, co-authors on the study are Allison Harvey at UC Berkeley and Eleanor McGlinchey at Columbia University. Circadian cycles and sleep were self-reported and height and weight were measured by researchers to calculate BMI.

The study focused on three time periods, the onset of puberty, the college-age years and young adulthood.

The findings reveal that when it comes to managing weight, sleep is important. Scientists have found that teens and adults who go to bed late on weeknights are more likely to gain weight than their peers who go to bed earlier in the evening. The University of California research has been done with the adolescents reporting what time they go to sleep and the researchers computing their respective BMI’s.


Teens need a little more than nine hours of sleep a night, according to the American Academy of Sleep Medicine.

A new study finds a link between going to bed late and weight gain