No, it’s not that kebab you ate on the way home from the pub that’s causing you to gain weight, but rather your 3am bedtime.
Well, that's the take-home from a study published in the journal Sleep on Friday, showing the later teenagers hit the hay, the more likely they were to gain weight over time.
Researcher Lauren Asarnow said the study, conducted by the University of California-Berkeley and Columbia University, was the world's first into the relationship between bedtimes and body-mass index.
"These results highlight adolescent bedtimes, not just total sleep time, as a potential target for weight management during the transition to adulthood,” Asarnow said in a statement.
Sleep Health Foundation sleep psychologist Dorothy Bruck told The Huffington Post Australia these findings indicated a third causal link between late nights and weight gain -- mental health.
“We know that people who have a later circadian rhythm, who go to bed later, have a higher chance of having mental health issues such as depression, so there could be a link there,” Bruck said.
Bruck also said these findings may encourage young people to consider the importance of sleep more seriously.
“A lot of young people are very concerned about their weight, so it might be an incentive for them to make sure they are in bed at a reasonable time,” she told HuffPost Australia.
“However, early bedtimes will be competing with other social things, going out with their friends, so it will be difficult."
These findings come as Aussies prepare to turn back the clock for daylight savings, which will end in the early hours of Sunday morning, making it more difficult snuggle down early.
Professor Bruck said the best way to re-adjust to the time change was to make sure your body got lots of natural light early in the morning.
“Morning light reduces levels of melatonin in the body, which means it will rise earlier in the evening making you more tired at night time,” she said.
She also said bringing forward your ‘buffer zone’, the time you wind down before bed, is important to ensure that once your head hits the pillow you can actually fall asleep.
Activities such as stretching, meditation, sex and reading can help you wind down, while #netflixandchill in bed is a surefire way to a poor night's sleep and a daylight savings hangover.
“Blue light from computer screens is a little bit different to watching TV, as it decreases melatonin in the body. You want your melatonin to rise up, to make you sleepy.”
According to Professer Bruck, downloading a program called ‘f lux’, which makes your computer emit light that mimics the time of day, can help alleviate this issue.