Social jet lag is the fatigue caused by a mismatch between our social and biological sleep clocks. In other words - our bodies want us to sleep at a certain time but our lifestyle doesn’t fit in with that.
We all have different circadian rhythms (‘sleep clocks’) that affect when we want to sleep. Referred to as chronotypes, you may be an early bird (‘a lark’), a night owl or somewhere in between. When we get to choose our wake and sleep hours we get the best rest, no matter what time we actually go to sleep. Unfortunately life gets in the way. Work, school, social lives - all interfere with our preferred chronotype. We force ourselves to go to bed or get up earlier on the days we have to. We stay up late or sleep in on days off. And this leads to a fatigue known as social jet lag - basically our bodies are in a different time zone.
Apart from feeling exhausted, social jet lag actually has an impact on our health. It’s not just the amount of sleep that is affected, social jet lag also changes how much quality sleep we get. Weight gain, heart disease, type 2 diabetes and depression are all linked with chronic sleep deprivation and social jet lag. People with social jet lag are also more likely to drink caffeine, be smokers, and drink more alcohol. It affects our mood, our memory, our coordination and our hormones. Our body is programmed to run by our circadian rhythms and constantly changing them is doing us harm and putting us at risk.
It is estimated that 2 in 3 of us experience at least one hour of social jetlag a week. 1 in 3 experience two hours or more – the same as flying from Hong Kong to Brisbane and back each week!
While the occasional sleep in is unlikely to do us harm - and in fact may be beneficial if you have a sleep debt to catch up on - having a regular sleep pattern is ideal. If you have the flexibility to fit your lifestyle around your sleep pattern - go for it! If you can study or start work later (or earlier if you’re a lark) this may be better than forcing yourself to get up earlier. Unfortunately this isn’t often possible.
So what can you do? The key is light. Filter out blue light at night or avoid screens altogether. Get up and go outside as soon as you can, or eat breakfast near a bright window. This helps get your circadian rhythm more aligned with the day. But keep in mind you’re best to keep this up on your days off if you want to be as healthy as you can. Find out more about how Candor can help with sleep here.
Wittmann M, Dinich J, Merrow M, Roenneberg T. Social jetlag: misalignment of biological and social time. Chronobiol Int. 2006;23(1-2):497-509. doi: 10.1080/07420520500545979. PMID: 16687322
Facer-Childs E, Middleton B, Skene D, Bagshaw A. Resetting the late timing of ‘night owls’ has a positive impact on mental health and performance. Sleep Med. 2019;60:236-247. doi:10.1016/j.sleep.2019.05.001
Forbush S, Fisseha E, Gallagher R et al. Sleep. 2017;40(suppl_1):A396-A397. doi:10.1093/sleepj/zsx050.1066