The recommended amount of time you should sleep every night is somewhere between 7 and 9 hours a night. Experts say that naps should be restricted to a maximum of 20 minutes per session so that you don’t feel completely lethargic and lazy after you wake up.
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But when it comes to sleep, we all know that it’s never a case of 'one size fits all.' Some people prefer to sleep less and take no naps during the day, while others could have two-hour long ‘siestas’ despite getting a full 10 hours of sleep at night.
The study
For years, nap-lovers have been criticised for being lazy or having bad sleeping habits, but the truth is far more complicated than simple behavioural choices. In fact, new research shows that some people are more genetically predisposed to sleeping more during the day than others.
Scientists at Massachusetts General Hospital analysed the genetic information of 452,633 using data stored in the UK Biobank. The authors said that the participants ‘were asked whether they nap during the day’ and they had to reply either ‘never or rarely’, ‘sometimes’, or ‘usually’. To strengthen their analysis, they monitored a group of participants to identify accurate sleep patterns.
It’s in your genes
Using this data, and with the help of other international institutes, they found that 123 ‘regions in the human genome were linked with daytime napping.’ They also noticed that there were ‘potential mechanisms’ that increased the need for napping—like disrupted sleep during the night and waking up early in the morning. Apart from these factors, and links to other health concerns, they observed that some people just generally needed more sleep than others.
Dr. Hassan Dashti, co-author of the study, said:
This tells us that daytime napping is biologically driven and not just an environmental or behavioural choice.
Iyas Douglas, a medical student at Harvard Medical School who is also a contributing author of the study, believes it could potentially be caused by a disturbance with orexin, a neuropeptide that regulates 'wakefulness.' He said:
This pathway is known to be involved in rare sleep disorders like narcolepsy, but our findings show that smaller perturbations in the pathway can explain why some people nap more than others.
