According to a report by The Times, they are indicators of one suffering from mood issues like bipolar disorder or neuroticism.
The Lancet Psychiatry reported people up that late were likely to rate themselves very lonely and not happy.
Some researchers believe modern life may be the reason for this trigger.
For the study, researchers measured body clock disruption on 91, 000 middle aged people using wearable monitors.
"These were people who have very poor sleep hygiene, people on their mobile phones at midnight checking Facebook or getting up to make a cup of tea in the middle of the night," author of the study paper Daniel Smith, from the University of Glasgow, is quoted as saying by The Times.
The team found one quarter of people had an abnormal pattern and were:
* 6% more likely to suffer from depression
* 11% more likely to have bipolar disorder
* Happiness levels were 9% lower
"Everyone who has ever stepped off a long-haul flight or had children knows that even a couple of nights’ poor sleep can be pretty bad for your mood and thinking ability... I don’t think it’s unreasonable to say this is another piece of evidence that might suggest we should all be more mindful of our natural rhythms of activity and rest," Professor Smith explained.