For the past month or so, Ms Sarah Chew, 27, had been waking up every hour during the night and struggling to sleep right through till the next morning.
Nine out of 10 times, insomnia is a symptom of deeper underlying mental health issues
"I would look at the clock on my handphone, watching every minute crawling by and wondering how many more hours I had left to sleep before waking up for work," said Ms Chew, who lives with her husband in a Punggol flat.
The lack of quality sleep left her feeling sleepy during the day, she added. The civil servant, who used to sleep regularly at 10.30pm and wake up at 6.30am before the circuit breaker period started early last month, sought help from a clinical psychologist via a video conference about two weeks ago for her sleeping troubles.
After following a sleep routine established by the psychologist for a week, Ms Chew no longer wakes up in the middle of the night.
Fewer social interactions, not needing to commute or go for meetings and not being able to visit her parents on weeknights - those were changes in her routine that she thinks led to the sleeplessness.
"The lack of activity left me with a lot of energy at the end of the day," said Ms Chew, who has been working from home during this period.
Ms Chew is among those whose sleeping patterns have been disrupted by the circuit breaker measures. While clinics and hospitals said there has been no increase in the number of patients seeking help for sleep-related issues, doctors here pointed out that it could be a growing problem that has gone under the radar so far.
Dr Lim Boon Leng, a psychiatrist at Gleneagles Medical Centre, said that because his clinic is now seeing only patients with urgent medical needs during the circuit breaker, the number of patients seeking help for sleep-related issues has decreased.
Nevertheless, existing patients have complained of sleep issues more than before, said Dr Lim, who believes that there are many more with sleep difficulties not stepping forward.
"Covid-19 is a life-threatening illness and many are afraid of being infected or that their loved ones may get the illness."
"The pandemic has also dragged on with no end in sight, causing many to feel tired of the continued bombardment of bad news in the media and uncertainties over the future."
These factors, coupled with worries about financial security and feelings of isolation arising from social distancing measures, could also be keeping people up at night, said Dr Lim, adding that insomnia could also be a sign of a larger issue.
"Nine out of 10 times, insomnia is a symptom of deeper underlying mental health issues."
Those vulnerable to psychiatric conditions - such as having genetic predisposition, personality issues and poor social support - are more likely to lapse into mental health illnesses, with insomnia as one of the conditions, he added.
Associate Professor Joshua Gooley in the neuroscience and behavioural disorders programme at Duke-NUS Medical School agreed that new sources of stress, anxiety and rumination can be drivers of short-term insomnia.
"During periods of uncertainty like the Covid-19 pandemic, it can be difficult for the mind to 'shut down' when thinking about safety, money matters and family relationships."
Dr Sin Gwen Li, senior consultant at the department of psychiatry at Singapore General Hospital (SGH), said that sleep can also be affected during this period now that people are no longer going to work and school.
She added: "Many parents have to grapple with home-based learning and young children's needs in the day, and thus are forced to work only after the children have gone to bed.
"The divide between work time and play time also becomes less demarcated as people work late, such as attending video conferences after office hours."
Dr Sin added that the physical exertion of leaving the house to travel to work, get meals, and go out for leisure activities can be quite significant even for people who do not exercise regularly. The reduction in these activities can affect one's ability to have good quality sleep, she said.
While some have trouble sleeping at night, others are having late nights by choice, spending the witching hours playing video games and watching dramas instead.
Ms Yu Hui Xin, 21, stays up till 5am or 6am every day to play online games with her friends. The second-year accountancy student from Nanyang Technological University said that before the circuit breaker started, she made an effort to sleep earlier to prepare herself for classes the next day.
"Now that I know the next day I can wake up late, I don't mind sleeping later."
Ms Yu said that sometimes, after she has turned off the computer, she is unable to fall asleep till an hour after.
"Usually after a social event - even though in this case it is virtual - I need some time alone by myself. So I will think about stuff for about an hour before going to sleep."
Dr Lee Yeow Hian, consultant chest and sleep physician at Mount Elizabeth Novena Hospital, said people like Ms Yu may experience insomnia resulting from over-stimulation if they go to bed immediately after playing games or watching a drama series.
He added that they may have difficulties re-adjusting to a normal schedule once work or school life returns to normal.
Health experts warn of the adverse effect that long-term sleep deprivation can have on other aspects of health. A handful pointed out that short sleep is linked with higher risks for other illnesses such as diabetes, cardiovascular diseases and various kinds of cancer.
Long-term sleep deprivation may also lead to reduced immunity, making the body more prone to catching respiratory infections, said SGH's Dr Sin, who added that sleep is an important time for the body to "heal, grow, eliminate waste products, and replenish energy stores".
Assistant Professor June Lo at the National University of Singapore's Yong Loo Lin School of Medicine said that one way to sleep better is to reduce one's usage of smartphones and electronic devices during the circuit breaker.
This is because blue light emitted from the devices has been found to suppress the secretion of melatonin, or the sleep hormone, she added.
"The games we play and the movies and dramas we watch may also be so stimulating that we become cognitively aroused and have problems falling asleep.
"Because of this, we should stop using our electronic devices at least one hour before we go to bed."