When Stanford University medical student Tarub Mabud, 24, gets together with his fellow students, they never talk about how hard they study or the challenges they face with their course work.
"It's an unwritten rule, when you hang with med school friends, you don't talk about med school," he said.
It has become part of the school culture for students to pretend to be gliding effortlessly through their courses, when they are actually paddling furiously to stay afloat.
A term has even been coined for this behaviour: Stanford Duck Syndrome.
While the syndrome is not a proven medical condition, the pressure to keep up appearances could cause students to feel added stress and, in extreme cases, develop mental health issues such as depression and anxiety, psychologists and counsellors told The Sunday Times.
Stress in elite American universities, especially exacerbated by behaviour like the Stanford Duck Syndrome, has come under the microscope in recent weeks after Singaporean student Ouyang Xiangyu, 26, was charged with four counts of poisoning her lab mates at Stanford.
She told police that she had been to see a counsellor and psychiatrist last year, and that she was suffering from depression, stress and insomnia.
At the University of Pennsylvania (U Penn), a 19-year-old freshman committed suicide last year, and reports said her death was linked to the stress of having to maintain good grades. In February this year, her university, which launched a task force last year after two consecutive suicides, released a report which recommended addressing a perceived perfectionist culture among students.
"Such perceptions may lead to pressures to succeed both academically and socially, that may be unrealistic and lead to feelings of being overwhelmed," said the report.
Students have also identified a phenomenon similar to the Stanford Duck Syndrome. Those with "Penn Face" put on a perfect front to hide any emotions - be it stress or sadness - that they might feel.
But Mr Manud, the medical student who studied at U Penn before heading to Stanford in California, on the west coast, said he did not feel the pressure to keep up appearances on the east coast.
"On the east coast, it's a point of pride to not be sleeping - you're a badass. Here, it's different... There are times when people are going to feel stressed by work but have to keep up a facade."
Some students believe the Californian sunshine and the image of students wearing T-shirts and shorts make everyone feel like they should be calm and relaxed all the time.
Said Ms Rachel Peters, a physical therapist who graduated from Stanford in 1997 and still works on campus: "You always see people in their bikinis on the lawn. They are lounging in their bathing suits, but they are actually studying."
While there are no studies to prove it, Vanderbilt University professor of psychology Steven Hollon said he "wouldn't be surprised" by the east coast-west coast divide. "It would certainly fit the ambience," he said.
But "having to put up the image of perfection is just one more source of stress on top of the work load", said Mr Kevin Kruger, president of Naspa, an association for student affairs administrators in higher education.
Across the United States, an increasing number of college students are reporting severe mental health issues.
Of more than 200 counselling centre directors who were surveyed in the National Survey of College Counselling Centres, 94 per cent said recent trends pointing to a greater number of students with severe psychological problems are apparent on their campuses. The centres also reported that 26 per cent of students were on psychiatric medication last year, up from 17 per cent in 2000.
Many students "do not handle stress well", said Ms Amy Lenhart, president-elect of the American College Counselling Association (ACCA).
Part of it has to do with the different parenting styles that have emerged, she added.
There are "helicopter parents" who hover excessively around their children tending to their every need, and "trophy kids" - a term used to describe the generation of children unaccustomed to failure - receiving a trophy even for participating in an event.
"They don't have the resilience and coping skills that previous generations have," said Mr Kruger.
"There is also pressure to get a good job because of the increase in tuition and student debt, which has added to the level of stress among students," he added.
A survey by the American College Health Association covering nearly 80,000 students and released last year showed that in the previous 12 months, 86 per cent of respondents felt overwhelmed, 54 per cent felt overwhelming anxiety and about 32 per cent were so depressed that they found it difficult to function.
Mr Rusty Selix, executive director of policy and advocacy at the Mental Health Association in California, said stress is a major cause of depression and anxiety.
"For busy graduate students, not getting enough sleep in itself can cause depression and anxiety," he said.
Another stress-inducing behavioural pattern that counsellors, psychologists and students raised is the "imposter syndrome", a phenomenon found both in an academic and professional setting.
It is a feeling of inadequacy often felt by bright, successful people, who believe they managed to fool others into thinking they are more intelligent than they believe themselves to be. As a result, they often fear being "found out".
Said Mr Francisco Gimenez, 28, a biomedical informatics graduate student at Stanford: "It was talked about a lot in the first year. You feel you're not good enough, seeing everyone else doing amazing things."
"Many feel like they do not belong, or they are not worthy, especially those in elite schools," added Mr Kruger.
ACCA's Ms Lenhart said this might be more pronounced now because of social media, where young people are "constantly being evaluated by their peers and they feel like they are under a microscope".
But students should never feel like they have nowhere to turn to.
Ms Lenhart said schools have outreach programmes to make sure students know of the counselling services available, and there is also the National Depression Screening Day, which is an opportunity for students to connect with counsellors for treatment.
A therapist can help students recognise negative thought processes and encourage them not to isolate themselves.
"They need to know feelings of depression are real - it is not something just in their heads," said Ms Lenhart.