A naturopathic doctor's video explaining the viral phenomenon of the "second wind" and its effects on sleep hormones has gone viral, resonating with many night owls.

In the clip, Dr Kara explains that going to bed between 11 p.m. and 1 a.m. disrupts the natural balance of hormones - cortisol and melatonin - leading to poor sleep quality.

"If you go to bed between 11pm and 1am, you are doing a disservice to your hormones," she begins. "In the evening, cortisol should be at its absolute lowest because it needs to allow melatonin to be at its highest to put you in a deeper restorative sleep".

Cortisol and melatonin work in opposite ways, so if you push your body to go to bed past 11 p.m., you're causing a second, third, or even fourth cortisol spike.

"This spike prevents and suppresses melatonin's release," she explains. "The spike also causes a bout of hypoglycaemia in the middle of the night, forcing you to wake up a few hours later, so the best time to go to bed is 10:30pm to avoid the second spike and wake-up time around 6:30am".

Commenters felt seen by the clip, with one writing, "Me watching this at 11:30pm," and another saying, "Who's watching this going to sleep after 1am and waking up at 4am and haven't been back to sleep yet?"

Sleep expert Matthew Beard, CEO of A.H. Beard, told news.com.au that the so-called "second wind" is a real biological phenomenon.

"It's a natural surge of alertness that often happens in the evening, driven by our circadian rhythm," Beard told news.com.au.

"It's why you might suddenly feel wide awake when you're expecting to be winding down. Going to bed during this period can make it harder to fall asleep, which can delay your sleep cycles and reduce the overall quality of your rest."

According to Beard, for most adults, aiming to be in bed around 10 to 10:30 p.m. aligns best with the body's internal clock.

"Hitting this window supports deep and REM sleep cycles, which are critical for energy, focus, and overall health," he said.

But he stresses that an ideal bedtime isn't a one-size-fits-all prescription.

"Teenagers, for example, naturally feel alert later due to biological shifts in their circadian rhythm, while older adults often prefer earlier nights," Beard said.

"Lifestyle factors, work schedules, and whether you're a morning lark or night owl all play a role too in deciding the best bedtime for each person."

For those struggling to reset their routines, Beard recommends easing into earlier nights gradually.

"Start by moving your bedtime earlier in small steps - 15-20 minutes every few nights," he suggested.

"Reduce bright screens and blue light an hour before sleep, establish a relaxing pre-bed routine like reading or gentle stretching, and stick to consistent wake-up times. Avoiding caffeine or heavy meals late in the evening also helps your body adjust naturally."

It comes after a new study mapped five distinct "sleep profiles" that reveal how different brain patterns and emotions affect our rest.

Published in PLOS Biology, the study led by Sydney's Woolcock Institute examined data from 770 young adults to map connections between sleep, lifestyle and mental health using artificial intelligence.

The five categories include "poor sleepers," who struggle with anxiety and disrupted nights, "sleep-resilient" people, who sleep well despite attention or focus issues, "short sleepers," who rest less and experience irritability or memory lapses, "sleep-aid users," reliant on medication or supplements, and "disturbed sleepers," whose rest is affected by alcohol, dehydration or smoking.

Each type showed unique brain activity patterns, suggesting distinctive biological and emotional mechanisms behind their sleep quality.

Experts say these findings could help identify early signs of conditions like anxiety and depression, and tailor sleep treatments more effectively.

Doctor weighs in on 'second wind' phenomenon, and when you should go...