What is the most common or correct spelling of "zzzzz"?
(1) zzzzz (5 letters)
(2) zzzz (4 letters)
(3) zzz (3 letters)
My question stems from when I first wrote it as "zzzzz" (5 letters) in an English text, but a friend told me it should have been written as "zzzz" (4 letters) so I decided to ask here.
More confusion arises from the following source because Susan Ince, the journalist, uses "zzz" (3 letters):
People who get too little sleep (six hours or less a night), plus have poor-quality rest, face a 65% higher risk of heart disease, a Dutch study of 20,400 people found. So take your zzz's seriously. Tell your doctor if you're having trouble sleeping or if you're waking up without feeling refreshed. And adopt good sleep hygiene — no caffeine after lunch, regular bedtimes and wake-up times, plenty of exercise in the early part of the day, no television or computer in bed — to help you get the rest your heart needs. (For more tips, read 25 Ways to Sleep Better Tonight.)
Before that I had checked it out on some online English dictionary and Google search but I wasn't able to clear it out.