Others are kept up by chronic stress or insomnia and some have a disorder like sleep apnea.
“We habituate to adenosine, a brain chemical that induces sleep. So even though judgment and performance are impaired, we think we are performing just fine,” Wickwire added.
"The reality is, they are depriving their brains of a nutrient just as vital as food or water," he cautioned.
Warning signs are low energy, decreased sex drive, irritability, poor concentration and depressed mood.
Get eight hours of sleep at any cost to avoid such signs, Wickwire concluded.