Pulmonologist Joaquin Duran has settled the debate over sleep duration, stating that the ideal night of rest lasts between six and nine hours.
The specialist explained that human sleep is structured around recurring cycles, with healthy adults requiring between four and six complete cycles every night to fully recover.
His assessment was reported by the publication El Confidencial, which examined how biological rest functions and why sleep requirements differ from person to person.
According to Duran, sleep consists of several distinct phases that are each essential for the body to restore itself. When combined, these progressive stages form a single cycle that lasts approximately 90 minutes.
Because each cycle takes an hour and a half, completing the recommended four to six cycles adds up to a nightly rest of six to nine hours. Duran noted that the exact figure within that range depends on individual characteristics.
Sleep Cycles and Physical Recovery
In medical science, a sleep cycle represents the natural sequence through which the body moves between light sleep, deep slow-wave sleep, and rapid eye movement sleep, often known as REM sleep. During the deepest stages, tissues repair, muscles relax, and the immune system strengthens, while the brain processes memories and emotions during active dreaming phases.
Duran warned that this restorative process breaks down if the natural rhythm is interrupted. If the schedule is disturbed by health disorders such as sleep apnea, shallow sleep, or related issues, the rest remains incomplete and the body suffers severe strain.
As a pulmonologist, Duran treats conditions affecting the respiratory system, which are closely linked to sleep quality. Sleep apnea causes the airway to become repeatedly blocked during the night, triggering brief awakenings that prevent the sleeper from reaching or maintaining deep sleep.
Evening Screen Time and Healthy Habits
The advice follows earlier recommendations on sleep hygiene from psychologist Ksenia Gerasimova, who addressed common evening habits that prevent people from falling asleep on time.
Gerasimova advised people seeking better rest to stop browsing on mobile phones before bed. She recommended limiting evening screen time to between 20 and 40 minutes.
Electronic screens emit blue light that suppresses melatonin, the natural hormone that signals to the brain that it is time to sleep. Cutting down on digital devices in the late evening protects circadian rhythms, helping sleepers complete their required 90-minute cycles without unnecessary disruption.
