Why do we get sleepy? Doctor explains

A video from Nonthaburi, Thailand circulated online showing a motorcycle taxi passenger briefly falling off a moving motorcycle after appearing to doze off.

According to Kuya Kim’s report on “24 Oras,” Friday, the man stood up moments later and continued his trip, saying he had simply fallen asleep.

While the incident ended without injury, it sparked curiosity about a familiar experience many people encounter daily: feeling suddenly sleepy.

Per Kuya Kim, sleepiness is largely influenced by the body’s internal clock, known as the circadian rhythm, which regulates when the body feels alert and when it is ready to rest.

“May oras kung kailan nag-i-increase ‘yung ating serotonin o melatonin na tinatawag natin na siyang nagpa-facilitate ng sleep. Actually, 9 p.m., 10 p.m., nagsi-start na mag-increase ‘yung ating serotonin levels. So, diyan talaga medyo inaantok na tayo, ‘no? Kaya kung hindi natin tinry i-sleep, the next day, ‘yung energy level natin down, kaya aantukin po tayo,” said Dr. Cheridine Oro-Josef, a geriatric and family medicine specialist. 

Another cause of sleepiness is the buildup of adenosine, a chemical in the brain that accumulates while a person is awake.

The longer one stays awake, the stronger the urge to sleep, with proper rest being the only way to reduce adenosine levels.

People may also feel sleepy after eating.

“‘Pag kumakain po kasi tayo, mag-i-increase ‘yung tinatawag nating glucose levels or sugar sa ating katawan. In short po, nandun ‘yung focus ng katawan natin, ang metabolism. So, ‘yung ating brain po natin at ‘yung ating organs, kalma lang muna siya at tapos pagtaas ng sugar po sa ating katawan, medyo inaantok po tayo,” Dr. Oro-Josef said.

She stressed that sleep plays a vital role in our lives.

“Napakahalaga ng tulog because when we are sleeping, that's when our body repairs. So, sa mga bata po, mas marami ang kailangan. Tapos habang tumatanda po tayo, umiikli po ‘yung tulog natin. So, 'pag tayo ay adults, we need around six or seven to nine hours of sleep,” she said.

—Carby Rose Basina/CDC, GMA Integrated News