For Bryan Johnson, this is the most destructive belief in the world: ‘A single night…drops glucose stability by 30-40%’

"A single night of 4-5 hours of sleep reduces cognition by 20-40%, drops glucose stability by 30-40%..." listed out Johnson.

Bryan Johnson says the most destructive thing for health is lack of sleep

Bryan Johnson talks about the most destructive thing for health. (Source: Instagram/@bryanjohnson)

4 min readNew DelhiJan 3, 2026 03:57 PM IST First published on: Jan 3, 2026 at 03:57 PM IST

According to American biohacker Bryan Johnson, “sleep increases your odds of success,” and the most destructive belief in the world is that sleep deprivation produces better results. “A single night of 4-5 hours of sleep reduces cognition by 20-40%, drops glucose stability by 30-40%, increases accident risk by 400%, elevates inflammatory markers by 50-100% and impairs memory consolidation by 40-60%,” he mentioned in his latest Instagram post.

Is it true?

According to Dr Krishnasree K S, Associate Consultant – Department of Neurology, KIMSHEALTH Trivandrum, many people feel their productivity spikes after sleeping for a few hours, but that’s generally due to short-term adrenaline or genetic makeup. “If someone is stressed, excited, or highly motivated, their body may release adrenaline or cortisol, making them feel awake despite little sleep,” he told indianexpress.com. In fact, only a tiny percentage of people have a genetic mutation (in the DEC2 gene) that allows them to function well on 4–6 hours of sleep; these are true short sleepers, but they’re extremely uncommon.

Consistently sleeping only 4–5 hours might make you feel fine at times, but it usually harms focus, mood, metabolism, and long-term health.

Bryan Johnson talks about the most destructive thing for health

While there are true short sleepers, they’re extremely uncommon. (Source: Freepik)

How does lack of sleep impact us?

Lack of sleep affects more than just your energy levels. Here’s what it does to your body:

Memory, focus, and decision-making suffer, leading to slower reactions and lower productivity.
Less sleep is linked to high blood pressure, irregular heartbeats, and a higher risk of heart disease.
Sleep loss disrupts hormones that control hunger and stress, leading to overeating and weight gain.
Sleep deprivation reduces your body’s ability to fight infections, making you prone to frequent colds and illnesses.
Chronic lack of sleep is tied to anxiety, depression, and irritability, impacting mental well-being.

Quality sleep is much more than just the number of hours you sleep. “Quality sleep means avoiding frequent wakeups during the night. To function properly throughout the day, one needs at least 7 to 8 hours of quality sleep,” he said. Lifestyle choices such as high intake of caffeine and alcohol regularly and excessive screen time before bed are all major contributors to this phenomenon. In such cases, establishing a disciplined sleep schedule is crucial to improving your sleep.

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Dr Sunil Kumar K, Lead Consultant – Interventional Pulmonology at Aster CMI Hospital, Bangalore, suggested the following strategies to help you sleep better daily. “Make it a practice to go to bed 30 – 60 minutes earlier than usual. Wake up at the same time each day if possible,” he said, adding that if you have a habit of napping, add a short afternoon nap of 20 to 30 minutes if needed, but avoid late naps.

“Keep the bedroom dark, calm, and quiet, avoid caffeine after early afternoon, and reduce screens one hour before bed. Have lighter meals at night and have your dinner about 3-4 hours before hitting the bed. To stabilise your circadian rhythm, get morning sunlight to keep your body clock stable,” he concluded.

DISCLAIMER: This article is based on information from the public domain and/or the experts we spoke to. Always consult your health practitioner before starting any routine.