What time should adults sleep for better health?

New Delhi : It is known that an adult requires seven to eight hours of good quality sleep and most people keep arguing that it is not relevant to timing. While it sounds comforting, the real life effects may differ.

Quality sleep has many benefits like it improves memory, promotes emotional stability and reboots cellular metabolism. But sleeping late at night, despite the fact you are sleeping for 7-8 hours, it may not result in the same positive manner.

The lockdown has made things worse; nearly 67 per cent of the people have been seen going to sleep after 11pm. Before lockdown, a 2018 study found that about 53 per cent of Indians sleep late at night after scrolling through social media, while 18 per cent revealed that work or finance-related issues kept them awake at night, as reported by Economic Times.

To make things clear and support the claims in many studies over the correct timing of sleep; here are some real life advices from the experts.

Dr Joy Desai, director, neurology, Jaslok Hospital and Research Centre, told indianexpress.com, "There is a master clock in the suprachiasmatic nucleus (SCN), which is a region of the brain in the hypothalamus. This is meant to sychronise with the clock in your other bodily systems. All biological functions have a circadian rhythm that is primarily determined by daylight — also known as Zeitgeber — that provides the setting for the biological clock."

The human brain is actually wired to sleep after three-and-a-half to four hours after sunset. So, if the sunset is between 6:30-7pm, you are actually wired to sleep by 10-10:30 pm, the doctor emphasised. When light levels drop, it stimulates the cells in the retina that signal the hypothalamus. There is a peptide called pituitary adenylate cyclase-activating peptide (PACAP) which makes the SCN signal to other body parts by secreting melatonin, a hormone that regulates the sleep-wake cycle. If you start sleeping late every night, the body stops making melatonin at the right time.

Melatonin production is supposed to start by 9 pm which then peaks by 1 am. But if you get into the practice of being awake and looking at the television screen or phone till late at night, over a period of time the brain stops making melatonin at the right time. If this starts in your youth, by the time you are older, you are unable to sleep even if you go to bed early, Dr Desai warned.

What happens when you sleep late at night?

Social jetlag is correlated with obesity. So, despite good diet and exercise, people experiencing social jetlag are at risk of becoming obese. That is because the peripheral clock in your other body systems are not in sync with the brain's clock, Dr Desai explained. The desynchronised system of energy metabolism negatively impact peptides in the body — leptine and ghreline — that determine our hunger and satiety. Sleep harmonises energy metabolism in the body. So, when you sleep late at night, it is likely to increase the risk of various disorders like diabetes, obesity, mood disorders and memory issues in older people.

What is the correct time to sleep?

As explained earlier, an adult must develop a habit of going to bed at 10:30 pm and wake up at 6:30 am.

"If you are waking up at 6:30 am, you should have breakfast by 7 am, which signals the body that the day has begun, thereby reinforcing the circadian rhythm. Again, when you exercise in the evening, you feel energetic for the next few hours which can delay sleep. So it is recommended that you exercise in the morning. If not, then you can exercise early evening," Dr Desai advised. "These are all secondary signals to the body that your daylight cycle is in sync," he added.