How does sleeping with the lights on hinder weight loss? Scientific analysis and improvement suggestions.

Sleeping with the lights on is a very bad sleep habit.

The human body has its own internal cycle, known as the biological clock. The biological clock governs a person's circadian rhythm, determining when to be awake and alert, and when to be tired and sleepy. It is because of the management of the biological clock that people don't wake up hungry at night, nor do they urinate as frequently as during the day.

The most important external factor affecting the body's circadian rhythm is that the body determines whether it is day or night by detecting light intensity. When the body encounters bright light at night, when it should be sleeping, the brain sends a "start a new day" signal, leading to a disruption of the circadian rhythm. Jet lag is a typical example of circadian rhythm disruption.

In fact, a research article published in the *American Journal of Epidemiology* found that women who habitually sleep with the lights on at night tend to be overweight and have larger waistlines than average. Prolonged light exposure at night inhibits the secretion of growth hormone, a hormone that promotes fat breakdown and is beneficial for weight loss. When its secretion is blocked, it affects weight loss results.

The secretion of many hormones in the human body fluctuates with the diurnal rhythm, but melatonin is undoubtedly the hormone most closely related to sleep. Produced by the pineal gland, melatonin influences signals from the hypothalamus. Melatonin typically begins to be secreted about two hours before sleep, inducing sleepiness and lowering body temperature to prepare for sleep. Melatonin is highly sensitive to light; even a dim nightlight can affect its secretion.

Besides regulating sleep, melatonin is also closely related to mood. People with insufficient melatonin secretion are more prone to depression, irritability, and emotional overeating. Melatonin is not only a hormone but also a powerful antioxidant, crucial for women's anti-aging and maintaining a healthy immune system.

Furthermore, sleeping with the lights on increases insulin resistance, and many people's obesity problems are related to insulin resistance.

The effects of sleeping with the lights on hormones and metabolism go far beyond this. Without good sleep quality, how can one achieve more efficient weight loss?