The natural rhythm of sleeping all night 😴 and at the same time helping to burn fat

This means:

“Getting regular, uninterrupted sleep may help your body maintain its natural sleep rhythm while also supporting healthy metabolism and weight management.”

Breakdown
“The natural rhythm of sleeping all night” = sleeping continuously and following a consistent sleep-wake schedule.
“At the same time” = suggests that sleep may provide another benefit.
“Helping to burn fat” = claims that healthy sleep can support the body’s metabolism and use of stored energy.
Tone

This is a sleep and weight-loss clickbait headline. It combines two attractive promises—sleeping better and burning fat—to encourage people to click.

A more accurate version:

“How healthy sleep habits may support better sleep and healthy weight management.”

Good-quality sleep is associated with metabolic and appetite regulation, but sleeping in a particular way isn’t a magic fat-burning method. Significant weight loss still depends largely on overall diet, physical activity, and energy balance.