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

This means:

“Getting enough uninterrupted sleep and maintaining a healthy sleep routine may also support your body’s metabolism and ability to manage body weight.”

Breakdown
“The natural rhythm of sleeping all night” = sleeping continuously and following a consistent sleep-wake schedule.
“At the same time” = suggests that sleep provides another benefit beyond rest.
“Helping to burn fat” = claims that good sleep may help the body use energy efficiently and support fat/weight management.
Tone

This is a sleep-and-weight-loss clickbait headline. It combines two appealing promises—sleep better and burn fat—to attract attention.

A more accurate version:

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

Good sleep is important for hormones involved in appetite, metabolism, and energy regulation, but sleeping alone isn’t a guaranteed fat-burning method or substitute for an overall healthy diet and physical activity.