An internationally respected pioneer in circadian rhythm research, Prof Joseph Takahashi, of the United States, made that point in an interview on Friday.
He later gave a public lecture at the University of Otago, organised by the Otago physiology department, which focused on "The 24 hour clock in our DNA".
Often referred to as the "body clock", the circadian rhythm is the cycle that tells our bodies when to sleep and rise, and regulates many physiological processes.
Prof Takahashi is based at the University of Texas Southwestern Medical Centre and is an investigator at the Howard Hughes Medical Institute.
There was a growing realisation among researchers that maintaining a healthy weight was not only a matter of the kind and amount of what was eaten, but also when it was consumed, he said.
Some animal experiments showed that even healthy food eaten at the wrong time, such as when the rodent would normally be sleeping, had a more adverse effect on health than when food was eaten at the right time.
He urged greater awareness of health problems, including heightened diabetes risk, resulting from sleep deprivation and disrupted circadian rhythms.
Many people were facing growing problems with "circadian misalignment", a disruption to the body clock rhythm. The duration and quality of sleep made a "huge contribution" to human health.
Many shift workers became "progressively sleep deprived during the week" and at the weekend they tried to "recover from social jet lag", including by sleeping in.
He also warned about the risks to sleep posed by some forms of bright LED street lighting, and people using bright smartphone screens before trying to sleep.
His research group discovered the genetic basis for the mammalian circadian clock in 1994 and identified the clock gene in 1997.
Dr Alexander Tups, of the Otago physiology department, and a member of the Otago Centre of Neuroendocrinology, invited Prof Takahashi to Dunedin.
