Sleep is necessary for your body and mind to function properly, and I would not recommend, at all, to change that. Sacrificing sleep in exchange for more hours to work will not necessarily make you more productive. Productivity is defined as the amount of work you can get done per unit of time. I'd suggest researching ways in which you can increase your productivity in your current schedule. Depending on what you're doing, you can probably get more value for your time by adopting a new technique or changing the way you do things. Automate tasks that take up too much of your time and provide little value, like sending emails. Use programs to handle calculations for you. If you're using Excel, VBA is a blessing in disguise once you get past the learning phase, for example. Or, if you're programming, use programs that generate code for you, like Copilot.
Moreover, without proper sleep, even if you have 20 hours a day to work, chances are you will not get much done, as fatigue might set in. Long term effects of sleep deprivation are also extremely serious. As a last resort, and if you really, REALLY, want to change your sleep schedule in order to increase productivity, research polyphasic sleep. There is only anecdotal evidence supporting it. Some people have an easier time with it, but for most of us, one chunk of 8 hours is all we need to be fresh.
On a side note, don't neglect your health and overwork yourself. Call me lazy, but I've had my chance to work 10-12 hours a day, and it is not pretty at all, even sitting all day becomes a nightmare. Some people can handle the workload, but 20 hours a day is really a lot. Hope this helps.