In any case, in order to sleep and earn money, you need to have a certain capital, or take care of a project or business that will generate profit without your intervention. In my opinion, the most suitable option is staking, but for this you need to first buy a sufficient amount of cryptocurrency, so that the profit is in the required amount.
Investment is the only way which can give you profit when you are sleeping because it increases in worth during favourable circumstances but the value of profit will depend on the amount you are using for investment.
If you are using money then your money will be increasing in value but it is not possible that without using money and working hard you will sleep and will become wealthy in just one night. In some cases you will just use your knowledge and money like investment in crypto and then leave it for appropriate timing then you will see that your invested amount has been increased if your coins remain profitable.
In life , Investment is most important part and everyone should learn how to invest the money . But many people invests due to his friend or his brother opinion. I think, man should research on the assets on which he should invest his money . Otherwise,his money will be waste and he will lose his investment, the formula is also applied for cryptocurrency because you invest your money with great knowledge and you invested 2 to 5 percent of your wealth,you will be successful in future. Always see the opportunities in the market and invest in it ,then you will get more profit and your portfolio will be high. The rule is also applied on stocks investment,bond investment and property investment. There should be great knowledge,if you want to invest in share market ,you can lose your all money if you invested on bad company. So always do research and then investment,then there are low chances of lose .
DYOR and keep improving your skills and knowledge about the investment that you will going to push thru, there are many opporunities around and with the right sets of knowledge you'll be able to manifest, I agree that once you already facilatate your skills in sorting out and finding the right information with what to support and where to invest then it will allow you to earn while sleeping, it's more on good practices and proper research to avoid losing your money and allowing your wealth to make extra and make it as compound to sustain your needs.