You can indeed earn money while you're sleeping and that money is derived from passive income sources which means little to no work involved to keep the money flowing.
Some ideas to make passive income and money while you sleep are.
Investing.
Investing in things such as stocks and bonds can earn you money while you sleep if you know a lot of about investing.
If you can invest in the right stocks and you know what you're doing you can make a great deal of money dealing in and investing in stocks and the stock market.
Invest in Real Estate.
Investing in Real Estate is another way of making money while you sleep or while not doing much at all.
You can buy homes and pay others to market them and sell them for a profit or you can buy cheap homes that need renovations and hire others to do the renovations and then hire a Real Estate agent to market and sell the homes for you for a profit.
Many people make good income buying and flipping homes for a profit.
Another way you can make money investing in Real Estate is to rent out homes that you buy and you can hire a property manager to take care of the property, deal with tenants, advertise the rental homes and take the rental payments.
Start A Blog and make money while you sleep.
Starting a blog can also eventually earn you a passive income while you sleep but you do need to put in some effort in the beginning to setup the blog and write and publish stellar content that will get ranked high in the search engines.
You can also hire out the writing of the content to content writers and pay them to do the work of writing the content but you need to make sure that the content they're writing is not stolen and is original and of high quality.
You need content that gets a lot of Google Searches and other searches from other search engines.
The more searches a keyword gets the more traffic your blog can get and in turn you'll make more money from that traffic through Adsense, Media.net E Books, Affiliate programs or even selling your own advertising space once you have the traffic.
A blog will need a minimum of 100,000 monthly unique visitors before you make at least a part time income from Adsense or other ads so you need to be patient and work hard in the beginning to gain that traffic.
After at least 6 to 7 years of hard work blogging you should see some good income from your blog as long as you're doing things right and writing content that gets high searches.
You can use semrush or google ads keyword planner to research keywords that get lots of search traffic.