I usually sleep my laptop. After waking, the swap usage has increased.
The problem is that you've got 8G RAM. The swap file/partition WILL be used... and in fact, you might wish to increase your swap file/partition to 4G. Changing the
vm.swappiness parameter might change swap usage, but with 62% of RAM used, as in your example, you WANT it to swap.
With no swap file/partition, or with too little swap file/partition, understand that in the current example (100%-62%=)
38% of unused RAM is used a disk/file buffer/cache. With no/little swap, and RAM usage increasing, and disk/file butter/cache being reduced and reduced, and OOM (Out Of Memory) process trying its hardest to keep the machine running, it'll eventually run out of resources, and with no where to go, and it'll hang/crash the computer.