Large swap files?

Hi Guys,

Have a year old Air with 4GB RAM, and I use it only for some spreadsheets, surfing, PDF files and mail. My free space keeps getting smaller and get normal with a reboot only. Did some research and found that swap files take up over 6gb, but don't know what to do about it. Suggestions?

DVR-MacBook-Air-2:~ user$ ls -ael /private/var/vm
total 25165824
drwxr-xr-x 15 root wheel 510 Jun 10 02:59 .
drwxr-xr-x 30 root wheel 1020 Mar 15 10:14 ..
-rw------T 1 root wheel 4294967296 Jun 3 07:12 sleepimage
-rw------- 1 root wheel 67108864 Jun 6 07:49 swapfile0
-rw------- 1 root wheel 67108864 Jun 10 07:33 swapfile1
-rw------- 1 root wheel 1073741824 Jun 10 07:33 swapfile10
-rw------- 1 root wheel 1073741824 Jun 10 07:41 swapfile11
-rw------- 1 root wheel 134217728 Jun 10 07:33 swapfile2
-rw------- 1 root wheel 268435456 Jun 10 07:33 swapfile3
-rw------- 1 root wheel 536870912 Jun 10 07:33 swapfile4
-rw------- 1 root wheel 1073741824 Jun 10 07:33 swapfile5
-rw------- 1 root wheel 1073741824 Jun 10 07:33 swapfile6
-rw------- 1 root wheel 1073741824 Jun 10 07:33 swapfile7
-rw------- 1 root wheel 1073741824 Jun 10 07:33 swapfile8
-rw------- 1 root wheel 1073741824 Jun 10 07:33 swapfile9
DVR-MacBook-Air-2:~ user$