The components are designed to run, and run. It will wear certain parts like fans and the screen out slightly quicker, but so long as you keep the insides clean from dust and dirt, and the temperature at a decent level (maybe with a separate laptop cooler) it should be quite happy!
I loften leave my old Toshiba laptop on for a couple of days at a time, and is still going strong, despite being about 6 years old! I have had to replace the battery, and the screen, but all quite cheap easy to fix parts. Just keep an eye on the temps (including power supply and battery) and you will be fine!
Hope this helps,
Regards,
K.