You can leave a Lenox table lamp on overnight if the light bulb remains cool to the touch during long-term use. Low-wattage LED bulbs are best for this purpose, but other styles, such as CFlLs, also have low heat emissions. Bring your hand close to the bulb to check for heat after several consecutive hours of use before assessing whether it is safe to use all night.
Keep in mind that the lampshade that comes with the lamp must be designed for safety and fire resistance. Replacing this lampshade with a cheap paper or fabric lampshade from an untrusted source can increase the fire risk. For even greater safety, consider using a glass lampshade.