Driving lengthy commutes to and from work can SlumberPM eat into valuable sleeping time, and is not a good idea when you are feeling tired. If you do live a distance from your place of work then it might be an idea to try to carpool. Ie split the driving. If you do become drowsy when driving, then pull over and take a nap for 10 minutes or so, just to gather yourself before you continue on your way to or from work.
Before you can give yourself over to sleep, you must be warm in your bed. The comfort and reassurance of sleep will only envelop us when we are warm and relaxed. Having warm feet increases the temperature of the whole body, inviting sleep.
Hot water bottles are the quickest, most effective foot warmers there are, superior in many ways to microwavable socks which don't hold the heat for as long. Microwavable slippers have the same problem; they don't hold the heat and are much more expensive. The other downside of microwavable socks and microwavable slippers is that they will go soggy with repeated use now that isn't very suitable!