Hitchhiking at night
Hitchhiking at night is definitely not as easy as during daylight. But it's still possible, depending on the situation and location.
For your safety always make sure that you are properly visible. At night drivers might not notice you. Consider wearing a fluorescent vest and using a torch.
Sometimes, especially but not exclusively at night, drivers will pick up a hitchhiker because they are tired and sleepy, but must get to their destination on time. Make sure you never fall asleep in someone's car if you are suspecting this might be the case. Even if you can't find a conversation topic, stay alert. If you have a driving license you might indicate your driver of this fact. In some cases he or she will be happy to let you drive.
To enhance your visibility, and therefore also your chance for a ride, wear a fluorescent vest or jacket. You can buy these in any bigger gas station, especially in those located on motorways. They can be relatively expensive in these places though (they can ask up to 4 euro for one), but if you buy one in a regular supermarket, you'll find them for 1 euro. If you don't have a vest or jacket, try to lay hands on any kind of fluorescent of reflective material; reflective strips that bikers use for instance. Apart that it helps for visibility; it also looks more "professional" and trustworthy. Drivers tend to trust you more, because if you'd be a maniac killer on the loose or an escaped convict or something, you wouldn't wear anything that draws attention, right? In some countries in Europe, like France, there are laws that force you to wear a fluorescent vest. However in normal circumstances the police won't bother to stop.
Some hitchhikers also use flash or blinking lights to draw the attention of drivers. This can work rather effectively. When done in the right way, that means to start using the flash when an approaching car is about five seconds away, most drivers drop their speed for example from 80 to 40 kmh. They are very attentive at that moment and especially keen on getting to know if they will be obliged to stop (by police for example). When done at the very right moment, a decided gesture will bring some of those drivers to stop. The technique has been described in detail on this page of VHHC.
In any case, try to stand in a well-lit place, but handy remembering that for some people, the image of a persons (especially a stranger's) head lit from directly above or below can cast an evil looking shadow around the eyes. Traffic lights could also be OK. If you are two hitchhikers and one person can use a lamp to light up the other hitchhiker. If you're alone you have to improvise a little, but it usually works much better with light.
When hitching in a lighted spot such as a major junction or the edge of the city, unless you are exactly sure where the driver offering a ride is heading, never ever accept rides to "a junction some kilometres down the road". However tempting it may be to get in a vehicle which will make you closer to your destination, you may very well end up in some fairly dark small junction where a narrow village road branches off the motorway and where you will likely spend hours until someone even dares to stop (or realise that there is a desperate hitchhiker waiting before it's too late to stop). Be patient, don't leave your well-lit major junction, and accept rides only to other well-lit major junctions or towns and cities.
Also, it must be said that hitchhiking at night is slightly less safe than during the day. The obvious reason is that you are less visable which effect roadsafety. But also that whenever something happens it is less likely to be seen by people arround you, so you are less likely to receive help. In adition, the percentage of drunk drivers or extremely tired (dangerous) drivers is higher during the night. And finally, from personal experience, you are more likely to be tired yourself which will affect your awereness.