Should cats be kept in at night?

Cats Protection recommends that you keep your cats in at night.  
The main reasons for this:
1. Increased risk of road traffic injuries/fatalities at night

Cats are natural hunters, making them more active at night time, and some studies show that more road traffic injuries happen at night.  According to studies by Pet Insurance companies, the findings were that approximately 78% of all road traffic accidents involving cats happen at night. It is not just busy roads that can cause cats to be injured or killed, but also quiet country roads that only have a few cars passing through which can catch a cat off guard. Therefore, we recommend keeping your cat indoors at night to protect them from the hazards of the roads. A reflective or fluorescent quick-release collar may help get them seen, particularly in the winter months when it gets dark earlier. However, collars themselves are not without risk, so ensure it fits properly on a regular basis. Two fingers should fit snugly between the collar and the cat’s neck and it should have a quick-release fitting to prevent your cat becoming ensnared or getting their leg trapped.
2. Risk of harm from other animals and humans
Cats can be injured through contact with other animals, such as other cats and wild animals.  There have also been numerous reportings of cats being killed by humans (many in the London area and recently in Welwyn Garden City - story here).  Keeping your cat in at night will help keep your cat safe.

If you decide to keep your cat in at night, you need to ensure that your cat's needs are met indoors:
If your cat is used to being active at night, it can become restless and stressed when kept in. If it is necessary to keep them indoors, an indoor environment should provide them with plenty of things to do - from toys and climbing frames to puzzle feeders.  Also, ensure they have access to a litter tray and water (not near to each other) when kept indoors overnight.

Cats are natural hunters and any time spent not doing this needs to be filled up with both exercise and mental stimulation - the best way to use up your cat's energy is to play with him.

There are lots of toys available in pet shops, or alternatively you can make your own. Ping pong balls, string, empty egg boxes with treats or some of their dry food allowance, and old plastic bottles make great items for playing with, as cats are mainly attracted to anything novelty or with movement. Change toys regularly to keep things interesting and provide catnip toys for catnip-loving felines.

It's no surprise that cats like to climb and hide inside things, so providing shelves, climbing frames and boxes are sure to keep them entertained. Cats also like scratching, so its a good idea to get a scratching post, in case he begins to use your sofa!
You may also wants to consider a 'catio' - a cat enclosure for your garden that is linked to the cat flap.  Here is an example of a very lovely catio - Google it for a variety of design ideas! Image result for catio
If your cat is used to being outdoors at night and you want to start keeping him in, you may find he becomes restless, but your cat will soon get used to the new routine (as long as you meet the cat's needs as detailed above).
Please note: A cat should never be locked out all night. Also, ensure that cats have access to shelter in the day time, either providing a kennel or access to a shed. Even simpler would be to put in a microchip cat flap which only lets cats in that have their chips programmed into the cat flap register.