For starters, NOT all investigations are done at night, under the cover of darkness! It is true that paranormal activity can and will take place at all hours of the day. In fact, I have personally had more experiences during daylight hours in well lit locations. However, in order to maximize investigation time, a good investigator is going to look at the reports and talk to the client. Sometimes, requesting the client keep a log book or journal of suspected activity over a period of time is implemented. If there is a pattern emerging showing that the activity is most frequent during the day, then a daytime investigation will most likely yield the best results. Similarly, if there is activity being seen or witnessed under certain circumstances, such as only with the lights on, then a recreation of the environment will also be likely to yield the best results and provide the right conditions to try to rule out any non-paranormal causes. That environment can be changed, or investigations can take place over different times of day, and through different seasons, weather, etc., to further help rule out and find causes for suspected paranormal activity. This would be the ideal case scenario.
However, as investigators, we often find that obstacles and limitations prevent such ideal case scenarios. One such limitation is a direct cause as to why so many investigations actually DO take place at night!
Ghost hunting and/or paranormal investigation is not a paid endeavor and is a pretty expensive hobby. Since most of the population is not independently wealthy, many of us have to work, not only to finance our pursuit of the paranormal, but to provide for our own families. And, in this society, most of us work during the daylight hours, leaving night the best time to investigate. Obviously, our clients are in a similar boat; clients of private residence cases also need to work, go to school, and partake in normal everyday activities. Evening going into night is sometimes the only time THEY can find time in their schedules to have come in.
And while residentials can offer a little flexibility, you're less likely to find that flexibility when dealing with public locations. Popular places to investigate, such as restaurants, libraries, historical locations and other public establishments, have to deal with customers/visitors during the day. Most of the time, investigations are only available after hours...hence, after dark, which is a GOOD thing: investigations require as a controlled environment as possible, something which cannot occur when visitors are making their rounds. In addition, not all public locations want the publicity of a possible haunting; the night offers some degree of discretion.
On the flipside, some locations LOVE the publicity that a haunted reputation gives them. Some of these locations specifically offer paranormal investigation teams a chance to investigate for a small price. With many of these pay-to-play locations, public ghost hunts are held in addition to regular daytime activities for the general public---leaving night the ONLY time for these endeavors, but also creating a more creepy and frightening atmosphere which is good for business!
That offers some explanation as to why investigations generally occur at night...but WHY do investigators feel the need to switch off all the lights? This area is a little more gray when it comes to popular theory, but here's just a few reasons why you might want to "go lights out'':
Although it may be a stereotype, but much of the reported paranormal activity we investigate DOES occur at night, when the owners of the location have "gone dark" for themselves. Again, a good interview can be invaluable at finding out when the majority of the activity is said to occur. In these cases, it is important to investigate under the same conditions as the activity is reported. Headlights bouncing off a bedroom window from outdoor traffic doesn't look the same with the lights on...and is often the root cause of many false positives.
If you follow the theory that a ghost can either give off or disrupt EMF readings, then turning off the lights (or better yet, actually cutting power completely) will cut down on false positives. However, it is important to really do a thorough baseline readings check of the entire location BEFORE the lights are cut, as well as AFTER.
It is also theorized that should an entity manifest, it will likely be emitting its own light. A darkened location may make spotting an anomaly easier...and the heightened state of other senses can also help in the observation vigil. Hehehe, and if you're fond of what I call the "flashlight trick"---asking an entity to turn on a flashlight (or even to light up the lights on a K-II or similar device), then darkness is useful to help spot changes, both on camera and in real time.
Lastly, it comes back to a question of obstacles and limitations...some places simply don't have power! I've investigated "abandoned" locations, houses that are in the process of being sold and other locations that simply don't have power hooked up to certain areas, like basements and attics. In those cases, there isn't much of a choice.
No two investigations are alike, just like no two investigators are alike. We all have our own theories and ideas...and we all have our own way of doing things, sometimes heavily influenced by what we see on television. I hope the explanations I've touched upon above have offered some insight, but keep in mind that there are many other reasons as to why (or why not)....Ghost Hunters Do It In The Dark!
