Daily cleansing isn't only for those who sweat profusely, wear a lot of makeup, or have acne. Washing your face every day is incredibly important for anti-aging and your overall health.
I was out and about in a fun little shopping/boho/arts district called Abbot Kinney in Venice (California, not Italy) the other day and I overheard a mom trying to convince her teenaged daughter to wash her face everyday. She told her daughter she was going to get acne if she didn't cleanse every day, and then sighed to an innocent saleswoman that her daughter never heeds her advice.
I don't interfere in the parenting strategies of strangers, but I thought the mother's argument would've been more effective if she just told her daughter that she is causing her skin to age faster by not washing, and possibly inviting carcinogens to mutate her DNA due to her lack of skin hygiene. I think that type of fear-mongering is far more effective than just the threat of pimples.
Plus I also know that acne is not caused by one refusing to wash their face, if the solution were that easy the acne-remedy industry wouldn't be a multi-billion dollar industry. Also, I think people with acne would have figured out this trick by now.
Nevertheless, washing your face daily will assist in preventing clogged pores, which is a cause of acne and inflammation in some. Face washing is also necessary for removing excess makeup, and refreshing your skin. However, there is an often overlooked health benefit to proper cleansing: removing environmental pollutants. Regardless if you load your skin with skin care or makeup, pollutants stick to our skin due to the natural oils found on the surface. Pollutants have the potential to be carcinogenic, and therefore need to be washed off by the end of the day.
The importance of face washing is greatest in the evening: to remove the makeup, sweat, and pollutants your face has accumulated throughout the day. Its also a great prep for your nightly skin care regimen. With that said, its only necessary (and healthy) to wash your face in the evening. If you sleep on a clean pillow case at night and do not sweat a great deal during sleep, your skin doesn't need to washed again in the morning.
The reason why I advise against washing your face in the morning is because this can do two things to you (depending on your skin type):
The second one is pretty ironic because acne has this great myth surrounding it that those who have it somehow brought this upon themselves due to some inability to keep their face clean. However, anyone who has had (or knows someone with) acne knows that people with acne wash their face too much.
The problem with washing your face too much when you already have oily, acne prone skin is that you are causing your skin to produce too much sebum (oil) to compensate for the loss of oil from over-cleansing. The problem here is that the sebum your body produces to correct this imbalance/loss of oil has a fatty acid profile too high in oleic acid. Oleic acid can be inflammatory and causes clogged pores. And what does inflammation + clogged pores = ? It equals acne.
So your best bet whether you have oily, dry, normal, or combo skin is to just wash your face at night, and do it with an oil-based, pH balanced cleanser to prevent your skin's natural oils from being stripped off (which can lead to dryness or too much oil depending on your skin type). Just be sure to sleep on a clean pillowcase and in a room cool enough to prevent sweating during sleep.
Also be sure to wash with your hands only. Don't use those face brushes (manual or electronic). Those are physical exfoliants, and you all know how I feel about those.
Oh, and I put so much skin care product on my face at night, I just don't have nice pillowcases anymore. Its a small price to pay for having great skin.