Can you go tanning twice in one day?

Not advisable - risk of skin cancer later very high through daily tanning. Alternatively keep your exposure to the sun limited to the times the sun rays are not so powerful.

Briar Carwell's Edit:

You can, it's not recommended. Melanogenesis is the process in which your body reacts to the sun. During UV exposure, your skin's melanin production increases as your skin's natural defense against sunburn. Melanocytes produce melanin, which after sun exposure, darkens within about 24-48 hours. You want to give your body time to reach its peak melanin production because more melanin means a darker tan. For this reason, if you are tanning, it's recommended you go every other day. If you are trying to get a great tan, gradually build it. Don't be impatient. Stay hydrated and use a great moisturizing lotion without mineral oil, alcohol, or lanolin (which are awful for a tan) because properly hydrated/moisturized skin tans about 60% better. Lastly, avoid burning/over exposure, which can inhibit your tanning process, damage your skin, and put you at risk for skin cancer. I recommend using an spf 8-15 sunblock with non-nano particle zinc oxide while outdoors.

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