You've followed the usual tips for getting enough sleep. You have a regular sleep schedule, avoid caffeine and daytime naps, and exercise regularly. You also avoid lighted screens before bed and manage stress. Still, it's been weeks since you've had a good night's sleep. Is it time for a nonprescription sleep aid? Here's what you need to know if you're considering medication to help you sleep.

Sleep aids available without a prescription can be effective for an occasional sleepless night. There are a few caveats, however.

Most sleep aids available without a prescription contain antihistamines. Tolerance to the sedative effects of antihistamines can develop quickly. The longer you take them, the less likely they are to make you sleepy.

In addition, some sleep aids available without a prescription can leave you feeling groggy and unwell the next day. This is the so-called hangover effect.

Medication interactions are possible as well, and much remains unknown about the safety and effectiveness of sleep aids available without a prescription.

Sleep aids available without a prescription are widely available. Common choices and the potential side effects include:

• Diphenhydramine (Benadryl). Diphenhydramine is a sedating antihistamine. Side effects might include daytime drowsiness, dry mouth, constipation and urinary retention.
• Doxylamine (Unisom). Doxylamine is also a sedating antihistamine. Side effects are similar to those of diphenhydramine.
• Melatonin. The hormone melatonin helps control your natural sleep-wake cycle. Some research suggests that melatonin supplements might be helpful in treating jet lag or reducing the time it takes to fall asleep — although the effect is typically mild. Side effects can include headaches, nausea and daytime sleepiness.
• Valerian. Supplements made from this plant are sometimes taken as sleep aids. Although a few studies indicate some therapeutic benefit, other studies haven't found the same benefits. Side effects appear to be mild and may include headache and weakness.

Store brands containing the same active ingredients as brand-name sleep aids are commonly available, too. Store brands have the same risks and benefits as their brand-name counterparts, often at a more reasonable cost.

When using nonprescription sleep aids, follow these steps:

• Start with your health care provider. Ask your health care provider if the sleep aid might interact with other medications or underlying conditions. Also ask what dosage to take.
• Keep precautions in mind. Diphenhydramine and doxylamine aren't recommended for people who have certain health problems, including closed-angle glaucoma, peptic ulcer and urinary retention. In addition, sleep aids pose risks for women who are pregnant or breastfeeding, and might pose risks for people over age 65, including an increased risk of dementia.
• Take it one day at a time. Nonprescription sleep aids might be a temporary solution for sleep problems. However, they're not intended for long-term use.
• Avoid alcohol. Never mix alcohol and sleep aids. Alcohol can increase the sedative effects of the medication.
• Beware of side effects. Don't drive or attempt other activities that require alertness while taking sleep aids.

Everyone benefits from a good night's sleep. If you continue to have trouble sleeping, talk to your health care provider. In addition to lifestyle changes, your provider might recommend behavior therapy. This type of therapy may help you learn new sleep habits and ways to make your sleeping environment more conducive to sleep. In some cases, short-term use of prescription sleep aids might be recommended as well.