If you take melatonin, it’s best to take it with no alcohol in your body or a long time after you’ve had any alcoholic drinks. Depending on how much you’ve had to drink, wait 2-3 hours before taking melatonin as a sleep aid.

Melatonin is a hormone that your body naturally makes to help keep your sleep cycle consistent. This cycle is also known as your circadian rhythm. This is also sometimes called the “biological clock.” Melatonin plays a major role in maintaining your sleep cycle. Your body produces most of it in the hours after the sun goes down. Most of it is made especially between 11 p.m. and 3 a.m.

Melatonin is also available as a nutritional supplement. You can buy it at almost any pharmacy or drugstore that sells supplements or medicines. It’s often recommended as a sleep aid or as a quick fix for jet lag or insomnia.

Read more: An end to jet lag? New research on resetting your biological clock »

Even though alcohol is a sedative that can make you feel sleepy after a few drinks, it’s known to reduce the amount of melatonin that your body can create. This can interrupt your sleep cycle. Alcohol can also cause some of the muscles around your airways to work differently and affect your breathing. This can make it hard to sleep if you have a breathing issue, such as sleep apnea.

Because combining alcohol and melatonin can cause negative side effects to your health, it’s not recommended. Some of these side effects can be disruptive or potentially dangerous, such as:

  • drowsiness, which can make it much harder for you to drive or focus on certain tasks
  • dizziness, which can make driving or even walking around dangerous
  • increased anxiety, which can make you feel irritable or raise your blood pressure

Combining melatonin and alcohol can affect your liver’s ability to create certain enzymes. The following complications may also result:

  • flushing in your face and upper body
  • swelling in your feet and ankles
  • an abnormally fast heartbeat
  • trouble focusing or thinking clearly
  • feeling abnormally cold or shivering with no clear cause
  • trouble breathing
  • passing out

See your doctor if you experience any of these side effects.

If you’ve been having insomnia or sleeping inconsistently, talk to your doctor before taking melatonin supplements as a sleep aid. Your doctor may decide that melatonin isn’t the best solution for your sleeping issues. In the case that you have a sleep disorder, other medications or treatments may be more effective in helping you sleep better at night.

Read more: Sleep disorder warning signs »

Supplements come in doses from 1 milligram (mg) to 10 mg. Talk to your doctor about what dose works best for you and your body’s metabolism. Doses used to help you sleep are usually between 0.1 mg and 5 mg. Dosage will change depending on health issues, age, reasons for taking it, and length of time taking it. It is difficult to pinpoint the exact dosage for each person because melatonin is not regulated by the U.S. Food and Drug Administration (FDA). Dosage can also vary by brand. Here are some general guidelines for taking melatonin:

  • Many doctors and nutritionists recommend taking melatonin about 30 minutes before you plan to go to bed.
  • There are different ways to consume melatonin. Tablets are the most widely available type in stores. Melatonin has also been added to some food and beverage products. But tablets are the safest, most effective way to get melatonin into your system.
  • After taking a melatonin supplement, avoid activities that expose you to “blue light.” These activities include watching television or using a mobile device like a smartphone. This type of light can cause your body to produce less melatonin because of the brightness of these screens. It can also make a supplement less effective.
  • If you’re taking a melatonin supplement to help you get to sleep, avoid alcohol after you’ve taken the supplement. Many melatonin supplements are time-release. This means that they take some time to begin working. Many of them begin working about 30 minutes after you’ve taken them. Having an alcoholic drink interrupts this process and can make the supplement not work as well.

Melatonin supplements don’t carry a lot of risks or negative side effects. Most of the time, in controlled doses, melatonin won’t have any noticeable effects on your body or sleep cycle. Buy from a reputable source, because melatonin supplements are not standardized in processing or packaging. Melatonin is not monitored by the FDA for purity, safety, or effectiveness.

Melatonin can have some risks in its interactions with some prescription drugs, including:

  • blood thinners
  • birth control
  • diabetes medications
  • medications for the immune system (immunosuppressants)

Some possible side effects of melatonin supplements include:

  • disruption of your sleep cycle, which may be especially discomforting if you work a night shift or have maintained the same sleep habits for a long time
  • feeling sleepy or groggy during the daytime, sometimes long after you’ve woken up
  • abnormal dizziness or disorientation
  • occasional headaches or migraines
  • unexplained but short episodes of depression or depressive feelings

Read more: 8 natural sleep aids »